Magnetic tape reuse across products

Abstract

A method, in accordance with one aspect, includes writing, by a tape drive, data tracks to a data band of a magnetic tape having servo bands flanking the data band, the writing being performed using a magnetic head that is not designed for a format of the magnetic tape. The writing includes overwriting a portion of each of the servo bands with the data tracks. A method, in accordance with another aspect, includes writing data tracks to a data band using a magnetic head that is not designed for a format of the magnetic tape. An effective pitch of servo readers of the magnetic head used simultaneously during the writing matches a servo reader pitch specification of the format of the magnetic tape. An average effective pitch of write transducers of the magnetic head is greater than a data track pitch specification of the format of the magnetic tape.

Description

MAGNETIC TAPE REUSE ACROSS PRODUCTSBACKGROUND

[0001] The present invention relates to data storage systems, and more particularly, thisinvention relates to enabling media reuse across products by increase the writable area of magnetic tapes and / or using servo band overwrite.

[0002] In magnetic storage systems, magnetic transducers read data from and write data ontomagnetic recording media. Data is written on the magnetic recording media by moving amagnetic recording transducer to a position over the media where the data is to be stored. Themagnetic recording transducer then generates a magnetic field, which encodes the data into themagnetic media. Data is read from the media by similarly positioning the magnetic readtransducer and then sensing the magnetic field of the magnetic media. Read and write operationsmay be independently synchronized with the movement of the media to ensure that the data can be read from and written to the desired location on the media.

[0003] An important and continuing goal in the data storage industry is that of increasingthe density of data stored on a medium. For tape storage systems, that goal has led toincreasing the track and linear bit density on recording tape, and decreasing the thickness ofthe magnetic tape medium. However, the development of small footprint, higher performancetape drive systems has created various challenges ranging from the design of tape headassemblies for use in such systems to dealing with tape dimensional instability.

[0004] Storing data on recording tape media is a low-cost approach to storing large scaledata. However, the cost of developing the media for a given format is expensive. Increasing the number of products which can use the same media format lowers the overall cost of the media.

[0005] What is needed is a way to extend the use of magnetic tapes, having servo bandsspecific to a given media format, across products using different read / write head designs,especially those that are not compliant with the particular media format. SUMMARY

[0006] A method, in accordance with one aspect of the present invention, includeswriting, by a tape drive, data tracks to a data band of a magnetic tape having servo bands flanking the data band, the writing being performed using a magnetic head that is not designed for a format of the magnetic tape. The writing includes overwriting a portion of each of the servo bands with the data tracks.

[0007] An apparatus, in accordance with one approach, includes a drive mechanism forpassing a magnetic tape over a magnetic head, and a controller electrically coupled to the magnetic head. The controller is configured to cause the magnetic head to write data tracks to a data band of the magnetic tape, the magnetic tape having servo bands flanking the data band. The magnetic head is not designed for a format of the magnetic tape. The writing includes overwriting a portion of each of the servo bands with the data tracks.

[0008] A method, in accordance with one aspect of the present invention, includeswriting, by a tape drive, data tracks to a data band of a magnetic tape having servo bands flanking the data band, the writing being performed using a magnetic head that is not designed for a format of the magnetic tape. An effective pitch of servo readers of themagnetic head used simultaneously during the writing matches a servo reader pitchspecification of the format of the magnetic tape. An average effective pitch of write transducers of the magnetic head is greater than a data track pitch specification of the format of the magnetic tape. The writing includes overwriting a portion of each of the servo bands with the data tracks.

[0009] A computer program product for enabling use of a magnetic tape by a tape drivenot designed for a format of the magnetic tape, in accordance with one aspect of the present invention, includes a computer readable storage medium having program instructions embodied therewith. The program instructions are executable by the tape drive to cause the tape drive to perform any of the foregoing methodology. The advantages and technical effects of the computer program product are similar to those set forth above for said methodology.

[0010] Any of these approaches may be implemented in a magnetic data storage systemsuch as a tape drive system, which may include a magnetic head, a drive mechanism for passing a magnetic medium (e.g., recording tape) over the magnetic head, and a controller electrically coupled to the magnetic head.

[0011] Other aspects of the present invention will become apparent from the followingdetailed description, which, when taken in conjunction with the drawings, illustrate by way of example the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a diagram of a computing environment, in accordance with one aspectof the present invention.

[0013] FIG. 2A is a schematic diagram of a simplified tape drive system, in accordance withone aspect.

[0014] FIG. 2B is a schematic diagram of a tape cartridge, in accordance with one aspect.

[0015] FIG. 2C illustrates a side view of a flat-lapped, bi-directional, two-module magnetictape head, in accordance with one aspect.

[0016] FIG. 2D is a tape bearing surface view taken from Line 2D of FIG. 2C.

[0017] FIG. 2E is a detailed view taken from Circle 2E of FIG. 2D.

[0018] FIG. 2F is a detailed view of a partial tape bearing surface of a pair of modules.

[0019] FIG. 3 is a partial tape bearing surface view of a magnetic head having a write-read-write configuration, in accordance with one aspect.

[0020] FIG. 4 is a partial tape bearing surface view of a magnetic head having a read-write-read configuration, in accordance with one aspect.

[0021] FIG. 5 is a side view of a magnetic tape head with three modules where themodules all generally lie along about parallel planes, in accordance with one aspect.

[0022] FIG. 6 is a side view of a magnetic tape head with three modules in a tangent(angled) configuration, in accordance with one aspect.

[0023] FIG. 7 is a side view of a magnetic tape head with three modules in an overwrapconfiguration.

[0024] FIGS. 8A-8C are schematics depicting the principles of tape tenting.

[0025] FIG. 9 is a representational diagram of files and indexes stored on a magnetic tape, inaccordance with one aspect.

[0026] FIG. 10 is a partial representative view of a magnetic tape formatted according to theLTO 10 format.

[0027] FIG. 11 is a flowchart of a method, in accordance with one approach.

[0028] FIG. 12 is a partial representative view of a magnetic tape having two prewrittenservo bands, in accordance with one approach.

[0029] FIG. 13 is a partial representative view of a magnetic tape having two prewrittenservo bands, in accordance with one approach.

[0030] FIG. 14 is a partial representative view of a magnetic tape having two prewrittenservo bands, in accordance with one approach.

[0031] FIG. 15 is a flowchart of a method, in accordance with one approach.

[0032] FIG. 16 is a representation of a servo and data band layout on a magnetic tape asspecified by a predefined format.

[0033] FIG. 17 illustrates the magnetic tape of FIG. 16 in which two of the servo bandsare overwritten, in accordance with one approach.

[0034] FIG. 18 depicts a representation of a magnetic head that wrote the data bands ofFIG.17.

[0035] FIG. 19 is representational view of regions on a magnetic tape according to aconventional format.

[0036] FIG. 20, part (a) is a representational view of magnetic tape media in raw format asprovided by a supplier; part (b) is a representation of a servo band in raw format as provided by a supplier; part (c) is a representation view of the magnetic tape media of part (a) written by amagnetic head with wider element spacing according to a different format; part (d) is arepresentation of a partially overwritten servo band of part (b) by the magnetic head associated with the format of part (c), in accordance with an exemplary approach.

[0037] FIG. 21 is a representational view of data band and sub-data band composition, inaccordance with an exemplary approach.

[0038] FIG. 22 is a schematic of the servo bands and a single sub data band, in accordancewith an exemplary approach.

[0039] FIG. 23 is a schematic of the servo bands and a two sub data bands for one servoreader per servo band for the case where ^^ = 3 and ^^^ = 2, in accordance with an exemplaryapproach.

[0040] FIG. 24 is a schematic for a 1-band head with ^^ transducers utilizing a dual servoreader option for a 3-module head alignment with a Left (LW) and Right (RW) Writer and CenterRead transducer (CR). S and T servo readers are for forward and reverse writing and readingrespectively and U unused servo readers, in accordance with an exemplary approach.

[0041] FIG. 25 is a schematic for a 2-band head with 2^^ transducers in each Group (A andB) utilizing a dual servo reader option for a 3-module head alignment with a LW and RW andCR. S and T servo readers are for forward and reverse writing and reading respectively and Uunused servo readers, in accordance with an exemplary approach.

[0042] Fig. 26 is a schematic for a 1-band head with ^^ transducers utilizing a dual servoreader option for a 3-module head alignment with a LW, RW and CR, in accordance with an exemplary approach.

[0043] FIG. 27 is a schematic of a tilted head concept for tape dimensional stability (TDS)compensation, in accordance with an exemplary approach.DETAILED DESCRIPTION

[0044] The following description is made for the purpose of illustrating the generalprinciples of the present invention and is not meant to limit the inventive concepts claimedherein. Further, particular features described herein can be used in combination with otherdescribed features in each of the various possible combinations and permutations.

[0045] Unless otherwise specifically defined herein, all terms are to be given theirbroadest possible interpretation including meanings implied from the specification as well asmeanings understood by those skilled in the art and / or as defined in dictionaries, treatises, etc.

[0046] It must also be noted that, as used in the specification and the appended claims,the singular forms "a," "an" and "the" include plural referents unless otherwise specified.

[0047] The following description discloses several preferred aspects of magnetic storagesystems, as well as operation and / or component parts thereof. Various approaches enable theuse of a given media format across products using different read / write head designs. In preferred approaches, media reuse is enabled in part by overwriting a portion of the servopattern for products that are not designed for the particular format of the media.

[0048] A method, in accordance with one aspect of the present invention, includeswriting, by a tape drive, data tracks to a data band of a magnetic tape having servo bands flanking the data band, the writing being performed using a magnetic head that is not designed for a format of the magnetic tape. The writing includes overwriting a portion of eachof the servo bands with the data tracks. This method allows more data to be stored on a tapethan the specification would otherwise allow. Moreover, the present method allows use of a tape having a given media format by a drive having a head that is not configured to operate with that format, thereby allowing reuse of tape media with products not designed for use with said format.

[0049] In one approach, the magnetic head has at least two servo readers positioned onone side of an array of magnetic write transducers and at least two servo readers positioned on an opposite side of the array of magnetic write transducers. The tape drive is configured to use a first one of the servo readers positioned on each side of the array for writing data tracks in a first portion of the data band and to use a second one of the servo readers positioned on each side of the array for writing data tracks in a second portion of the data band. This aspect enables use of one set of servo readers for one portion of the data operations on a given data band and another set of servo readers for another portion of the data operations on the same data band. Because the servo band is overwritten, this feature allows proper positioning using a thinner servo band.

[0050] In one approach, centerlines of the portions of the servo bands used during thewriting are original centerlines of the servo bands. This feature has the technical effect ofretaining the original centerlines of the servo bands.

[0051] In one approach, an effective pitch of servo readers of the magnetic head usedsimultaneously during the writing matches a servo reader pitch specification of the format ofthe magnetic tape. An average effective pitch of write transducers of the magnetic head is greater than a data track pitch specification of the format of the magnetic tape. The greater effective pitch of the write transducers allows more data tracks to be written to a given area ofthe magnetic tape, e.g., in a data band. This generally corresponds to the ability to store moredata on the tape.

[0052] In one approach, centerlines of the portions of the servo bands used during thewriting are offset from original centerlines of the servo bands. This may allow inclusion ofeven more data bands, and thus more data storage, by shifting the new center lines away from their original position.

[0053] In one approach, an effective pitch of servo readers of the magnetic head usedsimultaneously during the writing is less than a servo reader pitch specification of the formatof the magnetic tape. An average effective pitch of write transducers of the magnetic head isgreater than a data track pitch specification of the format of the magnetic tape. The greater effective pitch of the write transducers allows more data tracks to be written to a given area of the magnetic tape. This generally corresponds to the storage of more data on the tape.

[0054] In one approach, one of the servo bands is completely overwritten with datatracks during the writing. This aspect greatly increases the number of data tracks that may bewritten by using the space that was once occupied by the overwritten servo band or bands.

[0055] In the foregoing approach, an effective pitch of servo readers of the magnetichead used simultaneously during the writing may be greater than a width of two of the databands on the magnetic tape. This enables overwrite of an intermediary servo band positioned between the servo bands being used.

[0056] In another aspect of the foregoing approach, the magnetic head has at least twoservo readers positioned on one side of an array of magnetic write transducers and at least two servo readers positioned on an opposite side of the array of magnetic write transducers,and the tape drive is configured to use a first one of the servo readers positioned on each sideof the array for writing a first set of the data tracks and to use a second one of the servoreaders positioned on each side of the array for writing a second set of data tracks. This aspectenables use of one set of servo readers for one portion of the data operations and another setof servo readers for another portion of the data operations, and so on, thereby enabling indexing of the write transducer array all the way across both former data bands.

[0057] An apparatus, such as a tape drive, in accordance with one approach, includes adrive mechanism for passing a magnetic tape over a magnetic head, and a controllerelectrically coupled to the magnetic head. The controller is configured to cause the magnetichead to write data tracks to a data band of the magnetic tape, the magnetic tape having servo bands flanking the data band. The magnetic head is not designed for a format of the magnetic tape. The writing includes overwriting a portion of each of the servo bands with the datatracks. This configuration allows more data to be stored on a tape than the specificationwould otherwise allow. Moreover, the present configuration allows use of a tape having a given media format by a drive having a head that is not configured to operate with that format, thereby allowing reuse of tape media with products not designed for use with said format.

[0058] The magnetic head of such apparatus may have at least two servo readerspositioned on one side of an array of magnetic write transducers and at least two servo readers positioned on an opposite side of the array of magnetic write transducers. Theapparatus may be configured to use a first one of the servo readers positioned on each side ofthe array for writing data tracks in a first portion of the data band and to use a second one of the servo readers positioned on each side of the array for writing data tracks in a secondportion of the data band. This aspect enables use of one set of servo readers for one portion ofthe data operations on a given data band and another set of servo readers for another portion of the data operations on the same data band. Because the servo band is overwritten, this feature allows proper positioning using a thinner servo band.

[0059] In one approach, centerlines of the portions of the servo bands used during thewriting are original centerlines of the servo bands. This feature has the technical effect of retaining the original centerlines of the servo bands.

[0060] In one approach, an effective pitch of servo readers of the magnetic head usedsimultaneously during the writing matches a servo reader pitch specification of the format ofthe magnetic tape. An average effective pitch of write transducers of the magnetic head is greater than a data track pitch specification of the format of the magnetic tape. The greater effective pitch of the write transducers allows more data tracks to be written to a given area ofthe magnetic tape. This generally corresponds to the ability to store more data on the tape.

[0061] In one approach, centerlines of the portions of the servo bands used during thewriting are offset from original centerlines of the servo bands. This may allow inclusion ofeven more data bands, and thus more data storage, by shifting the new center lines away from their original position.

[0062] In one approach, an effective pitch of servo readers of the magnetic head usedsimultaneously during the writing is less than a servo reader pitch specification of the format of the magnetic tape. An average effective pitch of write transducers of the magnetic head is greater than a data track pitch specification of the format of the magnetic tape. The greater effective pitch of the write transducers allows more data tracks to be written to a given area of the magnetic tape. This generally corresponds to the storage of more data on the tape.

[0063] In one approach, one of the servo bands is completely overwritten with datatracks during the writing. This aspect greatly increases the number of data tracks that may be written by using the space that was once occupied by the overwritten servo band or bands.

[0064] In the foregoing approach, an effective pitch of servo readers of the magnetichead used simultaneously during the writing may be greater than a width of two of the data bands on the magnetic tape. This enables overwrite of an intermediary servo band positioned between the servo bands being used.

[0065] In another aspect of the foregoing approach, the magnetic head has at least twoservo readers positioned on one side of an array of magnetic write transducers and at least two servo readers positioned on an opposite side of the array of magnetic write transducers,and the apparatus is configured to use a first one of the servo readers positioned on each sideof the array for writing a first set of the data tracks and to use a second one of the servoreaders positioned on each side of the array for writing a second set of data tracks. This aspectenables use of one set of servo readers for one portion of the data operations and another set of servo readers for another portion of the data operations, and so on, thereby enablingindexing of the write transducer array all the way across both former data bands.

[0066] A method, in accordance with one aspect of the present invention, includeswriting, by a tape drive, data tracks to a data band of a magnetic tape having servo bands flanking the data band, the writing being performed using a magnetic head that is notdesigned for a format of the magnetic tape. An effective pitch of servo readers of themagnetic head used simultaneously during the writing matches a servo reader pitch specification of the format of the magnetic tape. An average effective pitch of write transducers of the magnetic head is greater than a data track pitch specification of the format of the magnetic tape. The writing includes overwriting a portion of each of the servo bandswith the data tracks. This method allows more data to be stored on a tape than thespecification would otherwise allow. Moreover, the present method allows use of a tapehaving a given media format by a drive having a head that is not configured to operate with that format, thereby allowing reuse of tape media with products not designed for use with said format. The greater effective pitch of the write transducers allows more data tracks to be written to a given area of the magnetic tape, e.g., in a data band. This generally corresponds to the ability to store more data on the tape.

[0067] In one approach, the magnetic head has at least two of the servo readerspositioned on one side of an array of magnetic write transducers and at least two of the servo readers positioned on an opposite side of the array of magnetic write transducers. The tape drive is configured to use a first one of the servo readers positioned on each side of the array for writing data tracks in a first portion of the data band and to use a second one of the servo readers positioned on each side of the array for writing data tracks in a second portion of the data band. This aspect enables use of one set of servo readers for one portion of the data operations on a given data band and another set of servo readers for another portion of the data operations on the same data band. Because the servo band is overwritten, this feature allows proper positioning using a thinner servo band.

[0068] A computer program product for enabling use of a magnetic tape by a tape drivenot designed for a format of the magnetic tape, in accordance with one aspect of the present invention, includes a computer readable storage medium having program instructions embodied therewith. The program instructions are executable by the tape drive to cause the tape drive to perform any combination of steps from the foregoing methodology. The advantages and technical effects of the computer program product are similar to those set forth above for said methodology.

[0069] Various aspects of the present disclosure are described by narrative text,flowcharts, block diagrams of computer systems and / or block diagrams of the machine logic included in computer program product (CPP) embodiments. With respect to any flowcharts, depending upon the technology involved, the operations can be performed in a different order than what is shown in a given flowchart. For example, again depending upon the technology involved, two operations shown in successive flowchart blocks may be performed in reverse order, as a single integrated step, concurrently, or in a manner at least partially overlapping in time.

[0070] A computer program product embodiment ("CPP embodiment" or “CPP”) is aterm used in the present disclosure to describe any set of one, or more, storage media (also called "mediums") collectively included in a set of one, or more, storage devices that collectively include machine readable code corresponding to instructions and / or data forperforming computer operations specified in a given CPP claim. A "storage device" is any tangible device that can retain and store instructions for use by a computer processor. Without limitation, the computer readable storage medium may be an electronic storage medium, a magnetic storage medium, an optical storage medium, an electromagnetic storage medium, a semiconductor storage medium, a mechanical storage medium, or any suitable combination of the foregoing. Some known types of storage devices that include these mediums include: diskette, hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or Flash memory), static random access memory (SRAM), compact disc read-only memory (CD-ROM), digital versatile disk (DVD), memory stick, floppy disk, mechanically encoded device (such as punch cards or pits / lands formed in a major surface of a disc) or any suitable combination of the foregoing. A computer readable storage medium, as that term is used in the present disclosure, is not to be construed as storage in the form of transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide, light pulses passing through a fiber optic cable, electrical signals communicated through a wire, and / or other transmission media. As will be understood by those of skill in the art, data is typically moved at some occasional points in time during normal operations of a storage device, such as during access, de-fragmentation or garbage collection, but this does not render the storage device as transitory because the data is not transitory while it is stored.

[0071] Computing environment 100 contains an example of an environment for theexecution of at least some of the computer code involved in performing the inventive methods, such as code in block 200 for operating on media for which a tape drive of the computing environment 100 was not designed. In addition to block 200, computing environment 100 includes, for example, computer 101, wide area network (WAN) 102, end user device (EUD) 103, remote server 104, public cloud 105, and private cloud 106. In this embodiment, computer 101 includes processor set 110 (including processing circuitry 120 and cache 121), communication fabric 111, volatile memory 112, persistent storage 113 (including operating system 122 and block 200, as identified above), peripheral device set 114 (including user interface (UI) device set 123, storage 124, and Internet of Things (IoT) sensor set 125), and network module 115. Remote server 104 includes remote database 130. Public cloud 105 includes gateway 140, cloud orchestration module 141, host physical machine set 142, virtual machine set 143, and container set 144.

[0072] COMPUTER 101 may take the form of a desktop computer, laptop computer,tablet computer, smart phone, smart watch or other wearable computer, mainframe computer,quantum computer or any other form of computer or mobile device now known or to be developed in the future that is capable of running a program, accessing a network or querying a database, such as remote database 130. As is well understood in the art of computer technology, and depending upon the technology, performance of a computer-implemented method may be distributed among multiple computers and / or between multiple locations. On the other hand, in this presentation of computing environment 100, detailed discussion is focused on a single computer, specifically computer 101, to keep the presentation as simple as possible. Computer 101 may be located in a cloud, even though it is not shown in a cloud in Figure 1. On the other hand, computer 101 is not required to be in a cloud except to any extent as may be affirmatively indicated.

[0073] PROCESSOR SET 110 includes one, or more, computer processors of any typenow known or to be developed in the future. Processing circuitry 120 may be distributed over multiple packages, for example, multiple, coordinated integrated circuit chips. Processing circuitry 120 may implement multiple processor threads and / or multiple processor cores. Cache 121 is memory that is located in the processor chip package(s) and is typically used fordata or code that should be available for rapid access by the threads or cores running onprocessor set 110. Cache memories are typically organized into multiple levels depending upon relative proximity to the processing circuitry. Alternatively, some, or all, of the cache for the processor set may be located “off chip.” In some computing environments, processor set 110 may be designed for working with qubits and performing quantum computing.

[0074] Computer readable program instructions are typically loaded onto computer 101to cause a series of operational steps to be performed by processor set 110 of computer 101 and thereby effect a computer-implemented method, such that the instructions thus executed will instantiate the methods specified in flowcharts and / or narrative descriptions of computer- implemented methods included in this document (collectively referred to as “the inventive methods”). These computer readable program instructions are stored in various types of computer readable storage media, such as cache 121 and the other storage media discussed below. The program instructions, and associated data, are accessed by processor set 110 to control and direct performance of the inventive methods. In computing environment 100, at least some of the instructions for performing the inventive methods may be stored in block 200 in persistent storage 113.

[0075] COMMUNICATION FABRIC 111 is the signal conduction path that allows thevarious components of computer 101 to communicate with each other. Typically, this fabric is made of switches and electrically conductive paths, such as the switches and electricallyconductive paths that make up buses, bridges, physical input / output ports and the like. Other types of signal communication paths may be used, such as fiber optic communication paths and / or wireless communication paths.

[0076] VOLATILE MEMORY 112 is any type of volatile memory now known or to bedeveloped in the future. Examples include dynamic type random access memory (RAM) or static type RAM. Typically, volatile memory 112 is characterized by random access, but this is not required unless affirmatively indicated. In computer 101, the volatile memory 112 is located in a single package and is internal to computer 101, but, alternatively or additionally, the volatile memory may be distributed over multiple packages and / or located externally with respect to computer 101.

[0077] PERSISTENT STORAGE 113 is any form of non-volatile storage for computersthat is now known or to be developed in the future. The non-volatility of this storage means that the stored data is maintained regardless of whether power is being supplied to computer 101 and / or directly to persistent storage 113. Persistent storage 113 may be a read only memory (ROM), but typically at least a portion of the persistent storage allows writing of data, deletion of data and re-writing of data. Some familiar forms of persistent storage include magnetic disks and solid state storage devices. Operating system 122 may take several forms, such as various known proprietary operating systems or open source Portable Operating System Interface-type operating systems that employ a kernel. The code included in block 200 typically includes at least some of the computer code involved in performing the inventive methods.

[0078] PERIPHERAL DEVICE SET 114 includes the set of peripheral devices ofcomputer 101. Data communication connections between the peripheral devices and the other components of computer 101 may be implemented in various ways, such as Bluetooth connections, Near-Field Communication (NFC) connections, connections made by cables (such as universal serial bus (USB) type cables), insertion-type connections (for example, secure digital (SD) card), connections made through local area communication networks and even connections made through wide area networks such as the internet. In various embodiments, UI device set 123 may include components such as a display screen, speaker, microphone, wearable devices (such as goggles and smart watches), keyboard, mouse,printer, touchpad, game controllers, and haptic devices. Storage 124 is external storage, suchas an external hard drive, or insertable storage, such as an SD card. Storage 124 may be persistent and / or volatile. In some embodiments, storage 124 may take the form of a quantum computing storage device for storing data in the form of qubits. In embodiments wherecomputer 101 is required to have a large amount of storage (for example, where computer 101 locally stores and manages a large database) then this storage may be provided by peripheral storage devices designed for storing very large amounts of data, such as a storage area network (SAN) that is shared by multiple, geographically distributed computers. IoT sensor set 125 is made up of sensors that can be used in Internet of Things applications. Forexample, one sensor may be a thermometer and another sensor may be a motion detector.

[0079] NETWORK MODULE 115 is the collection of computer software, hardware,and firmware that allows computer 101 to communicate with other computers through WAN 102. Network module 115 may include hardware, such as modems or Wi-Fi signal transceivers, software for packetizing and / or de-packetizing data for communication network transmission, and / or web browser software for communicating data over the internet. In some embodiments, network control functions and network forwarding functions of network module 115 are performed on the same physical hardware device. In other embodiments (for example, embodiments that utilize software-defined networking (SDN)), the control functions and the forwarding functions of network module 115 are performed on physically separate devices, such that the control functions manage several different network hardware devices. Computer readable program instructions for performing the inventive methods can typically be downloaded to computer 101 from an external computer or external storage device through a network adapter card or network interface included in network module 115.

[0080] WAN 102 is any wide area network (for example, the internet) capable ofcommunicating computer data over non-local distances by any technology for communicating computer data, now known or to be developed in the future. In some embodiments, the WAN 102 may be replaced and / or supplemented by local area networks (LANs) designed to communicate data between devices located in a local area, such as a Wi-Fi network. The WAN and / or LANs typically include computer hardware such as copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and edge servers.

[0081] END USER DEVICE (EUD) 103 is any computer system that is used andcontrolled by an end user (for example, a customer of an enterprise that operates computer 101), and may take any of the forms discussed above in connection with computer 101. EUD 103 typically receives helpful and useful data from the operations of computer 101. For example, in a hypothetical case where computer 101 is designed to provide a recommendation to an end user, this recommendation would typically be communicated from network module 115 of computer 101 through WAN 102 to EUD 103. In this way, EUD 103can display, or otherwise present, the recommendation to an end user. In some embodiments, EUD 103 may be a client device, such as thin client, heavy client, mainframe computer, desktop computer and so on.

[0082] REMOTE SERVER 104 is any computer system that serves at least some dataand / or functionality to computer 101. Remote server 104 may be controlled and used by the same entity that operates computer 101. Remote server 104 represents the machine(s) that collect and store helpful and useful data for use by other computers, such as computer 101. For example, in a hypothetical case where computer 101 is designed and programmed to provide a recommendation based on historical data, then this historical data may be provided to computer 101 from remote database 130 of remote server 104.

[0083] PUBLIC CLOUD 105 is any computer system available for use by multipleentities that provides on-demand availability of computer system resources and / or other computer capabilities, especially data storage (cloud storage) and computing power, withoutdirect active management by the user. Cloud computing typically leverages sharing ofresources to achieve coherence and economies of scale. The direct and active management of the computing resources of public cloud 105 is performed by the computer hardware and / or software of cloud orchestration module 141. The computing resources provided by public cloud 105 are typically implemented by virtual computing environments that run on variouscomputers making up the computers of host physical machine set 142, which is the universeof physical computers in and / or available to public cloud 105. The virtual computing environments (VCEs) typically take the form of virtual machines from virtual machine set 143 and / or containers from container set 144. It is understood that these VCEs may be stored as images and may be transferred among and between the various physical machine hosts, either as images or after instantiation of the VCE. Cloud orchestration module 141 managesthe transfer and storage of images, deploys new instantiations of VCEs and manages activeinstantiations of VCE deployments. Gateway 140 is the collection of computer software, hardware, and firmware that allows public cloud 105 to communicate through WAN 102.

[0084] Some further explanation of virtualized computing environments (VCEs) willnow be provided. VCEs can be stored as “images.” A new active instance of the VCE can be instantiated from the image. Two familiar types of VCEs are virtual machines and containers. A container is a VCE that uses operating-system-level virtualization. This refers to an operating system feature in which the kernel allows the existence of multiple isolated user- space instances, called containers. These isolated user-space instances typically behave as real computers from the point of view of programs running in them. A computer program runningon an ordinary operating system can utilize all resources of that computer, such as connected devices, files and folders, network shares, CPU power, and quantifiable hardware capabilities. However, programs running inside a container can only use the contents of the container and devices assigned to the container, a feature which is known as containerization.

[0085] PRIVATE CLOUD 106 is similar to public cloud 105, except that the computingresources are only available for use by a single enterprise. While private cloud 106 is depicted as being in communication with WAN 102, in other embodiments a private cloud may be disconnected from the internet entirely and only accessible through a local / private network. A hybrid cloud is a composition of multiple clouds of different types (for example,private, community or public cloud types), often respectively implemented by differentvendors. Each of the multiple clouds remains a separate and discrete entity, but the larger hybrid cloud architecture is bound together by standardized or proprietary technology that enables orchestration, management, and / or data / application portability between the multiple constituent clouds. In this embodiment, public cloud 105 and private cloud 106 are both part of a larger hybrid cloud.

[0086] In some aspects, a system according to various approaches may include aprocessor and logic integrated with and / or executable by the processor, the logic being configured to perform one or more of the process steps recited herein. The processor may be of any configuration as described herein, such as a discrete processor or a processing circuit that includes many components such as processing hardware, memory, I / O interfaces, etc. By integrated with, what is meant is that the processor has logic embedded therewith as hardware logic, such as an application specific integrated circuit (ASIC), a FPGA, etc. By executable by the processor, what is meant is that the logic is hardware logic; software logic such as firmware, part of an operating system, part of an application program; etc., or somecombination of hardware and software logic that is accessible by the processor andconfigured to cause the processor to perform some functionality upon execution by the processor. Software logic may be stored on local and / or remote memory of any memory type,as known in the art. Any processor known in the art may be used, such as a softwareprocessor module and / or a hardware processor such as an ASIC, a FPGA, a central processing unit (CPU), an integrated circuit (IC), a graphics processing unit (GPU), etc.

[0087] FIG. 2A illustrates a simplified tape drive 201 of a tape-based data storagesystem, which may be employed in the context of the present invention. While one specificimplementation of a tape drive is shown in FIG.2A, it should be noted that the embodiments described herein may be implemented in the context of any type of tape drive system.

[0088] As shown, a tape supply cartridge 203 and a take-up reel 205 are provided tosupport a tape 207. One or more of the reels may form part of a removable cartridge and arenot necessarily part of the tape drive 201. The tape drive, such as that illustrated in FIG. 2A,may further include drive motor(s) to drive the tape supply cartridge 203 and the take-up reel205 to move the tape 207 over a tape head 211 of any type. Such head may include an arrayof read transducers (also referred to as readers), write transducers (also known in the art aswriters), or both.

[0089] Guides 213 guide the tape 207 across the tape head 211. Such tape head 211 is inturn coupled to a controller 215 via a cable 217. The controller 215, may be or include aprocessor and / or any logic for controlling any subsystem of the drive 201. For example, thecontroller 215 typically controls head functions such as servo following, data writing, datareading, etc. The controller 215 may include at least one servo channel and at least one datachannel, each of which include data flow processing logic configured to process and / or storeinformation to be written to and / or read from the tape 207. The controller 215 may operateunder logic known in the art, as well as any logic disclosed herein, and thus may be considered as a processor for any of the descriptions of tape drives included herein, in variousapproaches. The controller 215 may be coupled to a memory 219 of any known type, whichmay store instructions executable by the controller 215. Moreover, the controller 215 may beconfigured and / or programmable to perform or control some or all of the methodologiespresented herein. Thus, the controller 215 may be considered to be configured to performvarious operations by way of logic programmed into one or more chips, modules, and / orblocks; software, firmware, and / or other instructions being available to one or moreprocessors; etc., and combinations thereof.

[0090] The cable 217 may include read / write circuits to transmit data to the tape head211 to be recorded on the tape 207 and to receive data read by the tape head 211 from thetape 207. An actuator 221 controls position of the tape head 211 relative to the tape 207.

[0091] An interface 223 may also be provided for communication between the tape drive201 and a host (internal or external) to send and receive the data and for controlling theoperation of the tape drive 201 and communicating the status of the tape drive 201 to the host,all as will be understood by those of skill in the art.

[0092] FIG. 2B illustrates an exemplary tape cartridge 231, according to one aspect ofthe present invention. Such tape cartridge 231 may be used with a system such as that shownin FIG. 2A. As shown, the tape cartridge 231 includes a housing 233, a tape 207 in thehousing 233, and a nonvolatile memory 237 coupled to the housing 233. In some approaches,the nonvolatile memory 237 may be embedded inside the housing 233, as shown in FIG. 2B.In more approaches, the nonvolatile memory 237 may be attached to the inside or outside ofthe housing 233 without modification of the housing 233. For example, the nonvolatilememory may be embedded in a self-adhesive label 235. In one preferred approach, thenonvolatile memory 237 may be a Flash memory device, read-only memory (ROM) device,etc., embedded into or coupled to the inside or outside of the tape cartridge 231. The nonvolatile memory is accessible by the tape drive and the tape operating software (the driversoftware), and / or another device.

[0093] By way of example, FIG. 2C illustrates a side view of a flat-lapped, bi-directional, two-module magnetic tape head 211 which may be implemented in the context ofthe present invention. As shown, the head includes a pair of bases 202, each equipped with amodule 204, and fixed at a small angle α with respect to each other. The bases may be “U-beams” that are adhesively coupled together. Each module 204 includes a substrate 204A anda closure 204B with a thin film portion, commonly referred to as a “gap” in which the readtransducers and / or write transducers 206 are formed. In use, a tape 208 is moved over themodules 204 along a media (tape) bearing surface 209 in the manner shown for reading andwriting data on the tape 208 using the read transducers and write transducers. The wrap angleθ of the tape 208 at edges going onto and exiting the flat media support surfaces 209 areusually between about 0.1 degree and about 3 degrees.

[0094] The substrates 204A are typically constructed of a wear resistant material, such asa ceramic. The closures 204B may be made of the same or similar ceramic as the substrates 204A.

[0095] Cables 217 are provided for enabling communication between the controller andthe transducers 206 of each of the modules 204. Pads on a cable 217 are typically wirebonded to pads on the associated module 204.

[0096] The read transducers and write transducers may be arranged in a piggyback ormerged configuration. An illustrative piggybacked configuration comprises a (magnetically inductive) write transducer on top of (or below) a (magnetically shielded) read transducer(e.g., a magnetoresistive reader, etc.), wherein the poles of the write transducer and theshields of the read transducer are generally separated. An illustrative merged configuration comprises one reader shield in the same physical layer as one writer pole (hence, "merged").The read transducers and write transducers may also be arranged in an interleavedconfiguration. Alternatively, each array of channels may be read transducers or writetransducers only. Any of these arrays may contain one or more servo readers for reading servo data on the medium.

[0097] FIG. 2D illustrates the tape bearing surface 209 of one of the modules 204 takenfrom Line 2D of FIG. 2C. A representative tape 208 is shown in dashed lines. The module204 is preferably long enough to be able to support the tape as the head steps between data bands.

[0098] In this example, the tape 208 includes 4 to 32 data bands, e.g., with 16 data bandsand 17 servo tracks 210, as shown in FIG. 2D on a one-half inch wide tape 208. The databands are defined between servo tracks 210. Each data band may include a number of datatracks, for example 1024 data tracks (not shown). During read / write operations, the readtransducers and / or write transducers 206 are positioned to specific track positions within oneof the data bands. Outer readers, sometimes called servo readers, read the servo tracks 210. The servo signals are in turn used in a conventional manner to keep the read transducers and / or write transducers 206 aligned with a particular set of tracks during the read / write operations.

[0099] FIG. 2E depicts a plurality of read transducers and / or write transducers 206formed in a gap 218 on the module 204 in Circle 2E of FIG. 2D. As shown in FIG. 2E, thearray of read transducers and write transducers 206 includes, for example, 16 writetransducers 214, 16 read transducers 216 and two servo readers 212, though the number ofelements may vary. Illustrative approaches include 8, 16, 32, 40, and 64 active readtransducers and / or write transducers 206 per array, and alternatively interleaved designshaving odd numbers of read transducers or write transducers such as 17, 25, 33, etc. Anillustrative approach includes 32 read transducers per array and / or 32 write transducers perarray, where the actual number of transducer elements could be greater, e.g., 33, 34, etc.Multiple simultaneously-operated transducers allow the tape to travel at a modest velocity while maintaining a high data transfer rate. Lower velocities are desirable to reduce mechanical difficulties from speed-induced tracking.

[0100] While the read transducers and write transducers may be arranged in a piggybackconfiguration as shown in FIG. 2E, the read transducers 216 and write transducers 214 mayalso be arranged in an interleaved configuration. Alternatively, each array of read transducersand / or write transducers 206 may be read transducers or write transducers only, and the arraysmay contain one or more servo readers 212. As noted by considering FIGS. 2C and 2D-2Etogether, each module 204 may include a complementary set of read transducers and / or writetransducers 206 for such things as bi-directional reading and writing, read-while-write capability, backward compatibility, etc.

[0101] FIG. 2F shows a partial tape bearing surface view of complementary modules ofa magnetic tape head 211, according to one approach. In this approach, each module has aplurality of read / write (R / W) pairs in a piggyback configuration formed on a commonsubstrate 204A and an optional electrically insulative insulating layer 236. The writetransducers 214 and the read transducers 216 are aligned parallel to an intended direction oftravel of a tape medium thereacross to form an R / W pair, exemplified by R / W pairs 222. Notethat the intended direction of tape travel is sometimes referred to herein as the direction of tape travel, and such terms may be used interchangeably. Such direction of tape travel may be inferred from the design of the system, e.g., by examining the guides; observing the actual direction of tape travel relative to the reference point; etc. Moreover, in a system operable forbi-direction reading and / or writing, the direction of tape travel in both directions is typicallyparallel and thus both directions may be considered equivalent to each other.

[0102] Several R / W pairs 222 may be present, such as 8, 16, 32 pairs, etc. The R / W pairs222 as shown are linearly aligned in a direction generally perpendicular to a direction of tapetravel thereacross. However, the pairs may also be aligned diagonally, etc. Servo readers 212 are positioned on the outside of the array of R / W pairs, the function of which is well known. FIG.27 is a schematic of a tilted head concept for tape dimensional stability (TDS) compensation, in accordance with an exemplary approach.

[0103] Generally, the magnetic tape medium moves in either a forward or reversedirection as indicated by arrow 220. The magnetic tape medium and head assembly 211 operate in a transducing relationship in the manner well-known in the art. The head assembly211 includes two thin-film modules 224 and 226 of generally identical construction.

[0104] Modules 224 and 226 are joined together with a space present between closures204B thereof (partially shown) to form a single physical unit to provide read-while-writecapability by activating the write transducer of the leading module and read transducer of thetrailing module aligned with the write transducer of the leading module parallel to thedirection of tape travel relative thereto. When a module 224, 226 of a magnetic tape head 211is constructed, layers are formed in the gap 218 created above an electrically conductivesubstrate 204A (partially shown), e.g., of AlTiC, in generally the following order for the R / Wpairs 222: an insulating layer 236, a first shield 232 typically of an iron alloy such as NiFe(e.g., ~80 / 20 at% NiFe, also known as permalloy), cobalt zirconium tantalum (CZT) or Al-Fe-Si (Sendust), a sensor 234 for sensing a data track on a magnetic medium, a second shield238 typically of a nickel-iron alloy (e.g., permalloy), first and second writer poles 228, 230,and a coil (not shown). The sensor may be of any known type, including those based onmagnetoresistive (MR), GMR, AMR, tunneling magnetoresistance (TMR), etc.

[0105] The first and second writer poles 228, 230 may be fabricated from high magneticmoment materials such as CoFe. Note that these materials are provided by way of example only, and other materials may be used. Additional layers such as insulation between the shields and / or pole tips and an insulation layer surrounding the sensor may be present. Illustrative materials for the insulation include alumina and other oxides, insulative polymers, etc.

[0106] The configuration of the tape head 211, according to one approach, includesmultiple modules, preferably three or more. In a write-read-write (W-R-W) head, outermodules for writing flank one or more inner modules for reading. Referring to FIG.3,depicting a W-R-W configuration, the outer modules 252, 256 each include one or morearrays of write transducers 260. The inner module 254 of FIG. 3 includes one or more arraysof read transducers 258 in a similar configuration. Variations of a multi-module head includea R-W-R head (FIG. 4), a R-R-W head, a W-W-R head, etc. In yet other variations, one ormore of the modules may have read / write pairs of transducers. Moreover, more than threemodules may be present. In further approaches, two outer modules may flank two or moreinner modules, e.g., in a W-R-R-W, a R-W-W-R arrangement, etc. For simplicity, a W-R-W head is used primarily herein to exemplify approaches of the present invention. One skilled in the art apprised with the teachings herein will appreciate how permutations of the present invention would apply to configurations other than a W-R-W configuration.

[0107] FIG. 5 illustrates a magnetic head 211 according to one aspect of the presentinvention that includes first, second and third modules 302, 304, 306 each having a tape bearing surface 308, 310, 312 respectively, which may be flat, contoured, etc. Note that while the term “tape bearing surface” appears to imply that the surface facing the tape 315 is inphysical contact with the tape bearing surface, this is not necessarily the case. Rather, only aportion of the tape may be in contact with the tape bearing surface, constantly orintermittently, with other portions of the tape riding (or “flying”) above the tape bearingsurface on a layer of air, sometimes referred to as an “air bearing”. The first module 302 will be referred to as the “leading” module as it is the first module encountered by the tape in athree module design for tape moving in the indicated direction. The third module 306 will bereferred to as the “trailing” module. The trailing module follows the middle module and is the last module seen by the tape in a three module design. The leading and trailing modules 302,306 are referred to collectively as outer modules. Also note that the outer modules 302, 306 will alternate as leading modules, depending on the direction of travel of the tape 315.

[0108] In one approach, the tape bearing surfaces 308, 310, 312 of the first, second andthird modules 302, 304, 306 lie on about parallel planes (which is meant to include parallel and nearly parallel planes, e.g., between parallel and tangential as in FIG.6), and the tape bearing surface 310 of the second module 304 is above the tape bearing surfaces 308, 312 of the first and third modules 302, 306. As described below, this has the effect of creating the desired wrap angle α2of the tape relative to the tape bearing surface 310 of the second module 304.

[0109] Where the tape bearing surfaces 308, 310, 312 lie along parallel or nearly parallelyet offset planes, intuitively, the tape should peel off of the tape bearing surface 308 of theleading module 302. However, the vacuum created by a skiving edge 318 of the leadingmodule 302 has been found by experimentation to be sufficient to keep the tape adhered tothe tape bearing surface 308 of the leading module 302. A trailing edge 320 of the leadingmodule 302 (the end from which the tape leaves the leading module 302) is the approximate reference point which defines the wrap angle α2 over the tape bearing surface 310 of the second module 304. The tape stays in close proximity to the tape bearing surface until closeto the trailing edge 320 of the leading module 302. Accordingly, transducers 322 may belocated near the trailing edges of the outer modules 302, 306. These approaches are particularly adapted for write-read-write applications.

[0110] A benefit of this and other approaches described herein is that, because the outermodules 302, 306 are fixed at a determined offset from the second module 304, the inner wrap angle α2 is fixed when the modules 302, 304, 306 are coupled together or are otherwise fixed into a head. The inner wrap angle α2 is approximately tan-1(δ / W) where δ is the height difference between the planes of the tape bearing surfaces 308, 310 and W is the width between the opposing ends of the tape bearing surfaces 308, 310. An illustrative inner wrap angle α2 is in a range of about 0.3° to about 1.1°, though can be any angle required by the design.

[0111] Beneficially, the inner wrap angle α2 on the side of the module 304 receiving thetape (leading edge) will be larger than the inner wrap angle α3 on the trailing edge, as the tape315 rides above the trailing module 306. This difference is generally beneficial as a smaller α3 tends to oppose what has heretofore been a steeper exiting effective wrap angle.

[0112] Note that the tape bearing surfaces 308, 312 of the outer modules 302, 306 arepositioned to achieve a negative wrap angle at the trailing edge 320 of the leading module302. This is generally beneficial in helping to reduce friction due to contact with the trailing edge 320, provided that proper consideration is given to the location of the crowbar regionthat forms in the tape where it peels off the head. This negative wrap angle also reducesflutter and scrubbing damage to the elements on the leading module 302. Further, at the trailing module 306, the tape 315 flies over the tape bearing surface 312 so there is virtuallyno wear on the elements when tape is moving in this direction. Particularly, the tape 315entrains air and so will not significantly ride on the tape bearing surface 312 of the third module 306 (some contact may occur). This is permissible, because the leading module 302 is writing while the trailing module 306 is idle.

[0113] Writing and reading functions are performed by different modules at any giventime. In one approach, the second module 304 includes a plurality of data and optional servo readers 331 and no write transducers. The first and third modules 302, 306 include a plurality of write transducers 322 and no data read transducers, with the exception that the outer modules 302, 306 may include optional servo readers. The servo readers may be used to position the head during reading and / or writing operations. The servo reader(s) on each module are typically located towards the end of the array of read transducers or write transducers.

[0114] By having only read transducers or side by side write transducers and servoreaders in the gap between the substrate and closure, the gap length can be substantially reduced. Typical heads have piggybacked read transducers and write transducers, where thewrite transducer is formed above each read transducer. A typical gap is 20-35 microns.However, irregularities on the tape may tend to droop into the gap and create gap erosion. Thus, the smaller the gap the better. The smaller gap enabled herein exhibits fewer wear related problems.

[0115] In some approaches, the second module 304 has a closure, while the first andthird modules 302, 306 do not have a closure. Where there is no closure, preferably a hard coating is added to the module. One preferred coating is diamond-like carbon (DLC).

[0116] In the approach shown in FIG. 5, the first, second, and third modules 302, 304,306 each have a closure 332, 334, 336, which extends the tape bearing surface of the associated module, thereby effectively positioning the read / write elements away from theedge of the tape bearing surface. The closure 332 on the second module 304 can be a ceramicclosure of a type typically found on tape heads. The closures 334, 336 of the first and thirdmodules 302, 306, however, may be shorter than the closure 332 of the second module 304 asmeasured parallel to a direction of tape travel over the respective module. This enablespositioning the modules closer together. One way to produce shorter closures 334, 336 is tolap the standard ceramic closures of the second module 304 an additional amount. Another way is to plate or deposit thin film closures above the elements during thin film processing. For example, a thin film closure of a hard material such as Sendust or nickel-iron alloy (e.g., 45 / 55) can be formed on the module.

[0117] With reduced-thickness ceramic or thin film closures 334, 336 or no closures onthe outer modules 302, 306, the write-to-read gap spacing can be reduced to less than about 1mm, e.g., about 0.75 mm, or 50% less than commonly-used linear tape open (LTO) tape headspacing. The open space between the modules 302, 304, 306 can still be set to approximately0.5 to 0.6 mm, which in some approaches is ideal for stabilizing tape motion over the secondmodule 304.

[0118] Depending on tape tension and stiffness, it may be desirable to angle the tapebearing surfaces of the outer modules relative to the tape bearing surface of the secondmodule. FIG. 6 illustrates an approach where the modules 302, 304, 306 are in a tangent ornearly tangent (angled) configuration. Particularly, the tape bearing surfaces of the outer modules 302, 306 are about parallel to the tape at the desired wrap angle α2 of the second module 304. In other words, the planes of the tape bearing surfaces 308, 312 of the outer modules 302, 306 are oriented at about the desired wrap angle α2of the tape 315 relative to the second module 304. The tape will also pop off of the trailing module 306 in this approach, thereby reducing wear on the elements in the trailing module 306. These approaches are particularly useful for write-read-write applications. Additional aspects of these approaches are similar to those given above.

[0119] Typically, the tape wrap angles may be set about midway between the approachesshown in FIGS. 5 and 6.

[0120] FIG. 7 illustrates an approach where the modules 302, 304, 306 are in anoverwrap configuration. Particularly, the tape bearing surfaces 308, 312 of the outer modules 302, 306 are angled slightly more than the tape 315 when set at the desired wrap angle α2 relative to the second module 304. In this approach, the tape does not pop off of the trailing module, allowing it to be used for writing or reading. Accordingly, the leading and middle modules can both perform reading and / or writing functions while the trailing module can readany just-written data. Thus, these approaches are preferred for write-read-write, read-write-read, and write-write-read applications. In the latter approaches, closures should be wider than the tape canopies for ensuring read capability. The wider closures may require a widergap-to-gap separation. Therefore, a preferred approach has a write-read-write configuration,which may use shortened closures that thus allow closer gap-to-gap separation.

[0121] Additional aspects of the approaches shown in FIGS. 6 and 7 are similar to thosegiven above.

[0122] A 32 channel version of a multi-module tape head 211 may use cables 350having leads on the same or smaller pitch as current 16 channel piggyback LTO modules, or alternatively the connections on the module may be organ-keyboarded for a 50% reduction incable span. Over-under, writing pair unshielded cables may be used for the write transducers,which may have integrated servo readers.

[0123] The outer wrap angles α1 may be set in the drive, such as by guides of any typeknown in the art, such as adjustable rollers, slides, etc. or alternatively by outriggers, which are integral to the head. For example, rollers having an offset axis may be used to set the wrap angles. The offset axis creates an orbital arc of rotation, allowing precise alignment of the wrap angle α1.

[0124] To assemble any of the approaches described above, conventional u-beamassembly can be used. Accordingly, the mass of the resultant head may be maintained or evenreduced relative to heads of previous generations. In other approaches, the modules may be constructed as a unitary body. Those skilled in the art, armed with the present teachings, will appreciate that other known methods of manufacturing such heads may be adapted for use inconstructing such heads. Moreover, unless otherwise specified, processes and materials oftypes known in the art may be adapted for use in various approaches in conformance with theteachings herein, as would become apparent to one skilled in the art upon reading the present disclosure.

[0125] As a tape is run over a module, it is preferred that the tape passes sufficientlyclose to magnetic transducers on the module such that reading and / or writing is efficiently performed, e.g., with a low error rate. According to some approaches, tape tenting may be used to ensure the tape passes sufficiently close to the portion of the module having the magnetic transducers. To better understand this process, FIGS.8A-8C illustrate the principles of tape tenting. FIG.8A shows a module 800 having an upper tape bearing surface 802 extending between opposite edges 804, 806. A stationary tape 808 is shown wrapping around the edges 804, 806. As shown, the bending stiffness of the tape 808 lifts the tape off of the tape bearing surface 802. Tape tension tends to flatten the tape profile, as shown in FIG.8A. Where tape tension is minimal, the curvature of the tape is more parabolic than shown.

[0126] FIG. 8B depicts the tape 808 in motion. The leading edge, i.e., the first edge thetape encounters when moving, may serve to skive air from the tape, thereby creating a subambient air pressure between the tape 808 and the tape bearing surface 802. In FIG.8B, the leading edge is the left edge and the right edge is the trailing edge when the tape is moving left to right. As a result, atmospheric pressure above the tape urges the tape toward the tape bearing surface 802, thereby creating tape tenting proximate each of the edges. The tape bending stiffness resists the effect of the atmospheric pressure, thereby causing the tape tenting proximate both the leading and trailing edges. Modeling predicts that the two tents are very similar in shape.

[0127] FIG. 8C depicts how the subambient pressure urges the tape 808 toward the tapebearing surface 802 even when a trailing guide 810 is positioned above the plane of the tape bearing surface.

[0128] It follows that tape tenting may be used to direct the path of a tape as it passesover a module. As previously mentioned, tape tenting may be used to ensure the tape passes sufficiently close to the portion of the module having the magnetic transducers, preferably such that reading and / or writing is efficiently performed, e.g., with a low error rate.

[0129] Magnetic tapes (also referred to as tapes, magnetic recording tapes, tape media,and the like) may be stored in tape cartridges that are, in turn, stored at storage slots or thelike inside a data storage library. The tape cartridges may be stored in the library such that they are accessible for physical retrieval. In addition to magnetic tapes and tape cartridges, data storage libraries may include data storage drives that store data to, and / or retrieve data from, the magnetic tapes. Moreover, tape libraries and the components included therein may implement a file system which enables access to tape and data stored on the tape.

[0130] File systems may be used to control how data is stored in, and retrieved from,memory. Thus, a file system may include the processes and data structures that an operating system uses to keep track of files in memory, e.g., the way the files are organized in memory.Linear Tape File System (LTFS) is an exemplary format of a file system that may beimplemented in a given library in order to enable access to compliant tapes. It should beappreciated that various approaches herein can be implemented with a wide range of filesystem formats, including for example IBM® Spectrum® Archive Library Edition (LTFSLE) (IBM and all IBM–based trademarks and logos are trademarks or registered trademarksof International Business Machines Corporation and / or its affiliates). However, to provide acontext, and solely to assist the reader, some of the approaches below may be described withreference to LTFS, which is a type of file system format. This has been done by way ofexample only, and should not be deemed limiting on the invention defined in the claims.

[0131] A tape cartridge may be “loaded” by inserting the cartridge into the tape drive,and the tape cartridge may be “unloaded” by removing the tape cartridge from the tape drive. Once loaded in a tape drive, the tape in the cartridge may be “threaded” through the drive by physically pulling the tape (the magnetic recording portion) from the tape cartridge, and passing it above a magnetic head of a tape drive. Furthermore, the tape may be attached on atake-up reel (e.g., see 205 of FIG. 2A above) to move the tape over the magnetic head.

[0132] Once threaded in the tape drive, the tape in the cartridge may be “mounted” byreading metadata on a tape and bringing the tape into a state where the LTFS is able to use thetape as a constituent component of a file system. Moreover, in order to “unmount” a tape, metadata is preferably first written on the tape (e.g., as an index), after which the tape may be removed from the state where the LTFS is allowed to use the tape as a constituent component of a file system. Finally, to “unthread” the tape, the tape is unattached from the take-up reel and is physically placed back into the inside of a tape cartridge again. The cartridge may remain loaded in the tape drive even after the tape has been unthreaded, e.g., waiting for another read and / or write request. However, in other instances, the tape cartridge may be unloaded from the tape drive upon the tape being unthreaded, e.g., as described above.

[0133] Magnetic tape is a sequential access medium. Thus, new data is written to thetape by appending the data at the end of previously written data. It follows that when data is recorded in a tape having only one partition, metadata (e.g., allocation information) is continuously appended to an end of the previously written data as it frequently updates and is accordingly rewritten to tape. As a result, the rearmost information is read when a tape is first mounted in order to access the most recent copy of the metadata corresponding to the tape. However, this introduces a considerable amount of delay in the process of mounting a given tape.

[0134] To overcome this delay caused by single partition tape mediums, the LTFSformat includes a tape that is divided into two partitions, which include an index partition anda data partition. The index partition may be configured to record metadata (meta information),e.g., such as file allocation information (Index), while the data partition may be configured torecord the body of the data, e.g., the data itself.

[0135] Looking to FIG. 9, a magnetic tape 900 having an index partition 902 and a datapartition 904 is illustrated, according to one approach. As shown, data files and indexes arestored on the tape. The LTFS format allows for index information to be recorded in the indexpartition 902 at the beginning of tape 906, as would be appreciated by one skilled in the artupon reading the present description.

[0136] As index information is updated, it preferably overwrites the previous version ofthe index information, thereby allowing the currently updated index information to beaccessible at the beginning of tape in the index partition. According to the specific exampleillustrated in FIG. 9, a most recent version of metadata Index 3 is recorded in the indexpartition 902 at the beginning of the tape 906. Conversely, all three versions of metadataIndex 1, Index 2, Index 3 as well as data File A, File B, File C, File D are recorded in the datapartition 904 of the tape. Although Index 1 and Index 2 are old (e.g., outdated) indexes,because information is written to tape by appending it to the end of the previously writtendata as described above, these old indexes Index 1, Index 2 remain stored on the tape 900 inthe data partition 904 without being overwritten.

[0137] The metadata may be updated in the index partition 902 and / or the data partition904 the same or differently depending on the desired approach. According to someapproaches, the metadata of the index and / or data partitions 902, 904 may be updated inresponse to the tape being unmounted, e.g., such that the index may be read quickly from theindex partition when that tape is mounted again. The metadata is preferably also written in thedata partition 904 so the tape may be mounted using the metadata recorded in the datapartition 904, e.g., as a backup option.

[0138] According to one example, which is no way intended to limit the invention, LTFSLE may be used to provide the functionality of writing an index in the data partition when auser explicitly instructs the system to do so, or at a time designated by a predetermined period which may be set by the user, e.g., such that data loss in the event of sudden power stoppage can be mitigated.

[0139] As mentioned above, magnetic tape is generally compliant with some predefinedformat, such as LTO 9, LTO 10, etc. A format may specify servo track spacing, guard band location, number of tracks, and so on. Magnetic heads are designed to comply with a particular format (or formats e.g., via reverse compatibility). Formats are generally available in the literature, and therefore readily available to interested parties. Various approachesdescribed herein may correspond to extant formats, modified versions of extant formatscreated according to the teachings herein, and / or creation of a new format that could be, in relevant part, specified by one skilled in the art after being apprised of the present disclosure and the teachings herein.

[0140] Servo bands compliant with the desired format are written on the magnetic tape atthe factory to ensure precise positioning of the servo tracks within the servo bands under idealconditions to ensure consistency of the servo pattern, proper and consistent spacing, and tominimize the detrimental effects of tape lateral expansion and contraction. Moreover, servo tracks are not written by customer tape drives due to a variety of reasons, such as the inherent variability between writer spacing from module to module and drive to drive, the inability toensure optimal conditions that avoid tape lateral expansion or contraction, and so on, aswould be apparent to unskilled in the art. Indeed, customer-level tape drives do not typically have built-in capabilities to write servo tracks, e.g., they do not have servo writers. It bears mention that some tape drives are able to write High Definition (HD) servo tracks that supplement the prewritten data band. The present disclosure is directed to servo bandsprewritten on magnetic tapes according to a particular format.

[0141] It follows that the servo tracks prewritten on a magnetic tape are used throughoutthe life of the magnetic tape. Conventional wisdom has been to protect the servo tracks from overwrite to ensure their integrity, as damage to the servo tracks may render data on the tape unreadable. Accordingly, as shown in FIG.10, which is a partial representative view of amagnetic tape 1000 factory-formatted according to the LTO 10 format having two factory-written servo bands 1002, 1004 (three other servo bands not shown) flanking a data band area1006. Unwritable guard bands 1008, 1010 are specified as being positioned between the databand area 1006 and each servo band 1002, 1004 adjacent thereto. The guard bands 1008,1010 are areas on the tape which are not written to, as specified by the format, to protect theservo bands 1002, 1004 from accidental overwrite.

[0142] Given that servo bands compliant with a predefined format are prewritten ontothe magnetic tape typically at the magnetic tape factory, prior to the present invention, onlytape drives designed to operate with the predefined format directly or via backwardcompatibility have been able to write data to a magnetic tape. Tape drives not designed tooperate with the format of the tape have heretofore not been able to write to such a magnetictape using the servo tracks of the prewritten servo bands. The servo bands may have any typeof known timing based servo pattern therein.

[0143] There has therefore been a need to extend the use magnetic tapes formatted for agiven media format across noncompliant products using different read / write head designs.

[0144] Now referring to FIG. 11, a flowchart of a method 1100 for enabling reuse ofmagnetic recording tape media with products not designed for the format of the tape media is shown according to one approach. The method 1100 may be performed in accordance withthe present invention in any of the environments depicted in FIGS.1-10, among others, invarious approaches. Of course, more, or fewer operations than those specifically described inFIG. 11 may be included in method 1100, as would be understood by one of skill in the artupon reading the present descriptions.

[0145] Each of the steps of the method 1100 may be performed by any suitablecomponent of the operating environment. For example, in various approaches, the method 1100 may be partially or entirely performed by a tape drive, a tape library, or some other device having one or more processors therein. The processor, e.g., processing circuit(s), chip(s), and / or module(s) implemented in hardware and / or software, and preferably having at least one hardware component may be utilized in any device to perform one or more steps of the method 1100. Illustrative processors include, but are not limited to, a central processing unit (CPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), etc., combinations thereof, or any other suitable computing device known in the art.

[0146] As shown in FIG. 11, method 1100 includes operation 1102, where a tape drivereceives a command to write data.

[0147] In operation 1104, the tape drive writes data tracks to a data band of a magnetictape having servo bands flanking the data band. The tape drive may be of conventionaldesign, except that writing is performed using a magnetic head that is not designed for, e.g.,compliant with, a format of the magnetic tape. For example, the layout, pitch (center-to-centerspacing), etc. of the magnetic write transducers of the head may be different than a headconfigured to write tracks having a pitch specified by the format to thereby write data tracksat a different pitch than specified by the format, would write to areas such as guard bands that are specified as unwritable by the format, etc.

[0148] The writing includes overwriting a portion of each of the servo bands with thedata tracks. As mentioned above, it has conventionally been considered unacceptable tooverwrite any portion of a prewritten servo band with data. For this reason, the aforementioned guard bands are specified by all relevant tape formats to protect the servo bands. Accordingly, this method 1100 proceeds contrary to conventional wisdom, thereby enabling tape drive products not designed for the particular format of the tape to not only write to the magnetic tape, but in fact use more area of the tape for writing data, thereby potentially increasing the amount of data storable on the tape. Moreover, because the data is written in the format for which the tape drive is configured, the same drive or another drive configured in the format of the drive can read the data from the magnetic tape.

[0149] FIG. 12 is a partial representative view of a magnetic tape 1000 having twoprewritten servo bands 1002, 1004 (other servo bands not shown). As shown, upon performing the method 1100 of FIG.11 with a tape drive that is not compliant with LTO 10, the resulting data band 1202 extends into one or both of the servo bands 1002, 1004.

[0150] As shown in FIG. 12, centerlines 1204 of the portions 1206 of the servo bandsused during the writing are original centerlines of the servo bands, where the originalcenterlines extend along a longitudinal axis of the recording tape and are each located at alateral midpoint of the respective original servo band 1002, 1004. Note that each “original” servo band 1002, 1004 is the servo band in its original width for the format for which intended, before being overwritten. To exemplify the remaining servo band, data bands 1210, 1212 written according to the method 1100 of FIG.11 are also shown above and below.

[0151] As described in more detail below, the drive that is not designed for the format ofthe tape may have one servo reader on each side of the array of write transducers, or more than one servo reader on each side of the array of write transducers. In one approach, theeffective (center-to-center) pitch of a pair of the servo readers of the magnetic head usedsimultaneously during the writing matches a servo reader pitch specification of the format ofthe magnetic tape.

[0152] An “effective pitch,” as used herein refers to the pitch as measured perpendicularto the direction of tape travel. Thus, on the tape, the effective pitch of the servo bands is the actual pitch of the servo bands, while the effective pitch of the data tracks is the actual pitch of the data tracks. On a non-tilted head, the effective pitch of the servo readers is the actual pitch of the servo readers. On a tilted head, the effective pitch of the servo readers is less than the actual pitch of the servo readers. Similarly, on a tilted head, the effective pitch of the read or write transducers is less than the actual pitch of the transducers. The pitch specified by a format generally refers to the effective pitch. Thus, for example, a transducer pitch specified by a format can be considered to be the pitch that provides an effective transducer pitch to match the data track pitch specified by the format. Likewise, a servo reader pitch specified by a format can be considered to be the pitch that provides the effective servo reader pitch that matches the servo reader pitch specified by the format. Examples are provided below.

[0153] In one specific example, the servo readers that are simultaneously used duringthe writing (e.g., one servo reader on each servo band) may have a pitch approximating thatspecified in LTO 10 (e.g., 2815.4 microns), or if the head is tilted, an actual pitch that causesthe lateral distance (effective pitch) between the servo readers as measured perpendicular tothe direction of tape travel thereacross to match the effective pitch specified in LTO 10 (e.g.,2815.4 microns) at the nominal tilt angle.

[0154] In one approach, the magnetic head has one servo reader positioned on one sideof the array of magnetic write transducers and one servo reader positioned on an opposite side of the array of magnetic write transducers on the same module. See, e.g., servo readers 212 of FIG.2E. In this approach, the pair of servo readers is used to position the writers during all writing within a given data band.

[0155] In another approach, the magnetic head has at least two servo readers positionedon one side of the array of magnetic write transducers and at least two servo readerspositioned on an opposite side of the array of magnetic write transducers on the same module.For example, each side of the array in FIG.2E may have two or more servo readers 212, e.g., groups of two or more servo readers positioned adjacent one another along the cross-trackdirection, one group on each side of the array of write transducers, and preferably generallyaligned therewith in the cross-track direction. The tape drive is configured to use a first one of the servo readers positioned on each side of the array for writing data tracks in a first portion of the data band and to use a second one of the servo readers positioned on each side of the array for writing data tracks in a second portion of the data band that is different than the firstportion. Thus, for instance, the pair of first servo readers may be used to write data tracksstarting at a lowermost lateral location of the write transducers in the data band on the magnetic tape. As data tracks are written, the first servo readers move across the respective servo band until positioning control is transitioned to use of the second servo readers to continue the writing. This feature enables more overwrite of the servo band (and thus less remaining width of the servo band) by using one pair of servo readers for part of the writing(e.g., when other pair(s) of the servo readers are not over the servo bands) and then anotherpair of the servo readers for another part of the writing (e.g., when the first pair of servo readers no longer overlies the servo bands).

[0156] Some approaches may have three pairs of servo readers (e.g., three servo readerson each side of the data band), four pairs, and so on. The greater the number of pairs of servo readers, the less distance across the servo bands need be traversed by a given pair of servo readers, which in turn reduces the amount of servo bands that must be retained.

[0157] In further approaches, the actual pitch, or effective pitch if on a tilted head,between pairs of servo readers used during a given writing operation may be less than theservo reader pitch specified by the format for the magnetic tape, which typically correspondsto the actual pitch of adjacent servo bands. Accordingly, centerlines of the portions of theservo bands used during the writing are offset from original centerlines of the servo bands.

[0158] In some approaches, the effective pitch of servo readers of a magnetic head usedsimultaneously during the writing does not match a servo reader pitch specification of the format of the magnetic tape. FIG.13 is a partial representative view of a magnetic tape 1000 having two prewritten servo bands 1002, 1004 (other servo bands not shown). As shown,upon performing the method 1100 of FIG. 11 with a tape drive having an effective servoreader pitch (e.g., 2723.4 microns) that is less than the pitch (2815.4 microns) specified inLTO 10, the resulting data band 1202 extends into one or both of the servo bands 1002, 1004, and centerlines 1302, 1304 of the portions 1306, 1308 of the servo bands used during the writing are offset from original centerlines 1204 of the servo bands.

[0159] According to one approach, the overwrite depicted in FIGS. 12-13 may beachieved by increasing the average effective center-to-center pitch of the write transducers above the pitch specified in the format. For example, LTO 10 specifies 32 data tracks writtenconcurrently onto tape at a pitch of 81.99 microns. The pitch of the transducers on an LTO10-compliant head are positioned to read and write the tracks at this pitch. Thus, an exemplary on-head transducer pitch for an LTO 10-compliant head is 83.25 microns, wheresuch head is nominally tilted at 10 degrees from perpendicular to the direction of tape travelthereacross (83.25*cos(10deg)=81.99). The pitch in the noncompliant head may be larger, e.g., 32 write transducers at a pitch of 86.15 microns, thereby causing the data band 1202 toextend into each original servo band by approximately 17 microns with the same tilt.

[0160] According to another approach, the overwrite depicted in FIGS. 12-13 may beachieved by increasing the number of active write transducers used during the writing. Forexample, LTO 10 specifies writing at an effective pitch of 81.99 microns, and thus specifiesan on-head transducer pitch of 83.25 microns for a head having a tilt of 10º. The number of write transducers in the array of the noncompliant head may be larger, e.g., 48, 64, etc. The pitch of the write transducers in an array of the noncompliant head may be a proportional division product of the pitch specified by the format, e.g., 64 write transducers in an array positioned at one half the specification pitch of a format specifying 32 write transducers. Inother approaches, the effective pitch of the write transducers in an array of the noncomplianthead may be larger than the aforementioned division product.

[0161] Any other mechanism or configuration for overwriting a portion of one or bothservo bands flanking a data band that would become apparent to unskilled in the art after reading the present disclosure may be used in various approaches.

[0162] In some approaches, the prewritten servo bands of a magnetic tape are notoverwritten by a magnetic head that is not designed for a format of the magnetic tape, but most (e.g., at least 90%) or all of the area occupied by the guard bands specified by the format is written to. To exemplify, FIG.14 is a partial representative view of a magnetic tape 1000 having two prewritten servo bands 1002, 1004 (other servo bands not shown). As shown, thedata band 1402 extends nearly to both flanking servo bands 1002, 1004, with perhaps a smallamount of unwritten area between the data band 1402 and one or both servo bands 1002,1004.

[0163] Now referring to FIG. 15, a flowchart of a method 1500 for reusing recordingtape media with products not designed for the format of the magnetic tape media is shown according to one approach. The method 1500 may be performed in accordance with the present invention in any of the environments depicted in FIGS.1-14, among others, in variousapproaches. Of course, more, or fewer operations than those specifically described in FIG. 15may be included in method 1500, as would be understood by one of skill in the art upon reading the present descriptions.

[0164] Each of the steps of the method 1500 may be performed by any suitablecomponent of the operating environment. For example, in various approaches, the method 1500 may be partially or entirely performed by a tape drive, a tape library, or some other device having one or more processors therein. The processor, e.g., processing circuit(s), chip(s), and / or module(s) implemented in hardware and / or software, and preferably having at least one hardware component may be utilized in any device to perform one or more steps of the method 1500. Illustrative processors include, but are not limited to, a central processing unit (CPU), an application specific integrated circuit (ASIC), a field programmable gate array(FPGA), etc., combinations thereof, or any other suitable computing device known in the art.

[0165] As shown in FIG. 15, method 1500 includes operation 1502, where a tape drivereceives a command to write data.

[0166] In operation 1504, the tape drive writes data tracks to a data band of a magnetictape having servo bands flanking the data band, the writing being performed using a magnetic head that is not designed for a format of the magnetic tape. An effective pitch of servo readersof the magnetic head used simultaneously during the writing matches a servo reader pitchspecification of the format of the magnetic tape. The servo reader pitch specificationgenerally specifies the effective servo reader pitch to use when performing data operations onthe magnetic tape. For example, the servo reader pitch specification may directly correspond to the pitch of the servo bands on the magnetic tape, e.g., the servo reader pitch specificationmay specify an effective servo reader pitch equal to the pitch of the servo tracks in the servo bands flanking a given data band. An average effective pitch of the write transducers of themagnetic head is greater than a data track pitch specification of the format of the magnetictape.

[0167] In one approach, a portion of one or more of the servo bands is overwritten withdata tracks during the writing, e.g., as depicted in FIGS.12-13.

[0168] In another approach, the servo bands are not overwritten with data tracks duringthe writing, i.e., no part of either servo band is overwritten. For example, the resulting written area may conceptually resemble that shown in FIG.14. The overwrite of the guard bandsdepicted in FIG. 14 may be achieved by increasing the average effective pitch of the writetransducers to increase the pitch of the written tracks above the pitch specified in the format.The proper effective pitch to fill in all areas between the servo bands may be calculated in amanner that would become apparent to one skilled in the after reading the present disclosure.

[0169] According to another approach, the overwrite of the guard bands depicted in FIG.14 may be achieved due to a larger number of active write transducers used during the writingthan specified by the format of the magnetic tape. For example, LTO 10 specifies 32 writetransducers at an effective pitch of 81.99 microns. The number of write transducers in thearray of the noncompliant head may be larger, e.g., 48, 64, etc. The effective pitch of thewrite transducers in an array of the noncompliant head may be a proportional division productof the data track pitch specified by the format, e.g., 64 write transducers in an array positioned at one half the specification pitch of a format specifying 32 simultaneously-written data tracks. In other approaches, the effective pitch of the write transducers in an array of the noncompliant head may be larger than the aforementioned division product.

[0170] An apparatus, in accordance with various approaches, may be a tape drive havinga drive mechanism for passing a magnetic tape over a magnetic head and a controllerelectrically coupled to the magnetic head. The controller is configured to cause the magnetichead to write data tracks to a data band of the magnetic tape, the magnetic tape having servobands flanking the data band, e.g., according to the method 1100 of FIG.11. The apparatusmay be configured to nominally operate with a specific tape format or formats but is alsocapable of writing to a magnetic tape in one mode of operation where the magnetic head isnot designed for the format of the magnetic tape. The writing includes overwriting a portion of each of the servo bands with the data tracks, e.g., using any combination of the methodology presented herein.

[0171] The apparatus may include components and configurations as describedelsewhere herein (see, e.g., FIGS.2A-7, as well as configurations described with reference toFIGS. 12-14). For example, the magnetic head may have a single pair of servo readersflanking the array of write transducers, or at least two servo readers positioned on one side ofthe array of write transducers and at least two servo readers positioned on an opposite side ofthe array of write transducers on a given module. Likewise, as described above, the tape drivemay be configured to use a first one of the servo readers positioned on each side of the arrayfor writing data tracks in a first portion of the data band and to use a second one of the servo readers positioned on each side of the array for writing data tracks in a second portion of the data band that is different than the first portion.

[0172] In some approaches, centerlines of the portions of the servo bands used duringthe writing are original centerlines of the servo bands, where the original centerlines extend along a longitudinal axis of the recording tape and are each located at a lateral midpoint of the respective original servo band (where the original servo band is the servo band in its original width for the format for which intended, before being overwritten).

[0173] In some approaches, the effective pitch of the servo readers used simultaneouslyduring the writing matches the effective servo reader pitch specification of the format of themagnetic tape, where an average effective pitch of write transducers of the magnetic head isgreater than the data track pitch specification, and thus the effective write transducer pitchspecification, of the format of the magnetic tape. In other approaches, centerlines of theportions of the servo bands used during the writing are offset from original centerlines of the servo bands.

[0174] In some approaches, an effective pitch of the servo readers used simultaneouslyduring the writing is less than the effective servo reader pitch specification of the format ofthe magnetic tape, and an average effective pitch of write transducers of the magnetic head isgreater than the data track pitch specification of the format of the magnetic tape.

[0175] In yet another approach, an apparatus includes a drive mechanism for passing amagnetic tape over a magnetic head, and a controller electrically coupled to the magnetichead. The controller is being configured to perform the method 1500 of FIG. 15. As noted inthe description of FIG. 15, the servo bands are not overwritten with data tracks during thewriting in some approaches, and in other approaches, a portion of one or more of the servobands is overwritten with data tracks during the writing.

[0176] In further aspects of the present invention, one or more of the servo bands iscompletely overwritten with data tracks during writing, e.g., while performing the method1100 of FIG. 11 or method 1500 of FIG. 15. To enable this feature, an effective pitch of thepair of servo readers used simultaneously during the writing is greater than the sum of thewidths of two of the data bands on the magnetic tape.

[0177] Moreover, to enable the array of write transducers to fill in the space on themagnetic tape previously occupied by the servo band(s) being completely overwritten, multiple servo readers are preferably positioned on opposite sides of the array, and positioned on the head to enable proper servo-based positioning of the write transducers as they traverse the distance between the servo bands being used during writing. For example, the magnetic head may have at least two servo readers positioned on one side of an array of magnetic write transducers and at least two servo readers positioned on an opposite side of the array of magnetic write transducers on a same module. The tape drive is configured to use a first one of the servo readers positioned on each side of the array for writing a first set of the data tracks and to use a second one of the servo readers positioned on each side of the array for writing a second set of data tracks.

[0178] FIGS. 16-18 illustrate, by way of example, these concepts.

[0179] FIG. 16 is a representation of a servo and data band layout on a magnetic tape1600, as specified by a format. As in the other examples, the servo bands 1602 are prewritten to the magnetic tape. The data bands 1604 are located inside of guard bands 1606 positioned adjacent each servo band 1602.

[0180] FIG. 17 illustrates the magnetic tape 1600 of FIG. 16 in which two of the servobands 1602 are overwritten. As shown, the guard bands are also overwritten. The data bands 1702 now occupy area that is greater than two of the data bands 1604 of FIG.16.

[0181] FIG. 18 depicts a representation of a magnetic head 1800 that wrote the databands 1702 of FIG.17. Two sets 1802 of at least two servo readers are positioned on either side of an array 1804 of write transducers.

[0182] The data written according to the various approaches described herein may beread back using the same tape drive, which presumably has an array of read transducers with an effective pitch approximating the effective pitch of the write transducers that wrote the data to the magnetic tape during the writing. The data may also be read back by another tape drive having an array of read transducers with an effective transducer pitch approximating the effective pitch of the write transducers that wrote the data to the magnetic tape during the writing.

[0183] Design Parameters and Examples

[0184] The following description provides further information and exemplary designimplementation details usable with some or all of the foregoing aspects of the presentinvention. The following description includes specific examples and implementation detailsthat are provided by way of example only and are not intended to be limiting on the appendedclaims.

[0185] Extant Magnetic Tape Media

[0186] Extant tape media used for data storage has several major regions: two (2) edgeguard bands on either end of tape having a width ^^^^^; ^^^data bands (1 or more); and^^^ = ^^^ + 1 servo bands. No information resides in the edge guard bands. Data resides inthe data bands and is written by write transducers (also referred to as write elements) and readby read transducers (also referred to as read elements). The servo bands contain pre-writteninformation about the location of the servo element within the servo band. The servo readersread the information in the servo band and use it to determine the location of the read andwrite transducers within the band. The tape heads include read transducers, write transducersand servo readers. Write transducers write data to the media, read transducers read the writtendata, all within the data bands. Servo readers are positioned within the servo bands which areon either side of a data band. A servo band has a width, ^^^ , and a data band has a width,^^^ . Excluding any buffers, the width of tape, ^^^^^ , is the sum of the above mentionedregions:

[0188] The data band width is given by:

[0189] ^^^ = ^^ ∙ ^^^ 2

[0190] The tracks are written with a write transducer of a width ^^ and read by a readtransducer of width ^^ . The final tracks are separated by a track pitch distance, ^^^ which isless than ^^, a process termed shingled writing. A tape head has ^^elements (read and write transducers) and a number or read / write channels, ^^^. ^^is usually equal to ^^^or ^^^+1. For simplicity in this discussion, assume that ^^ and ^^^ are equal. On a tape module, thetransducers (elements) are separated by a distance, ^^^ or element pitch. Accordingly, for asingle write pass of the tape, ^^tracks of width ^^are written and are separated by the element pitch distance, ^^^. On the next pass, the location of the write transducers is stepped over by ^^^and another row of data is written of width ^^. The previously written track is partially written over, leaving data from the previous path with a width of ^^^(shingling).Ideally (excluding buffers and physical fluctuations), then, each write transducer can write^^^^ tracks within the region spanning the element pitch minus the write transducer width:

[0191] (^^^^ − 1) ∙ ^^^ = ^^^ − ^^ 3a

[0192] or

[0194] In the simplest case, only one servo reader is placed on either end of the module,flanking the ^^ elements. The servo readers would then need to move across the servo band adistance equal to this motion. Ideally, (excluding buffers and physical fluctuations), when theservo reader moves across the width of the servo band (^^^), the read transducers will moveacross the element pitch, being placed half a track pitch (^^^) from either end of the element pitch. Thus,

[0195] ^^^ − ^^ = ^^^ − ^^^ , 4a

[0196] or

[0197] ^^^ = ^^^ + ^^ − ^^^ . 4b

[0198] This is the densest packing of the data.

[0199] The servo readers are separated from the nearest element (S1-to-E1 and S2-to-^^^) by ^^^ . In the ideal case, ^^^ is calculated in order to place the edge of the servo readerat the top of the servo band and the read transducer centered half a track pitch (^^^) from thetop of the data band:

[0201] The head span from one servo reader to the next is given by:

[0203] The servo band-to-servo band spacing is then ^^^^^^^^^ . Combining 1, 2 and 4byields:

[0205] Again, in the absence of buffers, the tape media and head are then designed withthe parameters: ^^^^^ , ^^^^^ , ^^^, ^^^^^^^^^ , and ^^^. The heads are designed with theparameters: ^^, ^^^and ^^^. ^^, ^^and ^^^and can be modified to achieve the desired capacity using the base design.

[0206] The cost of the wafers used to make the read and write transducers and the cost ofthe servo-band writers are very high. The ability to reuse tape media designed for a given tapehead design with a new tape head design greatly reduces the cost of the media.

[0207] Media Reuse

[0208] As noted in detail above, one methodology of reusing a fixed media design with anew head design is to allow overwrite of at least a portion of one or more servo bands.

[0209] One example of reusing a given magnetic tape for multiple tape head designsinvolves a head with twice the transducers being used for an existing tape drive and mediasystem. One example is a tape head having 64 transducers (or channels) being used withmedia designed for a head with 32 channels, e.g., as specified by the format of the magnetictape. Given a transducer pitch for the 32-channel version,the head span is essentiallytwice the element pitch of the 64 channel version,Equation 7 uses the samenumerator for both 32 and 64 channel versions. The denominator is ~^^^ ∙ ^^, to the 64-channel version will have an element pitch approximately half the value of the 32 channelversion. From Equation 4b, the width of the servo band for the 64 channel version isapproximately half the value of the 32 channel version:

[0211] ^^^^.^^^^.^^~^ 8b

[0212] In actuality, ^^^.^^ may be slightly higher than given by Equation 8a to enablehigher capacity and the full head span can be maintained. The same media may be used withoverwriting of a portion of the servo band. The gain in usable data band is approximately thenumber of servo bands times half the width of ^^^.^^.

[0213] Another example of overwriting a portion of the servo band includes maintainingthe same number of channels but increasing the capacity by increasing the element pitch andconverting from a single servo per data band to dual servo per data band. With a dual servodesign, each servo may be used to write half of the data subband, which is half the elementpitch. As will be shown later, in the absence of buffers, the required servo band would be:

[0215] Comparing 9 to 4b, the gain in usable data band is approximately the number ofservo bands times half the original transducer pitch by overwriting half the servo band. A newhead design would need to be made with a wider element pitch, increasing the current element pitch to fill in the added space. The detailed equations are provided below.

[0216] FIG. 19 is a representation of regions on tape, according to a conventionalformat. Two edge guard bands, each of width ^^^^^, are show, one on either end of the tape.No magnetic information is written in these regions. This is a four data band tape format(^^^=4), labeled DB1 to DB4, each of width ^^^ , and five servo bands, labeled SB1 to SB5,and each of width ^^^ . The servo readers are designed to span the servo band while writingdata within each data band. A buffer is located at either end of a data band (data band guard) of width ^^^^and on either end of the servo band (servo band guard) of width ^^^^. The width of tape is given by Equation 9.9

[0218] The additions in Equation 9 relative to Equation 1 are the servo and data bandguards which act as buffers between the servo bands and the data bands respectively to avoidoverwriting these regions.

[0219] Part (a) of FIG. 20 depicts the media format in raw format from a tape mediasupplier. Shown are the Edge Guard band, five Servo Bands and four Data Bands. Part (b) ofFIG. 20 shows a schematic of the servo pattern in a servo band. The tape runs left-to-right orright-to-left. The servo readers pass over the servo pattern which is located in the Servo Bandregions in part (a) but is shown pictorially in part (b). For a timing-based servo, the timebetween peaks in the servo signal running over the servo pattern enables the drive todetermine the vertical location of the servo within the servo band and thus the read and writetransducers within the data band. For normal operation, the servo motion spans the height ofthe servo band while the write transducer or read transducer motions span the height of thedata sub band, which is approximately the element pitch.

[0220] Part (c) of FIG. 20 shows a partially overwritten servo pattern and a wider DataBand generated by increasing the element pitch adjusting the location of the servo readersappropriately to enable the write transducers to span the element pitch as given by Equations3 and 4. Part (d) is a representation of the partially overwritten servo pattern.

[0221] The span of the data sub bands, and thus the span of the data band, can beincreased further if two servo readers, ^^and ^^, are located in each servo band and the element pitch is increased further. For a 1-band module, there would be a total of two (2) Sand two (2) T servo readers, one S and one T on one side of the array of ^^ write transducersor read transducers, and one S and one T on the other side of the array. With each servo in aservo band used to control (measure) the movement of the elements (data transducers) over half the data sub bands, the required width of the servo band can be essentially cut in half,freeing up more space for the data sub bands (or data band). The element pitch may beincreased to enable the increased data band width.

[0222] Method to Write Data

[0223] Determination of writing process focuses on the sub data bands.

[0224] FIG. 21 is a representation of a Data Band (DB) and Sub Data Bands, SDB. Thedata band is surrounded by two data guard bands, each of width, ^^^^, which act as buffersbetween the data band and the surrounding servo bands. For a tape head with ^^ read and ^^write elements and a drive with ^^^ read / write channels, where ^^ = ^^^, the number of subdata bands is ^^. On the read / writer modules, the transducers are all separated by an elementpitch of width, ^^^. The width of the data band, ^^^, then is given by the number of elements times the element pitch:

[0225] ^^^ = ^^ ∙ ^^^ . 10

[0226] Each SDB has an Outer Buffer on either end with the width, ^^^^^^^ / 2. Thedata is written from the top of the SB to the center on Even Wraps and from the bottom of the SDB to the center on Odd Wraps.

[0227] A total of ^^^^ Wraps (or tracks) are written. One half will be in the Even Wrapsand half will be in the Odd Wraps. For the first Even Wrap, the write transducer top edgeabuts the lower edge of the top Outer Buffer. The data is shingled to a Track Pitch width,^^^. The width of the Even Wrap data region within the DSB will be ^^^ ∙ ^^^^ / 2.Therefore, the write transducer will move a distance, ^^^ , given by:

[0229] An Inner Buffer of width ^^^^^^ is located between the Even and Odd Wrapsregion to ensure that the data in the lower half of the data sub band is not overwritten by thelast Even written track and the data in the upper half of the data sub band is not overwrittenby the last Odd Written track. The bottom of the final shingled track for the Even Wrapsabuts the top of the Inner Buffer. For the first Odd Wrap, the bottom of the write transducer abuts the top of the Outer Buffer at the bottom of the SDB. For the final Odd Wrap, the top ofthe write transducer will be positioned at or slightly below the bottom of the Inner Buffer.This is to ensure that no data is overwritten. The width of the final Odd Wrap will then be thewidth of the write transducer as it is not shingled. The Data Sub Band width is the ElementPitch, which is calculated using Equation 12a:

[0230] ^^^ = (^^^^^ − 1) ∙ ^^^ + ^^ +^^^^^^^ + ^^^^^^. 12a

[0231] Solving for ^^^^^ gives:

[0233] ^^^^^ is a real number. Physically, the number of Wraps an integer, ^^^^. Sincethe number of Even and Odd wraps is the same, ^^^^is and even integer:

[0234] and ^^^^ = 2 ∙ ^^^^^(^^^^^ / 2), 12c

[0236] ^^^^^(^) is the mathematical function which rounds down to the nearest integer.

[0237] The next step is to determine the required width of the servo bands. Two optionsfor servo readers will be discussed. The simplest is a single servo in each servo band (singleservo reader option). The second is using two separate servo readers, one to write the Even Wraps and a second to write the Odd Wraps (dual servo reader option). The two will be discussed below.

[0238] Single Servo Reader Option for ^^ = ^^^

[0239] Using a single servo reader within a servo band when the number of channels isequal to the number of elements, ^^^ = ^^, the width of the servo band and the distancebetween the servo reader and the nearest element, ^^^.^^^^^^, can be explained using FIG.21 Since the center of the reader is^^^^^^^^^^^^^ below the top of the DSB for the first EvenRead wrap and above the bottom of the DSB for the first Odd Read wrap, the read transducerwill move a distance:

[0240] ^^^.^ = ^^^ − ^^^ − ^^^^^^^^ . 13a

[0241] The servo readers move the same distance. The top edge of the servo reader abutsthe top of the Servo Band (SB) for the first Even Read wrap and the bottom edge of the servoabuts the bottom edge of the SB for the first Odd wrap so the center of the servo will befrom the top and bottom edge of the SB for the first Even and Odd wraps respectively. ^^ isthe servo reader width. Thus, the width of the servo band will be:

[0243] The distance between the center of the top servo reader and the center of the firstread transducer can be determined viewing FIG. 22 for the first even read with the distance^^^.^^^^^^ labeled as ^^^.^^^^^:

[0247] By symmetry, the distance from the lower servo reader to the last read transducerwill also be given by Equation 14b. Note that the actual width of the data band is given byEquation 8 for ^^ transducers, but for explanation purposes a single DSB is sufficient andeasier to show pictorially.

[0248] Equation 9 gives ^^^^^ as a function of unknowns ^^^ and ^^^ ; Equations 10and 13b respectively give ^^^ and ^^^ as a function of ^^^. Combining Equations 9, 10and 13b solve for ^^^:

[0252] ^^^ can be determined using Equation 13b using the value for ^^^ fromEquation 15a.

[0253] The Servo-to-Servo span, ^^^^^^^^^^.^^^^, is given by:

[0257] Single Servo Reader Option for ^^ = ^^^ + 1

[0258] Another option is to use a single servo per servo band when the number ofelements is one more than the number of channels, ^^ = ^^^ + 1. FIG. 23 shows aschematic of two servo bands surrounding two sub data bands in the case where N^ = 3 andN^^ = 2. The concept can be expanded to any case where ^^ = ^^^ + 1. The data bandwidth is now given by Equation 17.

[0259] ^^^ = ^^^ ∙ ^^^ = (^^ − 1) ∙ ^^^ . 17

[0260] A total of ^^^^ Wraps (or ^^^^) will be written. One half of the wraps will be inthe Even Wraps written in Forward (Fwd.) direction and half will be in the Odd Wraps for theReverse (Rev.) direction. In the Forward Wraps, the last write transducer is not used, data iswritten in the top half of the Data Sub Bands and the Servo uses the bottom half of the servoband. Thus, the position of the write transducer in the last Even Wrap defines the lowestlocation of the servo reader in the servo band. In the Reverse (Rev) Wraps, the first writetransducer is not used, data is written in the bottom half of the Data Sub Bands and the Servouses the Top half of the servo band. Thus, the position of the write transducer in the last OddWrap defines the highest location of the servo reader in the servo band. The distance theservo readers move, ^^^ , then is given by:

[0261] ^^^^ = ^^^−^^. 18a

[0262] The write transducers move the same distance given as:

[0264] Combining Equations 16a and 16b gives ^^^ .

[0266] FIG. 21 shows the concept for the wraps and Equations 12a-d still determine^^^^. Combining Equation 12b (with ^^^^ = ^^^^^) yields:

[0268] Equation 9 gives ^^^^^with unknowns ^^^ , and ^^^ . Equations 17 and 18drespectively give ^^^, and ^^^in terms of the unknown ^^^. Combining Equations 1, 17 and 18d yield a solution for ^^^:

[0270] The distance between the center of the Top Servo and the center of the first writetransducer, ^^^.^^^^^, can be determined observing FIG. 23 for the Forward Wraps: half theservo width plus the servo band guard, plus Outer Buffer / 2 plus the distance the writetransducer moves in Forward Wraps (Equation 11. ^^^ =∙ ^^^) plus, half thewrite transducer width:

[0272] Taking Equation 20a and replacing ^^^^ with ^^^^^ from Equation 12b yields:

[0274] Note that, for ^^ = ^^^ + 1, (i.e. Odd ^^), The distance of the servo reader tothe nearest element is approximately half the element pitch plus half the servo reader width((^^^ + ^^) / 2) while the Even ^^ case the distance is approximately one element pitch plushalf the servo reader width (^^^ + ^^).

[0275] The Servo-to-Servo span, ^^^^^^^^^^.^^^ , is given by:

[0276] ^^^^^^^^^^.^^^ = 2 · ^^^.^^^^^ + (^^ − 1) · ^^^ . 21a

[0277] ^^^^^^^^^^.^^^ = ^^ · ^^^ + ^^ − ^^^^^^ − ^^^ + 2 · ^^^^ . 21b

[0278] Thus,21c

[0279] Thus, for the two options of Even and the Odd ^^, both the data band width andthe servo-to-servo span values (16c & 21c) are essentially the same.

[0280] Dual Servo Reader Option for ^^ = ^^^

[0281] The dual servo reader option utilizes two servo readers in each servo band,termed ^^^.^^^^^and ^^^.^^^^, representing the distance from the given servo to the nearestelement. FIG. 22 is a schematic of the servo bands and a single sub data band. The length ofthe data band region is ^^^, given by Equation 10. The schematic has the data bandcompressed to a single sub data band, which represents the first sub data band when viewedfrom the top servo band and the last sub data band (^^^^) when viewed from the bottom servoband. The positioning of the write transducer within the sub data band is described above inSection titled “Method to Write Data”.

[0282] Now the positioning of the servo readers will be described. For the Even (Odd)Wraps, SE.Short will span the Top (Bottom) servo band and SE.Long will span the Bottom(Top) servo band. For the Even Wraps, the distance between the center of the top servo readerand the center of the first read transducer can be determined as follows: The highest locationof the servo reader is during first Even Wrap Read (see FIG. 22). The top edge of the topservo reader will abut the lower edge of the top servo band and the read transducer will belocated half a Track Pitch below the top Outer Buffer. Thus the distance from the top servoreader, S.Short, to the first read transducer, ^^^.^^^^^, will be:

[0284] This is the same Equation as used for the single servo reader option, but ^^^ willbe different as shown below. Here is where the difference occurs. For the first Even Wrap, thetop edge of the servo reader used in the lower servo band will abut the lower edge of the topservo band guard in that servo band. The separation from the last read transducer to the lowerservo reader, S.Long, is labeled ^^^.^^^^ since it is further from the last read transducer than^^^.^^^^^is from the first read transducer:

[0286] The primary dimension determining the distance between the servo reader andthe closest read transducer is ^^^ for ^^^.^^^^^ and ^^^ for ^^^.^^^^ . Since each pair ofservo readers only spans half the data band for the even wraps, ^^^~^^^ / 2, as will beshown below.

[0287] The Odd Wraps will also use a pair of servo readers, and by symmetry, they willhave the same dimensions as the Even Wraps, except they will be reversed, with ^^^.^^^^being in the top servo band and ^^^.^^^^^ being in the bottom servo band. Thus, the order ofelements from top to bottom will be: S.Long, S.Short, ^^elements, S.Short, S.Long. The Servo Span, or distance from the top servo reader to the bottom servo reader will then be:

[0288] 24

[0289] The next step is to determine the length of the servo band. Observing FIG. 22, thetop of the servo band is a distanceabove the center of S.Short positioned for the first Even Read Wrap. For the first Even Write Wrap, the write transducers are positioned so the topedge of the write transducer abuts the lower edge of the top Outer Buffer. The distancebetween the center of the write transducer and read transducer for the first Even Wrap is^^^^^^^^^^:

[0291] The write transducer then will write ^^^^ Wraps, stepping a distance ^^^ perWrap (see FIG.21). The distance moved, ^^^, is then:

[0293] The lower edge of the servo will abut the top of the lower servo band Guard,which isbelow the center of the servo. The servo band width, ^^^ , is given by the sum ofthe terms described above.

[0295] Combining Equations 25, 26 and 27a gives:

[0297] Substituting 10b into 27b (using ^^^^ for ^^^^^ from 12b) yields ^^^ in terms of^^^:

[0300] The final dimension needed is ^^^, which is solved using Equation 9 for ^^^^^ ,which contains the dimensions W^^(Equation 8) and W^^(Equation 20c):

[0301] ^^^ =

[0302] The optimum choice of Element (transducer) Pitch, ^^^, is then determinedusing the tape input values of tape Width ^^^^^ , Edge Guard Band width ^^^^^ , Number ofdata bands ^^^, and the head / drive parameter of the number of transducers (elements) ^^ andthe servo band guard ^^^^ and data band guard ^^^^ and the Outer and Inner Buffers^^^^^^^and ^^^^^^chosen for drive operation. To first order, ^^^is

[0304] which is the used portion of tape (^^^^^ − 2 ∙ ^^^^^ ) divided by the totalnumber of sub data bands (^^ ∙ ^^^).

[0305] Head Assembly / Alignment, 1-Band Head and Dual Servo Reader Option

[0306] A 1-Band Head is one where the elements span a single band, surrounded byservo bands. FIG. 24 is a schematic for a 1-Band Head with ^^ transducers utilizing a dualservo reader option for a 3-module head alignment with a Left Write transducer (LW) andRight Write transducer (RW) and Center Read transducer (CR). To match FIG. 24 alignmentwith FIGS.21-22, the picture is rotated 90 degrees clockwise. LW refers to media travelingfrom Left to Right in FIGS. 21-22, so LW will be writing and the CR will be reading EvenWraps. RW refers to media traveling from Right to Left in Figures 3 and 4 so LW will bewriting and the CR will be reading Odd Wraps. S servo readers, S1b and S2b will be used forEven Wraps and T servo readers, S1a and S2a, for Odd Wraps.

[0307] Head Assembly / Alignment, 2-Band Head and Dual Servo Reader Option

[0308] A 2-Band Head is one where the transducers span two bands, half the transducersare in one band and the other half are in an adjacent band, with 3 groups of servo readers in 3servo bands. For a 2-Band head, the media should have an even number of data bands withdata being written to or read from two adjacent data bands simultaneously. The arrangement during read or write is: SB, DB, SB, DB, SB.

[0309] FIG. 25 is a schematic for a 2-Band Head with N^ transducers in each Group (Aand B) utilizing a dual servo reader option for a 3-module head alignment with a Left Write transducer, (LW), a Right Write transducer, (RW), and Center Read transducer, (CR). Tomatch FIG. 25 alignment with FIGS. 21 and 22, the picture is rotated 90 degrees clockwise.LW refers to media traveling from Left to Right in FIGS.21 and 22 so LW will be writing and the CR will be reading Even Wraps (Forward or Fwd.). RW refers to media traveling from Right to Left in FIGS.21 and 22 so RW will be writing and the CR will be reading OddWraps (Reverse or Rev.). S servo readers, Snb, will be used for Even Wraps and T servoreaders, Sna, for Odd Wraps (or vice versa).

[0310] Because of the cost of wafer processing and redesigning a servo scheme for themedia, a general design is often reused for several generations. The head design of ElementPitch and servo reader locations may remain fixed and only parameters such as readtransducer and write transducer widths and track pitch are changed to achieve highercapacity. The media servo pattern locations and widths remain unchanged, only modifyingthe media properties such as magnetic layers, surface roughness, substrate thickness and length needed for higher capacity.

[0311] The change in the optimum Element Pitch is not affected by the writer width.

[0312]

[0313] The dependence on optimized ^^^ and a change in ^^^ is given by:

[0314] For ^^ = 64 and ^^^ changing from 500 to 200 nm, the change in the optimum^^^is only 4.7 nm. By using a design calculated for a fixed ^^^of 350 nm, the head will function for the full range with minor or no reduction in the capacity (^^^^) for a ^^^other than 350 nm.

[0316] The change in ^^^.^^^^ and ^^^.^^^^^ with changes in ^^^ are given here:^^

[0317] ^^.^^^^^^^^.^^^^^^^^^= ^^^^ = −0.5 32

[0318] A change in ^^^ from 500 to 200 nm will change the optimum ^^^.^^^^ and^^^.^^^^^by -150 nm each. By using a design calculated for a fixed ^^^of 350 nm, the head will function for the full range with minor or no reduction in the capacity (^^^^) for ^^^other than 350 nm. Since the design will be for a given media, the locations and sizes of the servo patterns remain unchanged resulting in only minor or no reduction in the capacity achieved compared to the optimum.

[0319] Head Design

[0320] Extant reader and writer tape modules for a magnetic head assembly aredeveloped by depositing material onto a ceramic substrate. The deposition is built upvertically. For a ringed write transducer, the first pole deposited is termed P1 and the latter deposited pole is P2. From the tape bearing surface, TBS, one sees the outline of P1, a Gap of non-magnetic material and P2. Figure 8 is a schematic for a 1-Band Head with N^transducerutilizing a dual servo reader option for a 3-module head alignment with a LW and RW andCR. The LW and RW respectively write while Media moving from Left-to-Right and Right-to-Left. (a) write transducer pole P2 is the trailing edge; (b) write transducer pole P1 is thetrailing edge. Because of processing constraints, the geometry of P1 and P2 are often different. The trailing pole material dominates the quality of the written magnetic bit transition. Because of differences in processing either P1 or P2 trailing could be preferrable. With the symmetric design described in this disclosure, one can use either P1 or P2 trailing without modifying the drive code. Because of the long time and large cost in building wafersand developing drive code, the versatility in enabling either P1 or P2 trailing designs with thesame wafer is highly beneficial in time, effort, and cost.

[0321] Media Reuse

[0322] Extant reader and writer magnetic tape heads are developed by depositingmaterial onto a ceramic substrate. The deposition is built up vertically. For a ringed writetransducer, the first pole deposited is termed P1 and the latter deposited pole is P2. From the tape bearing surface, TBS, one sees the outline of P1, a Gap of non-magnetic material and P2.

[0323] FIG. 26 is a schematic for a 1-Band Head with N^ transducers utilizing a dualservo reader option for a 3-module head alignment with a LW, RW, and CR. The LW andRW respectively write while media moves from Left-to-Right and Right-to-Left. Part (a) ofFIG. 26 depicts a write transducer pole P2 is the trailing edge; Part (b) depicts writetransducer pole P1 is the trailing edge. Because of processing constraints, the geometry of P1and P2 are often different. The trailing pole material dominates the quality of the written magnetic bit transition. Because of differences in processing either P1 or P2 trailing could be preferrable. With the symmetric design described in this disclosure, one can use either P1 or P2 trailing without modifying the drive code. Because of the long time and large cost in building wafers and developing drive code, the versatility in enabling either P1 or P2 trailingdesigns with the same wafer is highly beneficial in time, effort, and cost.

[0324] Tilted Head for Tape Dimensional Stability Compensation

[0325] In writing data to tape with a multi-transducer Read / Write head, the effectivespacing between transducers can increase or decrease due to changes in spacing on the headand / or in the media. Expansion or contraction of the head and / or media width due to thermaleffects, humidity or other stresses can occur. One methodology of correcting for thesechanges is to tilt the head at an angle relative to the track direction according to knownmethods. For example, if the media moves in the x direction and the track pitch is in the y direction, rotating the head by an angle q relative to the y axis will shorten the effective trackpitch in the frame of the tape. The head can be built with a fixed value of ^^ and activecompensation of the angle about the center can be done. The analysis given so far can be generalized to include the head tilt concept by analyzing the dimensions in the reference ofthe media. Thus, the media dimensions, ^^^^^^ , are fixed and the head dimensions, ^^^^^, aretranslated to the media reference plane by multiplying by cos (^^). The calculations for thehead dimensions, are then done in the reference plane of the media and then translated back tothe head reference frame by multiplying by 1 / cos (^^).

[0326] Media parameters include:

[00327] Head parameters include: ^^ , ^^ , ^^ , ^^^ ^^^.

[0328] FIG. 27 shows the concept of tilting pictorially, e.g., for tape dimensionalstability (TDS) compensation, whereby said concept may be applied to various aspects of the present invention, as would become apparent to one skilled in the art after reading the present disclosure. The Pisa angle is the nominal angle q of tilt.

[0329] Media Reuse Examples

[0330] An example of media reuse includes using media designed for a given set of headparameters with a new head design having parameters designed for a higher capacity, but which can fit within the original media design, but will overwrite a portion of the pre-written servo pattern. With a fixed media width, ^^^^^, and edge guard band, ^^^^^, and track pitch,^^^, and write transducer width ^^ and Buffers, Equation 12d shows that the means ofincreasing the capacity (i.e. ^^^^) is by increasing the Element (transducer) Pitch ^^^ . Herean evaluation of different options is explored.

[0331] Table 1 gives general Media and Head parameters common to the three designsevaluated. Table 2 gives an evaluation of four head designs and operating points using theEquations described above. Design D1 is a legacy design using 1 servo reader per servo band,33 transducers and 32 data channels which is not optimized for capacity. Designs D2 and D3use 1 servo reader per servo band and have 33 and 32 transducers respectively and areoptimized for capacity. Design D4 uses 2 servo readers per servo band and uses 32transducers and 32 channels and is optimized for capacity. Designs D2, D3 and D4 can usethe media for designs D1 by overwriting the servo band Pattern with respective gains incapacity of 4.1, 4.1 and 6.8%. Design D4 can also use the media from Designs D2 and D3 byoverwriting a portion of their servo bands with a gain in capacity of 2.7%. To make thedesigns compatible, the Edge guard band, ^^^^^, was fixed.

[0332] Designs D5 to D7 are for a 1-Band Head using three (3) data bands. Designs D5and D6 are designed to use the same Head structure containing 65 transducers and 2 servo readers. Design D5 is a 64 Channel head with half the Element Pitch or the 32 Chanel head design, D6. Design D6 is optimized for capacity and the Element pitch for Design D5 is half that of Design D6. Designs D5 and D6 use the same head and media structure but requireseparate servo readers to operate. Design D7 thus is not fully optimized for capacity and doesnot use the available servo band width from D6 but does use the same media as Design D6.This allows for using the same Head and Media for a 32 and a 64 Channel operation. Thedramatic drop in capacity for Design D6 compared to D7 (-8.2%) is primarily due to the factthat ^^^^~(^^^ − ^^ ) / ^^^. Since ^^ is 17% of ^^^.^^ and only 8.7% of ^^^.^^, thewrite transducer width reduces the capacity more for the 64-channel design than for the 32-channel design for the 1-band design. Design D7 uses 2 Servos per servo band, also with a 3-Band Media design. Design D7 can reuse media from the D6 design with a gain in capacity of 3.1%. Table 1. General Media and Head parameters common to the designs ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^# mm mm mm mm mm mm mm mm4 12,650 558.5 2.0 10.0 4 0.25 0.25 0.5Table 2. Comparison of design for variations in number of servo readers per band and^^. Capacity gain is relative to the lowest capacity option evaluated (1 servo per servo band, SB) (1) and highest number of transducers (33), which has the lowest ^^^. General parameters are given in Table 1. Desig ^^^^Servo ^^^^^^^^^^^^^^^^^^^^^.^^^^^^^.^Capacit Capaci n reade y ty rper^^^Gain SB∙ ^^ ∙ ^^^^# mm # # # mm # mm mm mm # %D1* 46. 1 4 33 32 83.25 146 93.00 97.5 18688 0.0%5 D2 0 1 4 33 32 86.33 152 88.58 47.79 19456 4.1%D3 0 1 4 32 32 86.37 152 87.62 90.99 19456 4.1%D4 0 2 4 32 32 88.02 156 45.26 92.90 48.6 19968 6.8%4 D5 0 1 3 65 64 58.63 96 60.88 33.94 18432 -1.4%D6 0 1 3 32 32 114.96 208 116.2 119.59 19968 6.8%1 D7 0 2 3 32 32 117.31 214 59.90 122.18 63.2 20544 9.9%8 D8 0 1 1 65 64 174.43 328 176.6 91.84 20992 12.3%8 * Design D1 is a legacy design which is not optimized for capacity, ^^^^=49 mm.

[0333] A further example of magnetic tape media reuse includes using a first magnetictape media designed for a tape drive having a first set of magnetic head parameters with a new magnetic head design having a second set of magnetic head parameters designed for a higher capacity. Wherein the new magnetic head is also called a second magnetic head having a second set of magnetic head parameters, the second magnetic head is part of a second tape drive. The second magnetic head is described by the figures and paragraphs of thisapplication. The writing with the second magnetic head on the first magnetic tape media isdescribed by the figures and paragraphs of this application.

[0334] The first tape media which is designed for a first magnetic head of a first tapedrive can fit into a second tape drive having a second magnetic head. Wherein the first and the second magnetic heads have different sets of magnetic head parameters.

[0335] The first magnetic tape media can fit within the original media design. The usageof the first magnetic tape media in a second tape drive will overwrite a portion of the pre- written servo pattern of the first magnetic tape. With a fixed media width, ^^^^^, and edge guard band, ^^^^^, and track pitch, ^^^, and write transducer width ^^and Buffers,Equation 12d shows that the means of increasing the capacity (i.e. ^^^^) is by increasing theElement (transducer) Pitch ^^^. The evaluation of different options is explored in the tables above.

[0336] Clauses

[0337] 1. Clause: A method, comprising: writing, by a second tape drive, data tracks to adata band of a first magnetic tape having servo bands flanking the data band, wherein the first magnetic tape is designed for usage in a first tape drive having a first set of magnetic head parameters, the writing being performed using a second magnetic head, wherein the second magnetic head is designed for usage in a second tape drive having a second set of magnetic head parameters, wherein the writing by the second tape drive includes overwriting a portion of each of the servo bands with the data tracks of the first magnetic tape.

[0338] 2. Clause: A method as recited in clause 1, wherein the second magnetic head hasat least two servo readers positioned on one side of an array of magnetic write transducers and at least two servo readers positioned on an opposite side of the array of magnetic write transducers, wherein the second tape drive is configured to use a first one of the servo readers positioned on each side of the array for writing data tracks in a first portion of the data band of the first magnetic tape and to use a second one of the servo readers positioned on each side of the array for writing data tracks in a second portion of the data band of the first magnetic tape.

[0339] 3. Clause: A method as recited in clause 1 or 2, wherein centerlines of theportions of the servo bands used during the writing are original centerlines of the servo bands.

[0340] 4. Clause: A method as recited in clause 3, wherein an effective pitch of servoreaders of the second magnetic head used simultaneously during the writing matches a servo reader pitch specification of the format of the first magnetic tape, wherein an average effective pitch of write transducers of the second magnetic head is greater than a data track pitch specification of the format of the first magnetic tape.

[0341] 5. Clause: A method as recited in any one of the claims 1 to 3, wherein aneffective pitch of servo readers of the second magnetic head used simultaneously during the writing matches a servo reader pitch specification of the format of the first magnetic tape, wherein an average effective pitch of write transducers of the second magnetic head is greater than a data track pitch specification of the format of the first magnetic tape.

[0342] 6. Clause: A method as recited in the clause 1 or 2, wherein centerlines of theportions of the servo bands used during the writing are offset from original centerlines of the servo bands.

[0343] 7. Clause: A method as recited in any one of the clauses 1 to 6, wherein aneffective pitch of servo readers of the second magnetic head used simultaneously during the writing is less than a servo reader pitch specification of the format of the first magnetic tape, wherein an average effective pitch of write transducers of the second magnetic head is greater than a data track pitch specification of the format of the first magnetic tape.

[0344] 8. Clause: A method as recited in any one of the clauses 1 to 7, wherein one ofthe servo bands is completely overwritten with data tracks during the writing.

[0345] 9. Clause: A method as recited in clause 8, wherein an effective pitch of servoreaders of the second magnetic head used simultaneously during the writing is greater than a width of two data bands on the first magnetic tape.

[0346] 10. Clause: A method as recited in clause 8, wherein the second magnetic headhas at least two servo readers positioned on one side of an array of magnetic write transducers and at least two servo readers positioned on an opposite side of the array of magnetic write transducers, wherein the second tape drive is configured to use a first one of the servo readers positioned on each side of the array for writing a first set of the data tracks and to use a second one of the servo readers positioned on each side of the array for writing a second set of data tracks.

[0347] 11. Clause: An apparatus, comprising: a drive mechanism for passing a firstmagnetic tape over a second magnetic head, wherein the first magnetic tape is designed for usage in a first tape drive having a first set of head parameters, and wherein the second magnetic head is designed for usage in a second tape drive having a second set of head parameters; and a controller electrically coupled to the second magnetic head, the controller being configured for performing a method according to any one of the clauses 1 to 10.

[0348] Clause 12: A computer program product for enabling use of a first magnetic tapeby a second tape drive, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructionsfor executing by the second tape drive for performing a method according any of the clauses 1 to 10.

[0349] It will be clear that the various features of the foregoing systems and / ormethodologies may be combined in any way, creating a plurality of combinations from the descriptions presented above.

[0350] It will be further appreciated that aspects of the present invention may beprovided in the form of a service deployed on behalf of a customer to offer service on demand.

[0351] The descriptions of the various aspects of the present invention have beenpresented for purposes of illustration but are not intended to be exhaustive or limited to theapproaches disclosed. Many modifications and variations will be apparent to those of ordinaryskill in the art without departing from the scope and spirit of the described approaches. The terminology used herein was chosen to best explain the principles of the present invention, the practical application or technical improvement over technologies found in the marketplace, orto enable others of ordinary skill in the art to understand the approaches disclosed herein.

Claims

CLAIMS1. A method, comprising:writing, by a tape drive, data tracks to a data band of a magnetic tape having servo bandsflanking the data band, the writing being performed using a magnetic head that is notdesigned for a format of the magnetic tape,wherein the writing includes overwriting a portion of each of the servo bands with the datatracks.

2. A method as recited in claim 1, wherein the magnetic head has at least two servoreaders positioned on one side of an array of magnetic write transducers and at least two servo readers positioned on an opposite side of the array of magnetic write transducers, wherein the tape drive is configured to use a first one of the servo readers positioned on each side of the array for writing data tracks in a first portion of the data band and to use a second one of the servo readers positioned on each side of the array for writing data tracks in a second portion of the data band.

3. A method as recited in claims 1 or 2, wherein centerlines of the portions of the servobands used during the writing are original centerlines of the servo bands.

4. A method as recited in claim 3, wherein an effective pitch of servo readers of themagnetic head used simultaneously during the writing matches a servo reader pitchspecification of the format of the magnetic tape, wherein an average effective pitch of writetransducers of the magnetic head is greater than a data track pitch specification of the formatof the magnetic tape.

5. A method as recited in any one of the claims 1 to 3, wherein an effective pitch ofservo readers of the magnetic head used simultaneously during the writing matches a servoreader pitch specification of the format of the magnetic tape, wherein an average effective pitch of write transducers of the magnetic head is greater than a data track pitch specification of the format of the magnetic tape.

6. A method as recited in any one of the claims 1, 2, 4, 5, wherein centerlines of theportions of the servo bands used during the writing are offset from original centerlines of the servo bands.

7. A method as recited in any one of the claims 1, 2, 3, 6, wherein an effective pitch ofservo readers of the magnetic head used simultaneously during the writing is less than a servoreader pitch specification of the format of the magnetic tape, wherein an average effectivepitch of write transducers of the magnetic head is greater than a data track pitch specificationof the format of the magnetic tape.

8. A method as recited in any one of the claims 1 to 7, wherein one of the servo bands iscompletely overwritten with data tracks during the writing.

9. A method as recited in claim 8, wherein an effective pitch of servo readers of themagnetic head used simultaneously during the writing is greater than a width of two data bands on the magnetic tape.

10. A method as recited in claim 8, wherein the magnetic head has at least two servoreaders positioned on one side of an array of magnetic write transducers and at least two servo readers positioned on an opposite side of the array of magnetic write transducers, wherein the tape drive is configured to use a first one of the servo readers positioned on each side of the array for writing a first set of the data tracks and to use a second one of the servoreaders positioned on each side of the array for writing a second set of data tracks.

11. An apparatus, comprising:a drive mechanism for passing a magnetic tape over a magnetic head; anda controller electrically coupled to the magnetic head, the controller being configured to:cause the magnetic head to write data tracks to a data band of the magnetic tape,the magnetic tape having servo bands flanking the data band,wherein the magnetic head is not designed for a format of the magnetic tape,wherein the writing includes overwriting a portion of each of the servo bands with the data tracks.

12. An apparatus as recited in claim 11, wherein the magnetic head has at least two servoreaders positioned on one side of an array of magnetic write transducers and at least two servo readers positioned on an opposite side of the array of magnetic write transducers,wherein the apparatus is configured to use a first one of the servo readers positioned on eachside of the array for writing data tracks in a first portion of the data band and to use a second one of the servo readers positioned on each side of the array for writing data tracks in a second portion of the data band.

13. An apparatus as recited in claims 11 or 12, wherein centerlines of the portions of theservo bands used during the writing are original centerlines of the servo bands.

14. An apparatus as recited in claim 13, wherein an effective pitch of servo readers of themagnetic head used simultaneously during the writing matches a servo reader pitchspecification of the format of the magnetic tape, wherein an average effective pitch of writetransducers of the magnetic head is greater than a data track pitch specification of the formatof the magnetic tape.

15. An apparatus as recited in any one of the claims 11 to 13, wherein an effective pitchof servo readers of the magnetic head used simultaneously during the writing matches a servoreader pitch specification of the format of the magnetic tape, wherein an average effective pitch of write transducers of the magnetic head is greater than a data track pitch specification of the format of the magnetic tape.

16. An apparatus as recited in any one of the claims 11 or 12, wherein centerlines of theportions of the servo bands used during the writing are offset from original centerlines of the servo bands.

17. An apparatus as recited in any one of the claims 11, 12, 13, 16, wherein an effectivepitch of servo readers of the magnetic head used simultaneously during the writing is less than a servo reader pitch specification of the format of the magnetic tape, wherein an averageeffective pitch of write transducers of the magnetic head is greater than a data track pitchspecification of the format of the magnetic tape.

18. An apparatus as recited in any one of the claims 11 to 17, wherein one of the servobands is completely overwritten with data tracks during the writing.

19. An apparatus as recited in claim 18, wherein an effective pitch of servo readers of themagnetic head used simultaneously during the writing is greater than a width of two of the data bands on the magnetic tape.

20. An apparatus as recited in claim 18, wherein the magnetic head has at least two servoreaders positioned on one side of an array of magnetic write transducers and at least two servo readers positioned on an opposite side of the array of magnetic write transducers, wherein the apparatus is configured to use a first one of the servo readers positioned on each side of the array for writing a first set of the data tracks and to use a second one of the servo readers positioned on each side of the array for writing a second set of data tracks.

21. A computer program product for enabling use of a magnetic tape by a tape drive notdesigned for a format of the magnetic tape, the computer program product comprising acomputer readable storage medium having program instructions embodied therewith, the program instructions executable by the tape drive to cause the tape drive to:write, by the tape drive, data tracks to a data band of the magnetic tape having servo bandsflanking the data band, the writing being performed using a magnetic head that is not designed for a format of the magnetic tape, wherein the writing includes overwriting a portion of each of the servo bands with the data tracks.

22. A computer program product as recited in claim 21, wherein centerlines of theportions of the servo bands used during the writing are original centerlines of the servo bands.

23. A computer program product as recited in claim 21, wherein centerlines of theportions of the servo bands used during the writing are offset from original centerlines of the servo bands.

24. A method, comprising:writing, by a tape drive, data tracks to a data band of a magnetic tape having servo bands flanking the data band, the writing being performed using a magnetic head that is not designed for a format of the magnetic tape,wherein an effective pitch of servo readers of the magnetic head used simultaneously duringthe writing matches a servo reader pitch specification of the format of the magnetic tape,wherein an average effective pitch of write transducers of the magnetic head is greater than a data track pitch specification of the format of the magnetic tape, wherein the writing includes overwriting a portion of each of the servo bands with the data tracks.

25. A method as recited in claim 24, wherein the magnetic head has at least two of theservo readers positioned on one side of an array of magnetic write transducers and at least two of the servo readers positioned on an opposite side of the array of magnetic write transducers, wherein the tape drive is configured to use a first one of the servo readers positioned on each side of the array for writing data tracks in a first portion of the data bandand to use a second one of the servo readers positioned on each side of the array for writingdata tracks in a second portion of the data band.

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