Constant density writing for magnetic storage media

Abstract

This disclosure describes aspects for constant density writing for magnetic storage media. In some aspects, a constant density writer delays transitions between bits within write data to achieve constant density writing. The write data has an initial bit period that is based on a constant clock signal that is generated based on rotation of a media disk. The constant density writer modifies the write data to generate phase-delayed write data that has a bit period that is greater than or equal to the initial bit period. To achieve this bit period, the constant density writer changes a write phase of bit transitions within the write data. The constant density writer can also insert stretch bits, filter unit transitions, and mitigate glitches within the phase-delayed write data.

Description

[0001] Case Analysis

[0002] This application is a divisional application of Chinese invention patent application No. 202080020304.8, filed on March 10, 2020, entitled "Constant Density Writing for Magnetic Storage Media".

[0003] Cross-reference to related applications

[0004] This disclosure claims priority to U.S. Provisional Patent Application Serial No. 62 / 816,760, filed March 11, 2019, the disclosure of which is incorporated herein by reference in its entirety. Background Technology

[0005] Electronic devices provide numerous services to modern society. These services enable electronic devices to offer entertainment, assist in scientific research and development, and provide many modern conveniences. Many of these services create or utilize the data stored on electronic devices. This data can include digital media such as books or movies, algorithms that perform complex simulations, personal user data, applications, and more. To avoid exceeding data storage limits, it is beneficial to increase the data storage capacity of electronic devices and avoid deleting data, limiting services, or purchasing additional external storage devices.

[0006] Many electronic devices use media drives to store data on disks, such as hard disk drives. Typically, the data on each disk is organized along concentric tracks of magnetic medium, where individual bits of data are written. To accommodate larger amounts of user data, the data density of each media disk has increased dramatically, thereby reducing the physical geometry of both the tracks and bits written on the magnetic medium. To accommodate even larger amounts of user data, it is beneficial to make efficient use of the media disk's area. Summary of the Invention

[0007] This "Summary" is provided to introduce the subject matter further described in the "Detailed Description" and "Drawings". Therefore, this "Summary" should not be used to limit the scope of the claimed subject matter.

[0008] This disclosure describes an apparatus and technique for constant-density writing of magnetic storage media for delayed transitions between bits within a delayed data stream. Specifically, the constant-density writer accepts write data having an initial bit period based on a fixed clock signal. The clock signal is generated based on the rotation of the media disk. The constant-density writer modifies the write data to generate phase-delayed write data, the bit period of which is greater than or equal to the initial bit period. To achieve the bit period, the constant-density writer alters the write phase of bit transitions within the write data. The constant-density writer can also insert stretched bits, filter single-bit transitions, and mitigate glitch within the phase-delayed write data.

[0009] In some respects, a constant-density writer for magnetic storage media implements a method for accepting write data from a host. The constant-density writer determines the corresponding bit period of a concentric track among multiple concentric tracks of the magnetic storage medium's disk. Each bit period is associated with a specific concentric track. The corresponding bit period varies based on the corresponding radius of the multiple concentric tracks and is configured to maintain a specific bit density across the multiple concentric tracks. The constant-density writer selects a concentric track from the multiple concentric tracks for the write data. The constant-density writer delays the transitions between bits of the write data based on the bit period associated with the concentric track to generate phase-delayed write data. In this way, the bits of the phase-delayed write data have a bit period associated with the concentric track. The bits of the phase-delayed write data are written along the concentric tracks such that the concentric tracks have a specific bit density.

[0010] In other aspects, an apparatus includes an interface for receiving write data from a host, a disk for storing the write data in a magnetic storage medium, a magnetic medium writer configured to write the write data as data bits to the magnetic storage medium, and a constant density writer. The constant density writer is configured to determine a corresponding bit period of a plurality of concentric tracks. Each bit period is associated with a specific concentric track. The corresponding bit period varies based on a corresponding radius of the plurality of concentric tracks and is configured to maintain a specific bit density across the plurality of concentric tracks. The constant density writer is also configured to select a concentric track from the plurality of concentric tracks for the write data. The concentric track is associated with a bit period in the corresponding bit period. To generate phase-delayed write data, the constant density writer delays the transition between bits of the write data based on the bit period of the concentric track to effectively cause the bits of the phase-delayed write data to have a bit period associated with the concentric track. The constant density writer is also configured to transmit the phase-delayed write data to the magnetic medium writer such that the concentric tracks can have a specific bit density.

[0011] In other aspects, a system-on-chip (SoC) is described, comprising an interface to a host from which write data is received, an interface to a magnetic medium writer of magnetic storage medium, and a constant-density writer at least partially implemented in hardware. The constant-density writer is configured to determine a corresponding bit period of a plurality of concentric tracks. Each bit period is associated with a specific concentric track. The corresponding bit period varies based on a corresponding radius of the plurality of concentric tracks and is configured to maintain a specific bit density across the plurality of concentric tracks. The constant-density writer is also configured to select a concentric track from the plurality of concentric tracks for write data. The concentric track is associated with a bit period in the corresponding bit period. To generate phase-delayed write data, the constant-density writer delays the transition between bits of the write data based on the bit period of the concentric track to effectively cause the bits of the phase-delayed write data to have a bit period associated with the concentric track. The constant-density writer is also configured to transmit the phase-delayed write data to the magnetic medium writer such that the concentric tracks can have a specific bit density.

[0012] Details of one or more implementations are set forth in the accompanying drawings and the following description. Other features and advantages will be apparent from the specification, the drawings, and the claims. Attached Figure Description

[0013] Details of one or more implementations of constant-density writing for magnetic storage media are illustrated in the accompanying drawings and the following detailed description. In the drawings, the leftmost numeral indicates the figure in which the numeral first appears. The use of the same numerals in different instances in the specification and drawings indicates the same elements:

[0014] Figure 1 An example operating environment is shown, according to one or more implementations, having a device in which a magnetic storage medium is implemented.

[0015] Figure 2 It shows Figure 1 The example configuration of the hard drive shown is shown.

[0016] Figure 3 An example configuration for the read / write channel is shown.

[0017] Figure 4 It shows Figure 3 Example diagrams of written data and phase-delayed written data.

[0018] Figure 5 It shows Figure 1 An example implementation of a constant density writer.

[0019] Figure 6 It shows the result of Figure 5 Example image of data generated by a constant density writer.

[0020] Figure 7 Depicting the use of Figure 5 An example method for implementing constant-density writing to magnetic storage media using a constant-density writer.

[0021] Figure 8 The following diagram illustrates the implementation. Figure 2 Examples of system-on-chip (SoC) environments with constant density writing of magnetic storage media.

[0022] Figure 9 It shows the configuration associated with the controller. Figure 2 An example storage medium controller for achieving constant density writing in magnetic media. Detailed Implementation

[0023] To accommodate larger amounts of user data, it is beneficial to make efficient use of the disk media area. For example, as described in this disclosure, constant density writing allows the disk media to have similar bit densities across different concentric tracks with different radii. Instead of writing data at a single frequency, data can be written at a higher frequency along concentric tracks positioned towards the outside of the disk media, relative to data written along other concentric tracks positioned towards the center of the disk media. In this way, constant density writing effectively utilizes the disk media area and allows additional data to be written to the disk media.

[0024] However, some conventional media drives generate write patterns based on a fixed clock frequency determined by the rotation of the media disk. In some media drives, the clock frequency can be adjusted relative to the rotation of the media disk. However, these adjustments may be relatively large and insufficient to achieve constant density writes. Therefore, the media drive generates multiple regions with different bit densities across the media disk, which is less efficient than constant density writes.

[0025] This disclosure describes an apparatus and technique for constant-density writing to magnetic storage media. Instead of adjusting the clock frequency relative to the rotation of the media disk, the described apparatus and technique achieve constant-density writing by delaying the transitions between bits within a data stream. Specifically, the constant-density writer accepts write data with an initial bit period based on a fixed clock signal. The clock signal is generated based on the rotation of the media disk. The constant-density writer modifies the write data to generate phase-delayed write data, the bit period of which is greater than or equal to the initial bit period. To achieve the bit period, the constant-density writer alters the write phase of the bit transitions within the write data. The constant-density writer can also insert stretched bits, filter unit transitions, and mitigate faults within the phase-delayed write data.

[0026] The following discussion describes the operating environment, the technologies employed in that operating environment, and the system-on-a-chip (SoC) in which the components embody that operating environment. In the context of this disclosure, the operating environment is referred to by way of example only.

[0027] Operating environment

[0028] Figure 1 An example operating environment 100 is shown, which has a computing device 102 capable of storing or accessing data or information in various forms. Examples of computing devices 102 include laptop computers 104, desktop computers 106, and servers 108, any of which can be configured as part of a storage network or cloud storage. Other examples of computing devices 102 (not shown) include tablet computers, set-top boxes, data storage devices, wearable smart devices, televisions, content streaming devices, high-definition multimedia interface (HDMI) media sticks, smart home appliances, home automation controllers, smart thermostats, Internet of Things (IoT) devices, mobile internet devices (MIDs), network-attached storage (NAS) drives, aggregated storage systems, game consoles, car entertainment systems, car computing systems, car control modules (e.g., engine or powertrain control modules), etc.

[0029] Typically, computing device 102 provides, transmits, or stores data for any suitable purpose, such as enabling the functionality of a particular type of device, providing a user interface, enabling network access, implementing game applications, playing media, providing navigation, editing content, providing data storage, etc. Alternatively or additionally, computing device 102 can store various types of data, such as databases, user data, multimedia, applications, operating systems, etc. One or more computing devices 102 can be configured to provide remote data storage or services, such as cloud storage, archiving, backup, client services, record retention, etc.

[0030] Computing device 102 includes a processor 110 and a computer-readable storage medium 112. The processor 110 is implemented as any suitable type or number of processors (single-core or multi-core, e.g., ARM or x86 processor cores) for executing instructions or commands of an operating system or other programs of computing device 102. The computer-readable storage medium 112 (CRM 112) includes a memory medium 114 and a media drive 116. The memory medium or system memory of computing device 102 includes any suitable type or combination of volatile or non-volatile memory. For example, the volatile memory of computing device 102 includes various types of random access memory (RAM), dynamic RAM (DRAM), static RAM (SRAM), etc. Non-volatile memory may include read-only memory (ROM), electrically erasable programmable ROM (EEPROM), or flash memory (e.g., NOR flash or NAND flash). These memories, individually or in combination, store data associated with applications and / or the operating system of computing device 102.

[0031] The media drive 116 of computing device 102 includes one or more media drives, or is implemented as part of a data storage system associated with computing device 102. In this example, media drive 116 includes a hard disk drive 118 (HDD 118), which is capable of storing data and is described with reference to aspects of constant density writes. Alternatively or additionally, media drive 116 may be configured as any suitable type of data storage drive or system, such as a storage device, storage drive, storage array, storage volume, etc. Although described with reference to computing device 102, media drive 116 may also be implemented independently as a standalone device or as part of a larger storage assembly, such as a data center, server cluster, or virtualized storage system (e.g., for cloud-based storage or services), where aspects of constant density writes are implemented.

[0032] In the depicted configuration, computing device 102 also includes I / O port 120, a graphics processing unit (GPU, not shown), and data interface 122. Typically, I / O port 120 allows computing device 102 to interact with other devices, peripherals, or the user. For example, I / O port 120 may include or be coupled to a universal serial bus, human-machine interface device, audio input, audio output, etc. The GPU processes and renders graphics-related data of computing device 102, such as user interface elements of the operating system, applications, etc. In some cases, the GPU accesses a portion of local memory to render graphics, or includes dedicated memory (e.g., video RAM) for rendering graphics of computing device 102.

[0033] The data interface 122 of computing device 102 provides connectivity to one or more networks and other devices connected to those networks. Data interface 122 may include a wired interface, such as an Ethernet or fiber optic interface, for transmitting data over a local network, intranet, or the Internet. Alternatively or additionally, data interface 122 may include a wireless interface supporting communication over wireless networks, such as wireless LANs, wide area wireless networks (e.g., cellular networks), and / or wireless personal area networks (WPANs). Any data transmitted through I / O port 120 or data interface 122 may be written to or read from the storage system of computing device 102, depending on one or more aspects of constant density writing to the magnetic storage medium.

[0034] Returning to media drive 116, computing device 102 includes hard disk drive 118 as shown and / or other types of storage media on which constant density writing is implemented. Although not shown, other configurations of media drive 116 are also contemplated, such as tape drives, optical media drives, HDD / SSD hybrid drives, and other storage systems that write data to storage media (e.g., magnetic or optical storage media). Alternatively or additionally, computing device 102 may include a media drive array, or a media drive aggregation device or host that serves as multiple media drives for aspects of constant density writing implemented therein.

[0035] In this example, the disk drive 118 includes a head disk assembly 124 (HDA 124) and a drive control module 126 to implement or enable the functionality of the hard disk drive 118, which may include self-servo writing. In some cases, the drive control module 126 is implemented as a printed circuit board assembly (PCBA) having semiconductor devices, logic, or other circuitry. The HDA 124 includes one or more media disks 128 mounted on an integrated spindle and motor assembly 130. The spindle and motor assembly 130 rotates the media disks 128 below (or above) read / write heads 132 coupled to the head assembly (not shown) of the HDA 124. The media disks 128 may be coated with a hard magnetic material (e.g., a granular surface or a thin film surface) and may be written to or read from one or both sides.

[0036] The read / write head 132 is operatively coupled to a preamplifier / writer module 134 (preamplifier / writer 134) of an HDA 124, which includes preamplifier circuitry. The preamplifier / writer 134 receives or stores head selection, amplification, or sensing current values ​​useful for writing data to or reading data from the magnetic medium 202.

[0037] like Figure 1As shown, the example drive control module 126 of the hard disk drive 118 includes a storage media controller 136, a servo control unit 138, and a read / write channel 140 (R / W channel 140). In some aspects, the read / write channel 140 includes a constant density writer 142, which is used to generate, manage, or modify various signals or data to achieve the characteristic of constant density writing to the magnetic storage medium. The constant density writer 142 will refer to... Figure 3-6 Further description. Typically, the drive control module 126 directs or uses the servo control unit 138 to control mechanical operations, such as positioning the read / write head 132 via the HDA 124 and controlling the rotational speed via the spindle and motor assembly 130. The drive control module 126 or its components may be implemented as one or more IC chips, system-on-a-chip, system-in-package, or a microprocessor equipped with or implementing a hard disk drive controller. The drive control module 126 may also include drive electronics (not shown) and / or include various interfaces, such as a host bus interface, storage media interface, spindle interface, or preamplifier / writer interface.

[0038] As an example, consider Figure 2 , Figure 2 A sample configuration of hard drive 118 is provided, which is generally shown as 200. (See example...) Figure 2 As shown, the HDA 124 of the hard disk drive 118 includes an integrated spindle and motor assembly 130, and the media disk 128 of the magnetic medium 202 is supported and / or operated by the spindle and motor assembly 130. The arm 204 can manipulate the read / write heads 132 (or multiple read / write heads 132) and thus position them over the desired tracks 206 of the magnetic medium 202 on the media disk 128. In various aspects, the read / write heads 132 include a variety of numbers of head elements having combined or separate functions (e.g., dedicated R / W functions). For example, the read / write head 132 includes one or more readers (read heads / elements) and one writer (write head / element). In other cases, the read / write head 132 includes a dedicated write head (element) and one or more separate additional dedicated read heads (elements). Alternatively or additionally, although... Figure 2 Multiple arms 204 are shown, but the HDA 124 or spindle and motor assembly 130 can be implemented with a single arm 204 or other suitable structures for positioning the read / write head 132. The HDA 124 and drive control module 126 can be implemented separately, on separate substrates, and / or as separate PCBAs for media drivers. Signals or data transmitted between the HDA 124 and drive control module 126 can be transmitted via flexible printed cables or other suitable connection structures such as traces, connectors, bonding wires, solder balls, etc.

[0039] Figure 2 The illustration also includes an example magnet 208 of the magnetic medium 202 written to the media disk 128. One or more of the read / write heads 132 write the magnet 208 to corresponding tracks in the tracks 206 of the media disk 128, wherein sectors (e.g., sectors of track 206) are provided for each track. For illustrative purposes, the top media disk 128 is shown as including the track 206, for example, after being written to by the read / write heads 132 with the magnet 208. Typically, during a write operation, the read / write heads 132 are driven by a write current provided by a preamplifier / writer 134, thereby using electrical signals to generate and / or deliver a magnetic field of associated polarity to the media disk 128. In response to the application of the magnetic field or write field, the read / write heads 132 form a plurality of magnets 208 in the magnetic particles of the tracks 206 of the media disk 128. The HDA 124 of the hard disk drive 118 is configured to perform write operations according to any suitable recording technology, such as perpendicular magnetic recording (PMR), shingled magnetic recording (SMR), heat-assisted magnetic recording (HAMR), microwave-assisted magnetic recording (MAMR), etc.

[0040] As shown in 210, the magnetic medium 202 includes a first concentric magnetic track 206-1 and a second concentric magnetic track 206-2. The first concentric magnetic track 206-1 is located near the interior of the magnetic medium 202, while the second concentric magnetic track 206-2 is located near the exterior of the magnetic medium 202. Therefore, the first concentric magnetic track 206-1 has a smaller radius and circumference relative to the second concentric magnetic track 206-2. When the magnetic medium 202 rotates, the first concentric magnetic track 206-1 has a linear velocity 214-1, which is smaller than the linear velocity 214-2 of the second concentric magnetic track 206-2 due to the different radii. In order to achieve constant density across the magnetic medium 202, the constant density writer 142 generates phase-delayed write data with different bit periods (e.g., different magnet periods or different magnetic write periods) for the different concentric magnetic tracks 206. The difference in bit period causes the preamplifier / writer 134 to write across the first concentric track 206-1 at a first write frequency 216-1 and across the second concentric track 206-2 at a second write frequency 216-2. The second write frequency 216-2 is higher than the first write frequency 216-1 to compensate for the difference in linear velocities 214-1 and 214-2. By using an appropriate write frequency 216, the preamplifier / writer 134 writes magnets with approximately the same effective bit period 212 along the first and second concentric tracks 206-1 and 206-2. In this way, the constant density writer 142 enables data bits to have a constant density across the media disk 128 in order to efficiently utilize the area of ​​the media disk 128.

[0041] Figure 3An example configuration of a read / write channel 140 is shown, implemented according to one or more aspects of constant density writing for a magnetic storage medium. In this example, a constant density writer 142 is operatively coupled to the read / write channel 140.

[0042] In this example, host interface 302 provides write data 304 or other information to read / write channel 140 or a storage media controller on which read / write channel 140 is embodied. Typically, read / write channel 140 provides phase-delayed write data 306 to preamplifier 134 of the media driver. Phase-delayed write data 306 may include signals corresponding to a data pattern intended for writing on the media. In aspects of constant density writing, constant density writer 142 modifies the phase-delayed write data 306 sent to preamplifier 134, such as by adjusting bit period based on selected concentric tracks 206, inserting stretched bits, filtering unit transitions, or any combination of similar operations. Constant density writer 142 may also generate or cause read / write channel 140 to generate control signals 308 for preamplifier 134 to enable or disable operation of preamplifier 134.

[0043] Typically, preamplifier 134 or preamplifier circuitry 310 generates or supplies write current to write head 132 of media driver 116. This write current has a polarity or switching pattern corresponding to the phase-delayed write data 306 (modified or unmodified) and / or the control signal 308 used for constant-density writing. Based on the data and / or control signal pattern provided by read / write channel 140 and constant-density writer 142, preamplifier 134 generates pulses or changes the polarity of the write current sent to write head 132.

[0044] A write current 312 generated by preamplifier 134 is provided to the corresponding write head 132 of magnetic medium 202. Based on the write current 312, write head 132 generates a magnetic write field 314 to form a magnet corresponding to the phase-delayed write data 306 or any suitable form of signaling or encoding for data received from host interface 302. For example, the magnetic write field 314 generates pulses at the transition of phase-delayed write data 306 to write or form a corresponding magnet of corresponding polarity in magnetic medium 202.

[0045] As an example, consider Figure 4 , Figure 4 An example time plot of write data 304 and phase delay write data 306 based on various aspects of writing according to constant density is shown at 400. Figure 4The graph or waveform also includes a clock signal 402, which can be generated or derived by the phase-locked loop (PLL) or other suitable oscillator of the read / write channel 140. Typically, the clock period 404 (or frequency) of the clock signal 402 is determined based on the rotation of the media disk 128 and remains constant. The clock period 404 forms a time base that sets the initial bit period 406 for writing data 304. In other words, the initial bit period 406 is equal to the clock period 404.

[0046] To perform constant density writing, constant density writer 142 ( Figure 3 A set of phases 408 is identified, and phase 408 divides the clock cycle 404. Figure 4 In this context, the set of phases 408 includes phases 410-1 to 410-N, where N represents a positive integer. As an example, the number of phases 410 (e.g., N) can be on the order of tens, hundreds, or thousands, and is chosen such that the constant density writer 142 can shift the phase of the data bits 412 within the write data 304 in sufficiently small increments to achieve a specific bit period for constant density writing. Typically, the clock period 404 can be an integer number of time units, while the interval between phases 410 can include any fraction of the time units 404. For example, the least significant bit of phase 410 can be a tenth of a nanosecond, a hundredth of a nanosecond, or a picosecond.

[0047] Data 412 of data 304 is written in Figure 4 The numbers are denoted as B1 to B7. The data 304 is written with an initial bit period 406 such that each data bit 412 occurs during a specific clock period 404 of the clock signal 402 (e.g., clock periods 404-1 to 404-7).

[0048] To achieve constant density writing, the constant density writer 142 modifies the initial bit period 406 associated with data bit 412 to generate phase-delayed write data 306. The phase-delayed write data 306 includes the data bit 412 associated with write data 304 and has a concentric track-based bit period 414 greater than or equal to the initial bit period 406. The constant density writer 142 sets the bit period 414 based on a selected concentric track 206 used for writing the write data 304 to compensate for the linear velocity associated with the selected concentric track 206.

[0049] To achieve a bit period 414, the constant density writer 142 adjusts the phase of the data bit 412 by various amounts. Consider a simplified example where the clock period 404 is 10 nanoseconds (ns), the number of phases is equal to 8 (e.g., N equals 8), and the bit period 414 is 13.75 ns. The increment of phase 410 is the clock period 404 divided by the number of phases (1.25 ns in this example). In other words, the first phase 410-1 occurs at the beginning of the clock period 404, the second phase 410-2 occurs 1.25 ns from the beginning of the clock period 404, the third phase 410-2 occurs 2.5 ns from the beginning of the clock period 404 (e.g., 1.25 ns from the second phase 410-2), and so on. In this case, the bit period 414 is equal to the sum of the clock period 404 and the third phase 410-3. In general, the bit period 414 can be equal to any multiple of the clock period 404 plus any phase 410.

[0050] To generate phase-delayed write data 306, the constant-density writer 142 delays the start of data bit B1 from phase 410-1 of clock cycle 404-1 to phase 410-2 of clock cycle 404-2. This delay can be based on a previous data bit (not shown). Furthermore, the constant-density writer 142 delays the start of data bit B2 from phase 410-1 of the second clock cycle 404-2 to phase 410-5 of clock cycle 404-3. In this way, data bits B1 and B2 have the same bit period 414 based on concentric tracks. This delay process continues for the other data bits 412, such that data bit B3 begins at phase 410-1 of clock cycle 404-5, data bit B4 begins at phase 410-4 of clock cycle 404-6, and data bit B5 begins at phase 410-7 of clock cycle 404-7. By delaying the start of data bits 412 within data 304, the constant density writer 142 can adjust the bit period of different concentric tracks 206 in sufficiently small increments to effectively utilize the area of ​​the media disk 128. (Constant density writer 142 reference) Figure 5 Further description.

[0051] Figure 5 An example implementation of a constant density writer 142 is shown. In the depicted configuration, the constant density writer 142 includes a write phase preprocessor 502, a unit filter 504, a final phase generator 506, and selectable delay circuitry 508. The write phase preprocessor 502 is coupled to the inputs of the constant density writer 142, the unit filter 504, and the final phase generator 506. The inputs of the constant density writer 142 can be coupled to... Figure 3Other modules within the read / write channel 140, such as a write pattern generator (not shown), are also present. A selectable delay circuit 508 is coupled between the final phase generator 506 and the output of the constant density writer 142. The output of the constant density writer 142 is coupled to a preamplifier 134. Figure 3 ) input.

[0052] The write phase preprocessor 502 determines the bit period 414 associated with different concentric tracks 206 of the media disk 128. The bit period 414 varies based on the radius of the concentric tracks 206 to maintain a specific position density 206 across the concentric tracks. The bit periods 414 of consecutive concentric tracks 206 may differ by a fraction of a nanosecond. The write phase preprocessor 502 also selects the concentric track 206 to which data is written, or receives a selection from another component of the drive control module 126, such as the read / write channel 140. The write phase preprocessor 502 can be implemented as a half-rate clock, a quarter-rate clock, or any symbol rate clock. The write phase preprocessor 502 generates initial phase data 510, stretched write data 512, and control signals 308 based on the write data 304, the bit period 414, and the clock signal 402, as follows regarding... Figure 6 Further description.

[0053] Unit filter 504 is an optional component that can be used to mitigate faults within phase-delayed write data 306. Unit filter 504 removes unit transitions within write data 304. For example, unit filter 504 searches for bit pattern 010 within write data 304 and replaces it with another pattern 000. As another example, unit filter 504 searches for bit pattern 101 within write data 304 and replaces it with another pattern 111. In some cases, the modulation or coding scheme implemented by read / write channel 140 reduces the likelihood of unit transitions occurring within write data 304. However, sometimes such patterns occur at the boundaries of the Position Error Signal (PES) or in response to high-speed AC erase. Unit transitions at the boundaries of the PES field can be removed, and such patterns in high-speed AC erase can be allowed without affecting the performance of media disk 128. Unit filter 504 generates filtered write data 514 based on stretched write data 512.

[0054] The final phase generator 506 adjusts the timing of the initial phase data 510 relative to the filtered write data 516 to provide sufficient time for the selectable delay circuit 508 to apply an appropriate phase delay to each data bit 412 and avoid introducing faults. The final phase generator 506 generates the pre-phase delayed write data 516 and the final phase data 518. The final phase generator 506 can also pass control signals 308 from the write phase preprocessor 502 to the selectable delay circuit 508.

[0055] In some cases, pre-phase delayed write data 516 is based on filtered write data 514 in order to write write data 304 to media disk 128. However, to erase previously written data, pre-phase delayed write data 516 can be derived from erase mode. Write phase preprocessor 502 can use AC erase control signal 520 to control whether final phase generator 506 generates pre-phase delayed write data 516 based on filtered write data 514 or erase mode.

[0056] To write data bit 412, final phase data 518 is generated based on initial phase data 510, as further described below. To erase previously written data, final phase data 518 can be generated such that final phase data 518 specifies a constant phase (or constant delay) of the data bits associated with the erase mode.

[0057] In some aspects, the selectable delay circuit 508 applies the phase delay identified within the final phase data 518 to data bits 412 within the pre-phase delay write data 516 to generate phase delay write data 306. The selectable delay circuit 508... Figure 3 The preamplifier 134 provides phase-delayed write data 306 and control signals 308. The operation of the constant-density writer 142 is related to... Figure 6 Further description.

[0058] As an example, consider Figure 6 , Figure 6 An example time-plot of data for each aspect written at a constant density is shown at 600. Figure 6 The graph or waveform includes clock signal 402 and write data 304. Figure 4 Furthermore, the graph or waveform includes initial phase data 510, stretched write data 512, filtered write data 514, final phase data 518, and pre-phase delayed write data 516, which can be generated by... Figure 5 The constant density writer 142 is generated.

[0059] During operation, the phase preprocessor 502 writes data from the host interface 302. Figure 3The read / write channel 140 receives the write data 304. In some cases, the read / write channel 140 modulates or encodes the write data 304 before providing it to the write phase preprocessor 502. Typically, the write data 304 includes data bits 412 associated with the initial bit period 406, such as... Figure 4 As shown. The initial bit period 406 is determined based on the clock period 404 of the clock signal 402, and the clock period 404 is generated based on the rotation of the media disk 128.

[0060] The write phase preprocessor 502 generates initial phase data 510 based on clock signal 402 and bit period 414 of the selected concentric track 206. The initial phase data 510 includes a start phase 410 associated with the corresponding data bit 412 of write data 304. The start phase 410 is denoted as P1 to P8, which are associated with bits B1 to B8, respectively.

[0061] The write phase preprocessor 502 also generates stretched write data 512 based on write data 304. Stretched write data 512 is similar to write data 304, except that stretched bit 602 is added. Figure 6 This is represented as SB. In cases where the initial phase data 510 causes the start of data bit 412 to occur later at one or more intervals of clock period 404, a stretch bit 602 is added. In some cases, consecutive stretch bits 602 are added so that bit transitions can occur at specific time intervals relative to clock period 404. By including the stretch bit 602, the information associated with data bit 412 is retained during the delay.

[0062] Unit filter 504 generates filtered write data 514 based on stretched write data 512. In this example, unit filter 504 changes the value of data bit B6 from 0 to 1 to change the 101 pattern between bits B5 to B7 in stretched write data 512 to the 111 pattern in filtered write data 514.

[0063] The final phase generator 506 generates pre-phase delayed write data 516, which is filtered write data 514. The final phase generator 506 also generates final phase data 518 based on the initial phase data 510. Specifically, the final phase generator 506 removes phase 410 that is irrelevant to the transition between 0 and 1. For example, the final phase data 518 does not include phase P2 associated with data bit B2, phase P4 associated with data bit B4, or phases P6 and P7 associated with data bits B6 and B7, respectively. The final phase generator 506 also advances the timing of phase 410 such that the phase occurs at least one clock cycle 404 before the corresponding data bit.

[0064] Selectable delay circuit 508 generates phase-delayed write data 306 based on pre-phase delayed write data 516 and final phase data 518. Specifically, selectable delay circuit 508 delays the transition between data bits 412 within pre-phase delayed write data 516 according to final phase data 518. Due to this delay, the data bits 412 within phase-delayed write data 306 have a bit period 414, which differs from the initial bit period 406 (e.g., different from clock period 404).

[0065] The constant density writer 142 can also determine a start phase (or start position) for beginning to write phase-delayed write data 306 on concentric tracks 206. Each start phase can be selected to align data bits 412 across multiple concentric tracks 206 (e.g., to align data bits 412 between concentric tracks 206 and adjacent concentric tracks 206).

[0066] Constant density writing technology

[0067] The following discussion describes constant-density write techniques for magnetic storage media that can improve write efficiency. These techniques can be implemented using any environment and entity described herein, such as read / write channel 140 or constant-density writer 142. These techniques include... Figure 7 The method 700 shown is illustrated as a set of operations performed by one or more entities.

[0068] This method is not necessarily limited to the order of operations shown in the relevant diagrams. Instead, any operation can be repeated, skipped, substituted, or reordered to achieve the various aspects described herein. Furthermore, the method can be used in whole or in part in combination with each other, whether performed by the same entity, individual entities, or any combination thereof. For example, aspects of the described method can be combined to achieve constant density writing of magnetic media by adjusting bit periods, inserting stretched bits, filtering unit transitions, and mitigating faults. References will be made in the following sections. Figure 1 Operating environment 100 Figure 2 , Figure 3 and Figure 5 The entity. This reference should not be considered as limiting the described aspects to operating environment 100, entity, configuration, or implementation, but rather as an illustration of one of various examples. Alternatively or additionally, the operation of these methods may also be performed by or through reference. Figure 8 System-on-a-chip and / or Figure 9 The entity described is implemented by the storage medium controller.

[0069] Figure 7An example method 700 for achieving constant density writing to a magnetic storage medium is described, the method 700 including operations performed at least in part by a constant density writer 142.

[0070] In 702, write data is received from the host. For example, host interface 302 receives write data from the host 304, as shown. Figure 3 As shown. The read / write channel 140 can modulate and encode the write data 304 before providing it to the constant density writer 142.

[0071] At 704, a corresponding bit period associated with multiple concentric tracks of the magnetic storage medium disk is determined. The corresponding bit period varies based on the corresponding radii of the multiple concentric tracks to maintain a specific bit density across the multiple concentric tracks. For example, the constant density writer 142 determines a corresponding bit period 414 associated with multiple concentric tracks of the media disk 128. The corresponding bit period 414 varies based on the corresponding radii of the multiple concentric tracks 206 to maintain a specific bit density across the multiple concentric tracks. In this way, the corresponding bit period 414 can compensate for differences in linear velocity associated with the multiple concentric tracks 206 and ensure that data written to the media disk 128 has the same effective bit period 212, as described above. Figure 2 As stated above.

[0072] At 706, a concentric track among multiple concentric tracks is selected for the write data. A concentric track is associated with a bit period within a corresponding bit period. For example, the constant density writer 142 or read / write channel 140 selects a concentric track 206 associated with one of the bit periods 414 for the write data 304.

[0073] At 708, the transitions between bits of the written data are delayed based on the bit period associated with the concentric track to generate phase-delayed write data. The delay in transitions effectively causes the bits of the phase-delayed write data to have a bit period associated with the concentric track. For example, the constant density writer 142 delays the transitions between bits of the written data 304 based on the bit period 414 associated with the concentric track 206 to generate phase-delayed write data 306. Therefore, the phase-delayed write data has a bit period 414 associated with the concentric track, as... Figure 4 As shown.

[0074] At 710, bits of phase-delayed write data are written along concentric tracks, giving the concentric tracks a specific density. For example, preamplifier 134 and write head 132 write phase-delayed write data 306 along concentric tracks 206, giving the concentric tracks 206 a specific density.

[0075] System-on-a-Chip

[0076] Figure 8An exemplary system-on-chip (SoC) 800 is illustrated, demonstrating various aspects of implementing constant-density writing to magnetic storage media. The SoC 800 can be implemented in any suitable device, such as a smartphone, netbook, tablet computer, access point, network-attached storage, camera, smart home appliance, printer, set-top box, server, solid-state drive (SSD), tape drive, hard disk drive (HDD), storage drive array, memory module, storage media controller, storage media interface, magnetic head disk assembly, magnetic media preamplifier, automotive computing system, or any other suitable type of device (e.g., other devices described herein). Although described with reference to an SoC, Figure 8 The entity can also be implemented as other types of integrated circuits or embedded systems, such as application-specific integrated circuits (ASICs), memory controllers, storage controllers, communication controllers, application-specific standard products (ASSPs), digital signal processors (DSPs), programmable SoCs (PSoCs), system-in-package (SiPs), or field-programmable gate arrays (FPGAs).

[0077] The SoC 800 can be integrated with electronic circuitry, microprocessors, memory, input / output (I / O) control logic, communication interfaces, firmware, and / or software that provide functionality for a computing device or magnetic storage system, such as any device or component described herein (e.g., a hard disk drive). The SoC 800 may also include an integrated data bus or interconnect (not shown) that couples various components of the SoC for data communication or routing between components. The integrated data bus, interconnect, or other components of the SoC 800 can be exposed or accessed through external ports, parallel data interfaces, serial data interfaces, peripheral component interfaces, or any other suitable data interface. For example, components of the SoC 800 can access or control external storage media or magnetic write circuitry through external interfaces or off-chip data interfaces.

[0078] In this example, the SoC 800 is shown having various components, including input / output (I / O) control logic 802 and a hardware-based processor 804 (processor 804), such as a microprocessor, processor core, application processor, DSP, etc. The SoC 800 also includes memory 806, which may include any type and / or combination of RAM, SRAM, DRAM, non-volatile memory, ROM, one-time programmable (OTP) memory, multiple-programmable (MTP) memory, flash memory, and / or other suitable electronic data storage. In some aspects, the processor 804 and the code (e.g., firmware) stored on the memory 806 are implemented as part of a storage medium controller or storage medium interface to provide various functions associated with pulse-based writing to the magnetic storage medium. In the context of this disclosure, the memory 806 stores data, code, instructions, or other information via non-transient signals and does not include carrier or transient signals. Alternatively or additionally, the SoC 800 includes a data interface (not shown) for accessing additional or stretchable off-chip storage media, such as magnetic memory or solid-state memory (e.g., flash memory or NAND memory).

[0079] The SoC 800 also includes firmware 808, applications, programs, software, and / or an operating system, which may be embodied as processor-executable instructions maintained on memory 806 for execution by processor 804 to implement the functions of the SoC 800. The SoC 800 may also include other communication interfaces, such as components for controlling local on-chip (not shown) or off-chip communication transceivers, or transceiver interfaces for communicating with such components. Alternatively or additionally, the transceiver interface may also include or implement signal interfaces to transmit radio frequency (RF), intermediate frequency (IF), or baseband frequency signals off-chip to support wired or wireless communication via transceivers, physical layer transceivers (PHYs), or media access controllers (MACs) coupled to the SoC 800. For example, the SoC 800 includes a transceiver interface configured to enable storage on wired or wireless networks, such as providing pulse-based write characteristics for network-attached storage (NAS) devices.

[0080] The SoC 800 also includes a read / write channel 140 and a constant-density writer 142, which can be implemented individually or in combination with storage components or a data interface, as shown in the figure. Alternatively or additionally, the SoC 800 may include an interface to a preamplifier and the spindle / motor assembly of a magnetic media disk drive. As described herein, the constant-density writer 142 may insert a phase delay between bit transitions to achieve aspects of constant-density writing to the magnetic storage medium. Any of these entities may be embodied as different or combined components, as described with reference to the aspects presented herein. Examples of these components and / or entities or corresponding functions are provided in the references. Figure 1The corresponding components or entities of environment 100 or Figure 2 and / or Figure 3 The constant density writer 142 can be implemented, in whole or in part, as a digital logic, circuit system, and / or processor-executable instructions maintained by memory 806 and executed by processor 804 to achieve various aspects or features of constant density writing to the magnetic storage medium.

[0081] The constant density writer 142 can be implemented independently or in combination with any suitable component or circuitry to achieve the aspects described herein. For example, the constant density writer 142 can be implemented as part of a DSP, processor / memory bridge, I / O bridge, graphics processing unit, memory controller, storage controller, arithmetic logic unit (ALU), etc. The constant density writer 142 can also be provided integrally with other entities of the SoC 800, such as with the SoC 800's processor 804, memory 806, storage media interface, or firmware 808. Alternatively or additionally, the constant density writer 142 and / or other components of the SoC 800 can be implemented as hardware, firmware, fixed logic circuitry, or any combination thereof.

[0082] As another example, consider Figure 9 , Figure 9 An example storage medium controller 900 is illustrated based on one or more aspects of pulse-based writing for magnetic storage media. Typically, the storage medium controller 900 enables a computing device 102 to access the contents of the magnetic storage medium, such as operating system, applications, or data from applications or other services. The storage medium controller also writes to and reads data from the magnetic storage medium associated with the controller.

[0083] In various aspects, the storage media controller 900 or any combination of its components can be implemented as a storage drive controller (e.g., an HDD controller or HDD chipset), a storage media controller, a NAS controller, a storage media interface, a storage media endpoint, a storage media target, or a storage aggregation controller for magnetic storage media, solid-state storage media, etc. (e.g., a hybrid SSD / HDD storage system). In some cases, the storage media controller 900 is related to a reference... Figure 8The described SoC 800 is similarly implemented, or implemented along with components of the SoC 800. In other words, an instance of the SoC 800 can be configured as a storage media controller, such as a storage media controller 900 for managing magnetic storage media. In this example, the storage media controller 900 includes input / output (I / O) control logic 902 and a processor 904, such as a microprocessor, microcontroller, processor core, application processor, DSP, etc. The storage media controller 900 also includes a host interface 906 (e.g., a SATA, PCIe, NVMe, or Fabric interface) and a storage media interface 908 (e.g., a magnetic media interface or a head disk assembly (HDA) interface) that respectively enable access to the host system (or infrastructure) and the storage media. In this example, the storage media interface 908 includes separate instances of a spindle interface 910 and a preamplifier interface 912 to enable communication with the head disk assembly of the media drive.

[0084] In some respects, when managing or enabling access to the storage medium coupled to the storage medium interface 908, the storage medium controller 900 implements various aspects of constant-density writing to the magnetic storage medium. The storage medium controller 900 provides a storage interface to the host system via the host interface 906, through which it can receive storage access commands from the host system, such as data to be written to the magnetic storage medium. Figure 9 As shown, the storage medium controller 900 also includes a servo control unit 138, a read / write channel 140, and a constant density writer 142. The servo control unit 138 is operatively coupled to the spindle interface 910 and provides spindle or voice coil control to the magnetic media driver. In this example, the read / write channel 140 and the constant density writer 142 are operatively coupled to the preamplifier interface 912 and provide phase-delayed write data 306 and / or pulse write control signals to the preamplifier circuitry of the media driver. In some aspects, the firmware or logic of the processor 904 and the storage medium controller 900 is implemented to provide various data write or processing functions associated with pulse-based writing of the magnetic storage medium.

[0085] The constant density writer 142 of the storage medium controller 900 can be implemented independently, as shown, or in combination with the processor 904, the read / write channel 140, or the storage medium interface 908. Depending on the aspect, the constant density writer 142 inserts a phase delay between bit transitions to achieve aspects of constant density writing to the magnetic storage medium. Examples of these components and / or entities or corresponding functions are provided in the references. Figure 1 The corresponding components or entities of environment 100 or Figure 2 and / or Figure 3The corresponding configuration is described as shown. The constant density writer 142 can be implemented, in whole or in part, as processor-executable instructions maintained by the controller's memory and executed by the processor 904 to implement various aspects and / or characteristics of pulse-based writing of the magnetic storage medium.

[0086] Although the subject matter has been described in language specific to structural features and / or methodological operations, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific examples, features, or operations described herein, including their order of execution.

Claims

1. An apparatus including a constant density writer, the constant density writer being configured to: Receive write data, the write data having an initial bit period based on the angular velocity of a disk of magnetic storage medium, the disk having a specific positioning density across multiple concentric tracks; Phase-delayed write data is generated by delaying the transitions between bits of the write data according to a bit period associated with one of the plurality of concentric orbits, wherein the bit period differs from the initial bit period; and The phase-delayed write data is sent to the magnetic medium writer so that the magnetic medium writer can write the phase-delayed write data into the concentric orbit, so that the concentric orbit has the specific positioning density.

2. The apparatus of claim 1, wherein the constant density writer is further configured to: Receive other write data having the initial bit period; Additional phase-delayed write data is generated by delaying the transitions between bits of the other write data according to another period associated with another concentric orbit among the plurality of concentric orbits, wherein the other period differs from the initial bit period and the bit period; and The write data with the other phase delay is sent to the magnetic medium writer so that the magnetic medium writer can write the write data with the other phase delay to the other concentric track, so that the other concentric track has the specific positioning density.

3. The apparatus of claim 2, wherein the effective bit period of the data bits written along the concentric tracks is approximately equal to the effective bit period of the other data bits written along the other concentric tracks.

4. The apparatus of claim 1, wherein the constant density writer is further configured to: Before generating the write data with the phase delay, initial phase data is generated based on the bit period and the write data. The initial phase data indicates the start phase of the bit within the write data, and the start phase is based on the phase of the initial bit period. Stretched write data is generated based on the initial phase data by inserting at least one stretch bit between the first bit and the second bit of the written data, wherein the insertion of the at least one stretch bit effectively shifts the starting phase of the second bit by a multiple of the initial bit period; and The phase-delayed write data is generated by delaying the transitions between bits of the stretched write data based on the initial phase data.

5. The apparatus of claim 4, wherein the constant density writer is further configured to: Before generating the phase-delayed write data, filtered write data is generated by filtering individual bit transitions within the bits of the stretched write data; and The phase-delayed write data is generated by delaying the transitions between bits of the filtered write data based on the initial phase data.

6. The apparatus of claim 1, wherein the plurality of concentric orbits have corresponding bit periods that vary based on the corresponding radii of the plurality of concentric orbits.

7. The apparatus of claim 6, wherein the corresponding bit period is greater than or equal to the initial bit period.

8. The apparatus according to claim 6 or 7, wherein at least one bit period in the respective bit period is not a multiple of the initial bit period.

9. The apparatus according to claim 6 or 7, wherein the corresponding bit periods of two consecutive concentric orbits in the plurality of concentric orbits differ by a fraction of a nanosecond.

10. The apparatus according to any one of the preceding claims, wherein the apparatus comprises a system-on-a-chip, the system-on-a-chip comprising the constant density writer.

11. A method for writing to a magnetic storage medium at a constant density, the method comprising: Receive write data, the write data having an initial bit period based on the angular velocity of a disk of magnetic storage medium, the disk having a specific positioning density across multiple concentric tracks; Phase-delayed write data is generated by delaying the transitions between bits of the write data according to the bit period associated with the concentric orbits of the plurality of concentric orbits, the bit period being different from the initial bit period; as well as Write the phase-delayed write data along the concentric orbit, so that the concentric orbit has a specific positioning density.

12. The method of claim 11, further comprising: Receive other write data having the initial bit period; Additional phase-delayed write data is generated by delaying the transitions between bits of the other write data according to another period associated with another concentric orbit of the plurality of concentric orbits, wherein the other period is different from the initial bit period and the bit period; and Write data with the other phase delay along the other concentric track, such that the other concentric track has the specific positioning density.

13. The method of claim 12, wherein writing the phase-delayed write data and writing the other phase-delayed write data comprises: Data bits are written along the concentric track and the other concentric track, such that the data bits have the same effective bit period along the concentric track and the other concentric track.

14. The method of claim 11, further comprising: Before generating the write data with the phase delay, initial phase data is generated based on the bit period and the write data. The initial phase data indicates the start phase of the bits within the write data, and the start phase is based on the phase of the initial bit period. Stretched write data is generated based on the initial phase data by inserting at least one stretch bit between the first bit and the second bit of the written data. The insertion of the at least one stretch bit effectively shifts the starting phase of the second bit by a multiple of the initial bit period. as well as The phase-delayed write data is generated by delaying the transitions between bits of the stretched write data based on the initial phase data.

15. The method of claim 14, further comprising: Before generating the phase-delayed write data, filtered write data is generated by filtering individual bit transitions within the bits of the stretched write data. as well as The phase-delayed write data is generated by delaying the transitions between bits of the filtered write data based on the initial phase data.

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