79 results about "Direct-access storage device" patented technology

Digital data records are stored on a direct access storage device (DASD) in emulation of sequential-access media, the efficiency of storage and access of the data being improved by using a volume trailer containing various statistics about the records. Data is preferably stored in records, logically assembled into record groups. Interspersed with the records, there may be one or more marker codes, which function like tape marks among the various data records. The volume trailer contains pointers to each record group, record counts for each group, marker code counts for each group, and may also include fields showing whether records in a given record group are of equal length. The volume trailer may also include a volume trailer "tail", including a byte count for the entire volume trailer, and a unique sequence identifying the volume trailer. Statistics contained in the volume trailer enable substantially more efficient access of the data by a DASD. For example, record groupings, group counts, and/or marker code counts may be employed to perform operations such as locate, forward space file, and backward space file.

A RAID system which functions despite any single point of failure is disclosed. The system has two or more controllers, a multiplicity of direct access storage devices arranged in racks, redundant connectors throughout, and an independent backplane, cables, power supply, and cooling system for each controller and for each rack of direct access storage devices. In a second embodiment, no backplane or midplane is included in the RAID system; rather each controller is connected directly with the direct access storage devices.

A portion of digital data records are stored on a direct access storage device (DASD) in emulation of sequential-access media when the parent digital data records are transferred to a sequential-access media. The efficiency of storage and access to the data portion is improved by random-access recall of the data in the data portion, and by constructing a data portion trailer containing various statistics about the records for referencing the digital data and advancing to target data. The volume data portion trailer is constructed as read forward and forward space block operations are performed. Data is preferably stored in logically assembled records. Interspersed with the records, there may be one or more marker codes, which function like tape marks among the various data records. The volume trailer may contain pointers to each record, a record count and marker codes for the data portion. Statistics contained in the data portion trailer enable substantially more efficient access of the data by a DASD.

Disclosed is a system for caching data. After determining a sequential access of a first memory area, such as a direct access storage device (DASD), a processing unit stages a group of data sets from the first memory area to a second memory, such as cache. The processing unit processes a data access request (DAR) for data sets in the first memory area that are included in the sequential access and reads the requested data sets from the second memory area. The processing unit determines trigger data set from a plurality of trigger data sets based on a trigger data set criteria. The processing unit then stages a next group of data sets from the first memory area to the second memory area in response to reading the determined trigger data set.

Disclosed is a system for performing input/output (I/O) operations with a processing unit. A processing unit, such as a host system, determines a base and associated alias addresses to address an I/O device, such as a direct access storage device (DASD). The processing unit associates the determined base and alias addresses to the I/O device. The association of base and alias addresses is maintained constant for subsequent I/O operations until the processing unit detects a reassignment of the association of base and alias addresses. The processing unit then determines an available base or alias address to use with an I/O operation and may concurrently execute multiple I/O operations against the I/O device using the base and alias addresses.

Disclosed is a system for dynamically assigning alias addresses to base addresses referencing an I/O device, such as a direct access storage device (DASD). In the system, at least one base control block indicates a base address and a plurality of alias control blocks indicate a plurality of alias addresses. Each control block is associated with an address for addressing an I/O device. A processing unit, such as a host computer system, processes at least one alias control block associated with the I/O device and determines a base control block associated with the I/O device with which the alias control blocks are associated. The processing unit then binds at least one alias control block to the determined base control block. The bound base and alias control blocks provide different addresses to address the same I/O device. Further, the bound base and alias addresses address the same I/O device for subsequent I/O operations until the processing unit detects a reassignment of the association of base and alias addresses.

Disclosed is a system and method for processing a data access request (DAR). A processing unit, such as a storage controller, receives a DAR, indicating data to return on a channel, such as a channel connecting to a host system, and priority information for the received DAR. The processing unit retrieves the requested data for the received DAR from a memory area, such as a cache or direct access storage device (DASD), and determines whether there is a queue of data entries indicating retrieved data for DARs to transfer on the channel. The queued DARs include priority information. The processing unit processes at least one data entry in the queue, the priority information for the data entry, and the priority information for the received DAR to determine a position in the queue for the received DAR. The processing unit then indicates that the received DAR is at the determined position in the queue and processes the queue to select retrieved data to transfer on the channel to the host system.

Disclosed is a method and computer program device for dynamically managing the assignment of alias addresses to base addresses referencing an input/output (I/O) device, such as a direct access storage device (DASD). Two distinct methods are disclosed. In one method, alias addresses are assigned based on the performance of the I/O devices. In this method, alias addresses are assigned to highly utilized devices, as indicated by device performance data, in order to maximize the efficient utilization of I/O device resources. In a second method, workload management principles are utilized to assign alias addresses. In this method, a correlation is made between each I/O device and the service classes utilizing each device. As in the first method, performance data is generated for each I/O device. Alias addresses are assigned to I/O devices experiencing queue delays as indicated by their performance data, if the device is associated with a service class that has failed to meet one or more processing goals. These methods may operate on a single host, or in a multi-host environment. The methods may be operated individually, or concurrently. Methods are disclosed to manage contention between concurrently operating assignment methods, and between multiple hosts concurrently operating one or more assignment methods.

In cold weather, the higher torque required for normal spinning operation of a spindle motor assembly in a direct access storage device due to the increased viscosity of the grease, is overcome by localizing the heating to the spindle motor assembly to reduce the viscosity of the grease, and then let a disk driven self heat during and after spin-up of the spindle motor assembly.

A method and apparatus for reducing space allocation failures in a computer system that utilizes direct access storage devices to store data. The method comprises the steps of determining if authorization has been given to attempt to allocate an initial space request over more than one volume, and, if so, attempting to allocate space on a plurality of volumes. If the initial space request cannot be allocated on a plurality of volumes, the initial space request is reduced by a preset percentage, the five-extent limit is removed and an attempt is made to allocate the reduced space request on the plurality of volumes with the five extent limit removed. Alternatively, if authorization has not been given to attempt to allocate the initial space request over more than one volume, the initial space request is reduced by a preset percentage, the five-extent limit is removed and an attempt is made to allocate the reduced space request on a single volume.

A method and apparatus are provided for implementing enhanced data channel performance using a read sample buffer in a direct access storage device (DASD). Disk data is read and stored in the read sample buffer. When a data recovery procedure (DRP) starts, the stored disk read data in the read sample buffer is detected. Error correction code (ECC) checking of the detected sample buffer disk data is performed to identify correctly recovered data. Using the disk read data stored in the read sample buffer enables data recovery without identification of a sync word. Also using the disk read data stored in the read sample buffer enables data recovery with changed channel data detection settings to recover the data. The read sample buffer can be used for accumulating read disk data from more than one read operation so that at least some channel noise is averaged out.

A media-rendering apparatus for real-time streaming of audio/video (AV) data to a media-player having one or more input direct-access-storage-device (DASD) interfaces, the apparatus including a real-time AV data source unit, an input frame buffer operatively coupled with the real-time AV data unit, an AV real-time encoder, an encoded-frames buffer, a power source, a storage-device content emulator and a DASD interface device for communicating with the media-player. Preferably, power is provided through the DASD interface device.

A computer chassis is provided that may accommodate direct access storage device cages for various form factors. A 3.5-inch direct access storage device (DASD) cage may support 3.5-inch serial attached SCSI (SAS) direct access storage devices. The 3.5-inch SAS DASD cage includes a DASD backplane with a main connector and eight SAS drive connectors. A SFF direct access storage device cage may support SFF SAS direct access storage devices. The SFF SAS DASD cage may include a DASD backplane with a main connector and two port expanders. The port expanders may support up to twelve SAS DASD with redundant SAS channel wiring and one external 4-channel SAS port.

An enclosure assembly and system are provided for implementing cover-mounted, auto-docking for multiple DASD configurations in information technology equipment. A user selected direct access storage device (DASD) configuration is mechanically attached to an enclosure cover. A cover interposer card is mechanically attached to the enclosure cover and electrically connected to each DASD in the user selected DASD configuration. An electrical connector mates with the cover interposer card as the cover is installed through a sliding motion with a chassis and base planar of the enclosure assembly. A flexible cable interconnect attached to the mating electrical connector is connected to the base planar. The enclosure assembly enables high density, high performance modular server architectures without compromising processor performance or planar electrical architecture.

An attached storage media link has a self-timed interface (STI) in which a clock signal clocks bit serial data onto a parallel, electrically conductive bus and the clock signal is transmitted on a separate line of the bus. The received data on each line of the bus is individually phase aligned with the clock signal, providing a high speed, cost effective interface to a direct access storage device.

A method and apparatus are provided for implementing in situ low flyheight warning in a direct access storage device (DASD). For each head in the DASD, a readback amplitude ratio is identified from two different disk radii. The initial ratio value is stored for each head in the DASD. During operation of the DASD, readback amplitude is monitored and an operating readback amplitude ratio is identified from two different disk radii. A change between the initial ratio value and the operating readback ratio is calculated and compared with a threshold value to identify a low-flying slider. A warning is generated responsive to the change value being greater than the threshold value.

A method and apparatus are provided for variable spindle rotation speed in a direct access storage device (DASD). The direct access storage device (DASD) includes a multi-phase, brushless, direct current (DC) spindle motor. Speed and commutation control signals are applied to a plurality of spindle motor drivers for normally operating the plurality of spindle motor drivers in saturation mode while performing read and write operations. A spindle rotational speed is detected and compared with a predetermined spindle speed range. Responsive to the detected spindle rotational speed being within said predetermined spindle speed range, normal operations of the direct access storage device (DASD) are enabled. One or more write sync fields are provided on each surface of a magnetic disk media. The write sync field is used for timing write operations in the direct access storage device.

A method for controlling write current to a write head during data write on a hard disk drive is disclosed. A direct access storage device includes a rotating storage medium in which data are magnetically written, a write head for writing data in the rotating storage medium, and a write current control circuit for changing write current-value settings to be supplied to the write head according to a predetermined elapsed time from the beginning of a write operation.

A method of generating a higher-order trigonometric sequence, by constructing a table having a first-order trigonometric sequence, indexing the table to yield a different sequence based on an order number of a desired higher-order harmonic, and catenating values in the table according to the different sequence to yield a higher-order trigonometric sequence whose order is the order number. The table may be a first-order sine sequence, with the method yielding a higher-order sine sequence, or the table may be a first-order cosine sequence, with the method yielding a higher-order cosine sequence. The table has a period N, and indexing is accomplished by computing pointer indices equal to (k*n)mod(N), where k is the order number, and 0<=n<N. In the special case where N is a multiple of 4, a single table may be used for both higher-order sine and higher-order cosine sequences. This method may be applied to the calculation of a local PES-correction value for at least one track of a direct access storage device. The local PES-correction value is then used to position a read/write head of the direct access storage device over the track. The PES-correction value for the track may be stored on a sector of the direct access storage device.

A computer program product for performing testing of a simulated direct access storage device in a testing simulation environment is disclosed. The computer program product provides a software representation of a plurality of hardware components within the simulated direct access storage device. The computer program product also uses a control program module within the testing simulation environment, wherein the control program module interacts with the software representation of the plurality of hardware components, and a testing program for interacting with the control program module and the software representation of the plurality of hardware components. In response to detection of an occurrence of a pre-selected event within the simulated direct access storage device, one or more codes are sent from the testing program to the software representation of the plurality of hardware components and whether or not a response by the control program module to the one or more codes is correct is determined.