Abstract: A method and apparatus for real-time filtering of a position error signal in a servo system of a disk drive. Pre-calculated periodic components of the position error signal (PES) are used as future values in a real-time filter, preferably a real-time recursive median filter. This minimizes the amount of time-lag between obtaining the raw PES measurement from the disk surface and the providing the corresponding filtered PES output. This reduced time-lag minimizes the effect on the phase margin (PM) and results in improved servo stability. The invention can be used not only in servo systems in disk drives, but also in servo systems of other mechanical moving storage devices and in servo systems of rotating mechanical machinery in general, where the signal to be filtered may be a position error, velocity error, acceleration error, and the like.

Abstract: The present invention overcomes the problems that accompany the use of ramps to load and unload transducer carrying sliders in rigid magnetic disk data storage devices. The tracks in the region where the slider loads and unloads are read and the errors recorded following each slider loading operation. One technique is to track the error increase and identify imminent device failure when the rate of error increase during a given number of the most recent slider load cycles exceeds a threshold value. In another mode, a dedicated sequence of tracks is recorded at an increased linear density to assure that read errors occur to enable a more effective comparative evaluation. This makes possible a two stage evaluation, a first threshold number of errors indicative of degrading performance which initiates lower actuator velocity to inhibit further degradation and a second threshold error quantity that indicates imminent catastrophic failure and triggers a warning to the system user.

Abstract: Disclosed is a disk drive having at least one disk for storing data. The disk drive includes at least one transducer for reading or writing data to or from the disk. The transducer is attached to an actuator which positions the transducer with respect to the disk. The actuator includes a controllable motor which is used to move the actuator and the transducer attached thereto. The disk drive also includes a ramp for off loading the transducer or for parking the transducer off of the surface of the disk. Also disclosed is apparatus and methods for measuring and controlling the movement of the actuator and attached transducer while the transducer is coming from a position off of the ramp and onto the surface of the disk.

Abstract: A multimedia server system and a method for communicating multimedia programming to distantly situated media control systems are disclosed. The multimedia server system includes a mass storage library for storing a plurality of multimedia programs. A multimedia program is coded in accordance with a predetermined compression standard and stored in a compressed digital format as sequentially ordered discrete program segments in the mass storage library, with each of program segments being representative of a unique portion of the multimedia program. A video parser organizes the sequentially ordered program segments of a multimedia program into a custom ordered series of program segments preferably including non-sequentially and sequentially ordered program segments in accordance with configuration parameters associated with the configuration and presentation control features of a media control system requesting the multimedia program.

Abstract: A method and apparatus for controlling a multiple-stage actuator for a disk drive which does not require an additional sensor for measuring the relative position between adjacent actuator stages. In a two-stage actuator system, a position-type secondary actuator (SA) rides piggyback on a primary actuator (PA). The repeatable runout is measured and used as a feedforward signal to the PA. If the PA is a rotary actuator, the feedforward signal is preferably arc corrected for the arc that the head transverses from the inner radius to the outer radius of the disk. Added to the feedforward signal is the moving average of the drive signal applied to the SA. Because the SA is of the position-type having a neutral position, this moving average is proportional to the time cumulative drift present in the two-stage actuator system, and forces the PA in a direction that minimizes deviation of the SA from its neutral position.

Abstract: The present invention is a method and apparatus for positioning a magnetoresistive (MR) head relative to a storage medium in a storage device. The storage medium is mounted in the storage device to allow relative movement between the MR head and the storage medium. The storage medium includes servo information provided to induce a thermal response in the MR head. A controller controls the relative movement between the MR head and the storage medium using the thermal response induced in the MR head.

Abstract: A method and apparatus for real-time filtering of a position error signal in a servo system of a disk drive. Pre-calculated periodic components of the position error signal (PES) are used as future values in a real-time filter, preferably a real-time recursive median filter. This minimizes the amount of time-lag between obtaining the raw PES measurement from the disk surface and the providing the corresponding filtered PES output. This reduced time-lag minimizes the effect on the phase margin (PM) and results in improved servo stability. The invention can be used not only in servo systems in disk drives, but also in servo systems of other mechanical moving storage devices and in servo systems of rotating mechanical machinery in general, where the signal to be filtered may be a position error, velocity error, acceleration error, and the like.

Abstract: The present invention is a method and apparatus for positioning a dual element magnetoresistive (MR) head relative to a storage medium in a storage device. The MR head has first and second MR elements. The storage medium is mounted in the storage device to allow relative movement between the MR head and the storage medium. The storage medium includes servo information provided to induce first and second thermal responses in the MR elements. A controller is coupled to the MR head and controls the relative movement between the MR head and the storage medium using the first and second thermal responses in the MR elements.

Abstract: Apparatus and a method are provided for mapping aperities or protruding disk defects in a data storage disk file. A protruding disk defect is identified and a head and disk interference value is measured. The measured head and disk interference value is compared with a predetermined threshold value. A severity value is determined responsive to the compared values and stored with a location of the identified protruding disk defect. A no-idle zone is defined relative to the location of the identified protruding disk defect based upon the severity value and a geometry of an airbearing slider. Evasive maneuvering is performed to avoid slider and transducer head contact with the identified protruding disk defect.

Abstract: Rotary actuator arc compensation correction method and apparatus are provided for a direct access storage device (DASD). A reference feedforward correction signal is generated at each of a plurality of sectors around a predetermined track on a disk surface. A specific selected track is identified, and both magnitude and phase of the generated reference feedforward correction signal are modified to correct for the arced trajectory caused by the rotary actuator at the specific selected track. Improved actuator servo control is provided by using pseudo sector compensation to interpolate the feedforward correction signal between servo sectors.

Abstract: A method and apparatus for calibrating a thermal response of an MR element spaced apart from a surface of a data storage disk is disclosed. A calibration feature, such as a depression, is provided on a surface of the disk. Signals are read from the calibration depression and a location on the disk surface other than the calibration depression using the MR element. Magnetic and thermal spacing signals are produced using the readback signals. A calibrated thermal spacing signal is produced using the magnetic spacing signals and the thermal spacing signals, such that the calibrated thermal spacing signal varies proportionally or, alternatively, linearly with respect to variations in spacing between the MR element and the disk surface. The calibration methodology is preferably performed in-situ a data storage system.

Abstract: Disclosed is a disk drive having at least one disk for storing data. The disk drive includes at least one transducer for reading or writing data to or from the disk. The transducer is attached to an actuator which positions the transducer with respect to the disk. The actuator includes a controllable motor which is used to move the actuator and the transducer attached thereto. The disk drive also includes a ramp for off loading the transducer or for parking the transducer off of the surface of the disk. Also disclosed is apparatus and methods for measuring and controlling the movement of the actuator and attached transducer while the transducer is coming from a position off of the ramp and onto the surface of the disk.

Abstract: A disk storage device in which two or more discrete disk velocities are used is disclosed. The disk velocity is selected using operating environmental conditions. Various types of sensors may be used to detect the environmental conditions or the environmental conditions may be input by a user. The allocation of track locations on a disk into zones reduces the number of zone bit frequencies the storage device must handle when multiple frequency zones are used in connection with the various spindle speeds.

Abstract: A multimedia direct access storage device and a method for transferring source program signals representative of a compressed digital multimedia program to and from the direct access storage device are disclosed. A multimedia program is transmitted from a multimedia server as a custom ordered series of discrete program segments and received by the multimedia direct access storage device, which buffers the compressed program segments for subsequent presentation on a local display monitor. The multimedia direct access storage device is preferably incorporated as a component of a local set-top control system for buffering a predetermined number of compressed program segments received from the multimedia server, some of which may be non-sequentially ordered and others of which may be sequentially ordered. A novel formatting methodology provides for the sequential presentation of the program segments asynchronously distributed on one or more data storage disks disposed in the direct access storage device.

Abstract: An apparatus and method for reading an information signal from a magnetic storage medium using a magnetoresistive (MR) element, modifying the signal such that a thermal component of the signal representing a thermal response of the MR element is degraded, and altering the modified signal to produce a restored thermal signal substantially representative of the thermal component of the signal read from the storage medium. The information signal induced in the MR element is communicated from the MR element to an arm electronics (AE) module having a highpass filtering behavior. The AE module passes content of the information signal other than the thermal component content, thereby degrading the thermal component of the information signal. An inverse filter, implemented using an infinite impulse response (IIR) filter, receives the highpass filtered signal from the AE module and produces a restored thermal signal substantially representative of the thermal component of the information signal.

Abstract: A memory device using at least one disk is disclosed the memory device uses a banded disk. The disk is optimally banded for use in a multiple frequency zoned disk storage device. The allocation of track locations into zones on the disk reduces the number of zone bit frequencies the storage device must handle when the disk is rotated at more than one discrete disk velocity.

Abstract: The present invention is a method and apparatus for positioning a magnetoresistive (MR) head relative to a storage medium in a storage device. The storage medium is mounted in the storage device to allow relative movement between the MR head and the storage medium. The storage medium includes servo information provided to induce a thermal response in the MR head. A controller controls the relative movement between the MR head and the storage medium using the thermal response induced in the MR head.

Abstract: An array of direct access storage devices (DASD's) such as disk drive units includes a temperature sensor for sensing the operating temperature of each DASD. The operating temperatures of the DASD's of the array are equalized by allocating frequently accessed data to drives with relatively low operating temperature and allocating infrequently accessed data to drives with relatively high operating temperatures. Operating temperature information is used to identify a DASD that has a high probability of failure and the DASD can be shut down for replacement prior to actual failure by moving all data from that DASD to one or more other DASD's of the array.

Abstract: A disk drive includes an error and operating condition tracking mechanism for later analysis. A device controller for the disk drive has access to non-volatile storage. The non-volatile storage is partitioned into one or more areas for storage of condition and error information. A main partition is used for storage of cumulative operating statistics. A secondary partition is used for logging time stamped condition records, with the accumulative count register being used to provide the time stamp. A last in last out partition is used by the device controller to store time stamped error occurrence records for the data storage system.

Abstract: An apparatus and method for effectuating local reception and processing of source program signals representative of a compressed digital multimedia program received from a remote multimedia server are disclosed. The multimedia server transmits a selected multimedia program as a custom ordered series of discrete program segments to a local set-top control system, which buffers and decompresses the compressed program segments for presentation on a local display monitor. A local set-top control system preferably includes a direct access storage device adapted to buffer a predetermined number of compressed program segments received from a multimedia server, some of which may be non-sequentially ordered and others of which may be sequentially ordered. A novel formatting methodology provides for the sequential presentation of the program segments asynchronously distributed on one or more data storage disks disposed in the direct access storage device.