Abstract: The disclosure is directed to a method for identifying and classifying data surface defects on the disks of a rigid disk data storage device. By partitioning each surface into cells and sub-sampling every Nth track, the number and location of defects can be determined. The number of stored defects is then examined to determine whether clusters of contiguous cells exist wherein defect totals exceed a predetermined threshold number. This enables the location of clusters on multiple surfaces to be examined for axial alignment, radial alignment or random occurrence as an indication of the source of damage. To obtain further verification of the data surface condition, the location of a defect cluster can be scanned using a utility that evaluates each track within the defect cluster or area.

Abstract: A method and apparatus for estimating the value of a slider airbearing resonance frequency involves obtaining a readback signal from a data storage medium over a plurality of complete airbearing periods and estimating the value of an airbearing resonance frequency using the readback signal. In one embodiment, a discrete signal segment comprising a plurality of frequency transform components is produced using the readback signal information, and the value of the airbearing resonance frequency is estimated using spectral leakage in the discrete signal segment. A ratio of the magnitudes of a first DFT component to a second DFT component is computed at each of a plurality of sampling rates. Each of these sampling rates is defined by a number of samples per average airbearing cycle multiplied by a frequency falling within a range of expected airbearing frequencies associated with a given implementation.

Abstract: A method and apparatus for calibrating a thermal response of a magnetoresistive element is provided. In accordance with one embodiment of the invention, a thermal spacing signal is read using an MR element spaced apart from a surface of a moving storage medium. From the thermal spacing signal a signal value and calibration value are produced. Using the signal value and the calibration value a calibrated signal value is produced. The calibrated signal value may, for example, be compared against a pre-determined threshold to detect surface defects on the storage medium.

Abstract: A bar coded magnetic recording pattern uniquely identifying the disk of a disk drive is disposed, at the time the disk is single disk tested and accepted, in a reserved area that is not used for data recording by the disk drive assembly. The identifying recording is disposed in a reserved region that is accessible by the magnetic transducer of the disk drive. The identifying recording may be read to determine the orientation of the disk in the disk drive and may be read to positively identify the disk to permit repair, recall or data transfer from specifically identified disks without shut down and/or disassembly of the disk drives incorporating the designated disks.

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: 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: A method and apparatus are provided for detecting handling damage in a direct access storage device (DASD). The DASD has at least two magnetic disk surfaces provided by at least one disk mounted for rotation, and a corresponding transducer mounted for movement across each disk surfaces. A predefined test is performed to identify magnetic surface defects on each of the disk surfaces. The identified magnetic surface defects are utilized to identify cosited defects on at least two magnetic disk surfaces. Responsive to identifying a predefined number of cosited defects on at least two magnetic disk surfaces, handling damage is reported to the user. The method for detecting handling damage is performed responsive to a user request and following predetermined events during use of the direct access storage device.

Abstract: In a rotating magnetic disk storage device which uses an imbedded servo pattern for positioning an actuator, each transducer head comprises two magnetoresistive read elements, the read elements being separated by an insulating layer. The read elements are of different widths, the narrower element being used to read data, and the wider element being used to read servo patterns which locate the track centerline. The read elements are preferably deposited in layers on the rear of the slider body, with a thin-film inductive write head deposited in layers over the read elements. Preferably, the read elements are connected to three lead wires: a common ground lead, and separate sense leads. The sense amplification electronics alternatively sense resistance changes in one element or the other as the head passes over data or servo patterns. Because the narrow read element is used for reading data, noise due to reading too close to the edge of the track can be reduced.

Abstract: An apparatus and method for detecting low flying read/write heads provides for the detection of contact between an air bearing slider/transducer assembly and a surface feature developed on a surface of a data storage disk. The apparatus includes a transducer disposed on an air bearing slider. An actuator is coupled to the slider/transducer assembly typically by employment of a head suspension assembly. The processor, in response to position error signals developed from servo information provided on the disk surface, moves the actuator and slider/transducer assembly to prescribed disk surface locations. The processor further processes non-repeatable position error signal values developed at a plurality of disk surface locations to detect an occurrence of contact between the slider/transducer assembly and a surface feature arising from the disk surface.

Abstract: An apparatus and method for reading an information signal from a magnetic storage medium using a magnetoresistive (MR) head, and separating a thermal signal component and, if present, a magnetic signal component from the information signal. A signal separation/restoration module eliminates distortion in the magnetic signal component of a readback signal induced by a thermal signal component of the readback signal. A finite impulse response (FIR) filter may be employed in the signal separation/restoration module to eliminate the distortion in the magnetic signal. The signal separation/restoration module may be employed to extract the thermal signal component from the readback signal. In one configuration, an MR head is coupled to an arm electronics (AE) module, having a highpass filtering behavior, and a signal separation/restoration module that includes an inverse filter having a transfer function inverse to that of the effective highpass filter of the AE module.

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: The present invention generally provides a method and system for correcting for offset in a position error signal. In accordance with one embodiment of the invention, the readback signals dependent upon a read sensitivity profile of a read head are generated by moving the read head over a correction track. Using the readback signals, a characteristic value of the read sensitivity profile is determined. The characteristic value of the read sensitivity profile is used to adjust raw position error signals generated using the read head. The characteristic value may, for example, be determined from one or more data points from a cumulative sum data set. In accordance with another embodiment of the invention, a storage device is provided. The storage device includes a read head and a storage medium which includes a correction track and which is mounted to allow relative movement between the read head and the storage medium. The storage device further includes a servo control system.

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 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: Storing data on a data processing system is done upon generation of a data file by displaying a user interface allowing user selection of storage criteria for the data file. Responsive to user selection of storage criteria for a file determining a physical format type for the file from a plurality of available physical format types. Then the file is stored on a direct access storage device as at least a first record conforming with the determined physical format type.

Abstract: A method and apparatus for optimizing the seek/settle performance of a storage device. The present invention measures the seek/settle performance for each individual head and selects the heads with the best seek/settle performance, i.e., access performance. The invention includes a processor for calculating velocity deviations for each of the plurality of heads to determine a set of suitable seek heads from the plurality of heads, a head selection circuit for switching from a current head to a preferred head from the set of suitable seek heads and an actuator controller for seeking with the preferred head to a virtual track corresponding to a target track. The processor calculates a preferred/target runout difference for smoothing the settle of the preferred head and the head selection circuit switches from the preferred head to a target head aligned with the target track.

Abstract: A magnetic disk drive includes redundant data written at a plurality of out of phase angular locations to reduce the latency and enhance performance during a read operation. The loss of recording capacity is reduced by increasing the data density to achieve the same soft error rate standard required for single recording. Dual recording also allows different recording codes to be used at the duplicated locations to thereby have the more highly stressed code words occur at different locations in the data to further reduce the possibility of an error. The redundant recording can be used in one portion of the media and normal recording used in another media portion to enable selection of the recording technique in accordance with the type of data being stored. The size of the normal and redundant recording portions can be controlled by the format operation and the user of the disk drive can intervene to designate the size of the redundant and normal media recording portions effected during the format operation.

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: 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: 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.