International Business Machines Corporation

Other

Hitachi Global Storage Technologies

Earl Albert Cunningham

Hal Hjalmar Ottesen

Thomas C Christensen

Dana H Brown

Jodie Ann Christner

Zine-Eddine Boutaghou

Albert John Wallash

Richard Greenberg

Kevin Jack Erickson

Steven Harry Voss

David Malcolm Hannon

Jeffrey B Brown

Nickolas Christopher Apuzzo

Raymond Patrick Mallette

Paul Sheldon Tyler

Samir Elias Abboud

Dean C Palmer

Wayne A Rogelstad

Albert W Vinal

Timothy C Reiley

Mark David Hagen

John Jeffrey Stephenson

Joe Martin Poss

Long-Sheng Fan

Gregory J Kerwin

Gordon James Smith

Jonathan Darrel Coker

David Timothy Flynn

Michael Scott Hicken

James Wilson Rae

Peter John Windler

William G Crouse

Ronald L Soderstrom

Thomas W Glaser

Todd Barry Anderson

Gerald M Heiling

Michael John Shea

Clark A Anderson

Mark Andrew Bergquist

Townsend H Porter, Jr

Richard H Estry

Richard Fred Harwood

Russell A Billings

Jay Michael Mosbrucker

Daniel D Reno

James M Thompson

Richard C Jaworski

Bradley Ellsworth Hanson

Gerald Lawrence Cadloni

David E Cutshall

Jeffrey R Roepke

Dana Henry Brown

Russell Allen Billings

George Willard Vanleeuwen

A disk drive system has a servo pattern with bursts that are recorded without multiple passes per burst and without trimming, so that the servo pattern bursts have the same width as the data tracks. The servo write steps occur in partial data track pitch (DTP) increments. A magneto-resistive (M-R) head is used to both record the servo pattern and transduce it. In a two-frequency system, relative gain calibration is performed using AGC circuitry to first calibrate one frequency and then the other. The resulting servo position error sensing (PES) signal has improved linearity and is simpler to write.

Compact servo pattern optimized for M-R heads

In a ultra high density, multiple-disk drive, track switches within a cylinder of tracks as well as track switches to tracks on other cylinders both require a movement of the head stack actuator. Track switching latency in such a disk drive is reduced by overlapping pre-movement portions of the track switching process with the data transfer operation of the currently active recording head. In addition, post-movement portions of the track switching process are overlapped with the movement of the heads so that the next selected read/write head may begin a data transfer operation immediately upon arrival at the next track. Further, the pre-movement and post-movement portions of the track-switch process may be overlapped with low displacement movement of the read/write heads relative to the currently active track or the next track.

Method and apparatus for reducing track switch latency in a disk drive

Apparatus and methods for storing predefined information with error correcting code (ECC) in a direct access storage device are provided. Predetermined information is identified and loaded to an ECC generator for customer data to be read and written. The identified predetermined information includes an address for customer data to be read and written. The customer data is written and loaded in parallel to the ECC generator. Then the generated ECC that reflects the pre-loaded predetermined information is written at the end of the written customer data. The customer data and ECC is read and loaded in parallel to the ECC generator. Errors in the predetermined information that is not written to the disk surface, can be detected from the read ECC.

Method and error correcting code (ECC) apparatus for storing predefined

A method and apparatus for write precompensation in a direct access storage device are provided. A data write encoder generates a data signal to be written. A write precompensation delay circuit is coupled to the data encoder for receiving and delaying the data signal. The write precompensation delay circuit includes a first delay path and a second delay path in parallel with the first delay path. The first delay path and the second delay path have different delay values. In one arrangement, both the first delay path and the second delay path include a plurality of delay cells connected together in a chain. The delay cells of the first delay path have a first predetermined delay value and the delay cells of the second delay path have a second predetermined delay value. A ratio of the second predetermined delay value to the first predetermined value is set equal to one of approximately 3/2, 4/3, 5/4, 6/5, or 7/6. In another arrangement, a first delay path includes a plurality of delay cells connected together in a chain and a plurality of delay cells connected in parallel provide multiple parallel delay paths.

Selectable write precompensation in a direct access storage device (DASD)

A self servo writing file and method for writing servo patterns in a direct access storage device are provided. First servo information is written on a data storage media at a first crash stop. The transducer heads are moved offset from the written servo information while reading the last written servo information until the detected servo signal equals a predetermined value. Then servo information is written on the data storage media responsive to the detected servo signal equal to the predetermined value. The moving and writing steps are sequentially repeating until a second crash stop is reached. A quad-burst servo amplitude pattern or phase pattern can be used for the servo information. The servo writing method is adapted easily for many different servo options. When the file uses a hybrid servo or sector servo, the other surfaces can be written by duplicating the servo bursts with a high bandwidth servo system of the file. Alternatively, the servo writing steps can be repeated for each of the other surfaces for providing head dependent pitch. Variable track pitch can be provided by selectively varying the predetermined value compared with the detected servo signal.

Self servo writing file

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.

Storage of user defined type file data in corresponding select physical

A method and apparatus are provided for writing servo bursts with compensation for erase bands in a direct access storage device (DASD). A first servo burst is written on the magnetic disk media using a transducer head in the DASD. The transducer head is moved in a first direction and the first written servo burst is trimmed. The transducer head is moved in a second direction opposite the first direction corresponding to the width of an erase band and then a next servo burst is written.

Method and apparatus for writing servo bursts with compensation for

A multipath channel apparatus for a data storage device wherein data is stored on a storage medium and is read from the storage medium by a transducer or for a data communications system wherein data is transmitted to a receiver. A data channel having a plurality of data paths is operatively connected to the transducer to receive data read from the storage medium by the transducer, or operatively connected to receive data demodulated by the receiver or base band data received by the receiver. Preferably, each of the data paths has a differing parameter value. An error checking unit checks customer and redundancy data from each of the data paths. A selecting unit, which is responsive to the error checking unit, selects data from one of the data paths. In a preferred embodiment, the data stored on a storage medium includes a data field and an error correcting code field, and the customer and redundancy data from each of the data paths is checked using a calculated error correcting code sydrome.

Multipath channel apparatus and method using offset parameters to

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. This minimizes the range requirement for the SA, the main purpose of which is to reduce non-repeatable runout.

Method and apparatus for controlling a multiple-stage actuator for a

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.

Method and apparatus for rotary actuator arc compensation correction in

A method and apparatus adaptively controls the bias supply source for magnetoresistive (MR) read heads within a Direct Access Storage Device (DASD) to provide an optimized bias level for the ambient temperature. An optimal bias level for a given ambient temperature is provided in real time by sensing a temperature within a thermal path to the head (e.g., the ambient temperature surrounding the head) and adjusting the bias supply level to the maximum allowable level for that temperature. This adjustable bias level will thereby enhance MR transducer head sensitivity, improve the signal-to-noise ratio, and also reduce errors in reading data from magnetic storage media within the DASD. The maximum allowable bias supply source level is controlled so as to preserve the overall life expectancy of the MR heads.

Circuit and method for optimizing bias supply in a magnetoresistive head

A self servo writing file and method for writing servo patterns in a direct access storage device are provided. First servo information is written on a data storage media at a first crash stop. The transducer heads are moved offset from the written servo information while reading the last written servo information until the detected servo signal equals a predetermined value. Then servo information is written on the data storage media responsive to the detected servo signal equal to the predetermined value. The moving and writing steps are sequentially repeated until a second crash stop is reached. A quad-burst servo amplitude pattern or phase pattern can be used for the servo information. The servo writing method is adapted easily for many different servo options. When the file uses a hybrid servo or sector servo, the other surfaces can be written by duplicating the servo bursts with a high bandwidth servo system of the file. Alternatively, the servo writing steps can be repeated for each of the other surfaces for providing head dependent pitch. Variable track pitch can be provided by selectively varying the predetermined value compared with the detected servo signal.

Self servo writing file using the widest head

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.

Method and apparatus for ramp load and unload

A magnetic head including a shielded MR element which incorporates a low reluctance path between the shields to reduce interference picked up by inductive reading of the shields. The low reluctance path is provided outside a conductive loop of material which includes the MR element and its associated leads. The low reluctance path may include a magnetic short between the two shields.

Magneto-resistive head including a selectively placed low-reluctance

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Rochester, MN, United States of America

Earl Albert Cunningham