International Business Machines Corporation

Dana H Brown

Earl Albert Cunningham

Hal Hjalmar Ottesen

Richard Greenberg

Kevin Jack Erickson

Thomas C Christensen

Wayne A Rogelstad

Zine-Eddine Boutaghou

Mark David Hagen

Timothy Joseph Chainer

Gordon James Smith

John Charles Purkett

John Jeffrey Stephenson

Thomas W Glaser

Peter M Herman

Wayne J Sohn

Russell A Billings

Daniel L Good

Richard H Estry

Dean C Palmer

A phase modulated servo method and apparatus provide acceptable position linearity for servo positioning with a narrow transducer head in a disk file. The disk file includes at least one disk mounted for rotation about an axis and the disk has at least one disk surface for storing data and has at least one transducer mounted for movement across the disk surface for writing to and for reading data and servo patterns from the disk surface. The transducer includes a read element and a write element. The read element has a width less than the write element and the read element width is greater than &frac13; of a data cylinder and less than &frac12; of a data cylinder. A servo pattern is written on the data disk surface having a track pitch of less than &frac12; of a data cylinder and the servo pattern repeats in a selected binary number of data cylinders.

Method and apparatus for servo positioning in a direct access storage device with a transducer read element width greater than &frac13; and less than &frac12; width of a data cylinder

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 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

In a disk drive in which a head disk assembly includes a slider suspension member and a parking ramp on which the suspension member rests when the disk drive is not operating, stiction forces between the suspension member and the parking ramp are overcome by applying simultaneously to the suspension member a dither in the form of rocking micromotion, and a bias force to move the suspension member at a low velocity required for loading a slider onto a disk without damage to the slider/disk interface.

Velocity control of head load/unload mechanism in a disk drive using

A direct access storage device may handle various disk drive management functions without contemporaneous host computer involvement by buffering commands for the management functions in controller memory. The commands may be read into controller memory from the disk drive on power up or programmed by the host computer. Initially the commands are treated as processes in a blocked state. Operating statistics kept by a supervisor program for the controller are monitored by an event handler, which moves processes to a ready to run state upon occurrence of specified conditions. A dispatcher then moves commands into the direct access storage controller for execution and subsequent return to blocked status.

System for automatic buffering of commands for DASD units

An apparatus and method for correcting for track misregistration when a slider or head assembly contains a separate read element and write element. The offset is determined at a first position and at a second position of the actuator arm assembly. From these offsets a constant and a multiplier are determined for determining an offset as a function of the cylinder location. Also disclosed is a method and apparatus for minimizing distance traveled to prevent misregistration when repositioning between the read element and a write element. The read element is intentionally offset from the write element at an angle so as to minimize the distance traveled across the disk.

Method and apparatus for positioning transducers to correct for read and

A method and apparatus are provided for servo demodulation in a direct access storage device. A readback signal is sensed from at least one disk surface and locations of positive and negative peaks in the sensed readback signal are detected for providing a detected peak signal. A square wave signal having a period variable with distance between detected locations of positive and negative peaks is generated using the detected peak signal and applied to a servo demodulator in the direct access storage device.

Method and apparatus for servo demodulation in a direct access storage

A disk drive stores multimedia data in long spiral data tracks. The tracks on opposite surfaces of the disk spiral in opposite directions, so that a track on one surface can be read as the actuator sweeps in, and a track on the opposite surface can be read as the actuator sweeps out. Because the actuator only follows spiral tracks without performing long seek operations, the actuator motor can be reduced in size and stresses on actuator bearings and other parts are reduced. Additionally, due to reduced disturbances associated with seeks, it is possible to follow tracks more closely and therefore reduce the width of individual tracks. Further cost reductions are accomplished by spinning the disks at a slower speed and reducing the size of the spin motor accordingly. Finally, data density can be increased simply because multimedia data does not require the same low error rate as conventional data. Preferably, a group of disk drives optimized for multimedia data is used to form a video-on-demand system. Compressed, interleaved portions of a video presentation, such as a motion picture, are stored in blocks on the spiral tracks. The drives read the blocks on one spiral track at a time from beginning to end, placing the data from these blocks in a set of buffers corresponding to different short time intervals. Video signals are output from the buffers. Any short time interval of the presentation can be accessed on demand by switching to the appropriate buffer.

Disk storage device with spiral data track and incremental error offsets

A secondary data storage system for a host computer system includes a disk drive system having a device controller, at least a first magnetic disk and a read/write magnetic transducer positionable with respect to a recording surface of each magnetic disk. A write operation exposes data on adjacent tracks to potential damage if an off track condition occurs to the transducer during a write. A method for controlling write operations through the device controller provides backup of data in tracks adjacent to a target track for the write operation prior to the write operation occurring. The method detects occurrence of events resulting in an off track condition of the magnetic transducer relative to a target track. Occurrence of such an event triggers a determination of damage to the contents of tracks adjacent to the target track and restoration of those tracks. Write operations to the target track are blocked until shock events discontinue.

System and method for preventing direct access data storage system data

Apparatus and method are provided for servo signal demodulation using a servo processor and a partial-response maximum-likelihood (PRML) data channel in a disk file. A servo burst timing window is identified. Then a plurality of digital samples are detected with the PRML data channel responsive to identifying the servo burst timing window. Sequential sets of the detected digital samples are accumulated by the PRML data channel and transmitted to the servo processor. The digital samples are processed by the servo processor for providing servo phase information that is used to provide servo position information.

Digital servo signal demodulation method and apparatus utilizing a

A laser (10) provides an output beam to an interferometer (12). A portion of the output beam is directed by a beamsplitter to a receiver (18) as a reference beam while the remaining portion of the output beam passes through the beamsplitter and impinges on a plane mirror reflective surface (14a) mounted upon or integrally formed with or upon a surface of a body of interest, such as rotary actuator or arm (14). The arm has a fixed center of rotation O and rotates through an angular range indicated by theta-max. Phi is the angle of incidence of the laser beam with the arm in its original position when theta equals zero. .vertline.OC.vertline. and .vertline.CD.vertline. are distances which locate the intersection point between the arm and the laser beam relative to the center of rotation O when theta equals zero. A corner cube (16) is located at a convergence plane and returns all reflected beams back to the plane mirror and hence to the receiver via the interferometer. The interferometer and receiver operate to provide a determination of the position of the arm relative to a reference position, the determined position being used to cause a servo track or tracks to be written upon a medium at a desired position.

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Rochester, MN, United States of America

Dana H Brown