Matsushita Electric Industrial Co., Ltd.

Kabushiki Kaisha Toshiba

Toshiba Electronic Devices & Storage Corporation

Quantum Corporation

Maxtor Corporation

Panasonic Corporation

Toshiba Corporation

Matsushita Electric Industrial

Matsushita Electric Co., Ltd.

Kabuhsiki Kaisha Toshiba

Kabushiki Kiasha Toshiba

Richard M Ehrlich

Thorsten Schmidt

Eric R Dunn

Fernando Anibal Zayas

Gary W Calfee

Anton Gerasimov

William R Akin, Jr

James V Wiseman

Siri S Weerasooriya

Gabor Szita

Mine Wonkyung Budiman

David Rutherford

James A Henson

Craig L Tomita

Ara Patapoutian

Takeyori Hara

Kevin Dean Fisher

Brian Kenneth Tanner

Michael D Leis

Stanley H Shepherd

Mathew Power Vea

Annie Mylang Le

Richard T Curran

Hiroshi Sukegawa

Don Brunnett

Yu Sun

Shoichi Aoki

David B Jeppson

Christopher Montgomery Carpenter

Maxim Roth

Andre C Hall

David Jeppson

Jong Ming Lin

Nathan J Hays

Lance D Beazley

Daniel Tchen

Stephen R Kennedy

Kenji Oki

A digital filter completes a portion of digital filter operations performed on a control signal before the control signal has been determined. Calculation delay associated with performing digital filter operations on the control signal can be reduced and stability of the servo control system improved. For a particular servo wedge of a storage disk, an estimated control signal is used to determine a pre-computed first output of a digital filter before an actual control signal for that particular servo wedge has been determined. Then, once the actual control signal for the servo wedge has been determined, an implemented second output of the digital filter is determined based on the pre-computed first output and a difference between the estimated control signal and the actual control signal. The implemented second output of the digital filter is used to control magnetic head position in response to crossing the servo wedge.

Digital-filter engine with pre-compute of output

Non-sequential write commands in a shingled magnetic recording (SMR) drive are efficiently executed using a skip-bypass mode. When certain conditions are detected in the command history of the drive, the drive changes to the skip-bypass mode. In skip-bypass mode, data associated with the write commands are received into memory of the drive and written directly to a new SMR band in a sequential write operation, thereby bypassing storage in a media cache of the SMR drive. Prior to the sequential write operation, data associated with logical block addresses (LBAs) disposed between the LBAs referenced by the non-sequential write commands are read into the memory by a sequential read operation. The data associated with the non-sequential write commands can then be written, along with the data read in the sequential read operation, in a single sequential write operation to the new SMR band.

Shingled magnetic recording drive with efficient skip-sequential writing

A computer-implemented method for preparing a disk for a disk drive for operation includes: writing first and second servo information in a first portion of a servo sector for a track of the disk; writing third and fourth servo information in a second portion of the servo sector; in a single revolution of the disk, reading a first signal associated with the first servo information, a second signal associated with the second servo information, a third signal associated with the third servo information, and a fourth signal associated with the fourth servo information; based on the first signal, the second signal, the third signal, and the fourth signal, determining a repeatable runout value for the servo sector; and storing the repeatable runout value for the servo sector in a location that is accessed during operation and used during the operation as a repeatable runout correction factor for the track.

Fast characterization of media-noise-induced repeatable runout

A seek operation of a first actuator in a multi-actuator drive is modified, so that one or more disturbance-generating portions of the seek operation do not adversely affect operation of a second actuator in the drive. Radial motion of the aggressor actuator is controlled by limiting a slew rate of the first actuator during one or more portions of the seek operation to be less than or equal to a threshold value. Because slew rate of the first actuator is the rate of change of radial acceleration of the aggressor actuator with respect to time, limiting the slew rate of the first actuator prevents or reduces mechanical disturbances caused by jerk associated with motion of the first actuator.

Split actuator drive that limits slew rate of aggressor VCM to reduce victim disturbances

Systems and methods for scheduling the execution of disk access commands in a split-actuator hard disk drive are provided. In some embodiments, while a first actuator of the split actuator is in the process of performing a first disk access command (a victim operation), a second disk access command (an aggressor operation) is selected for and executed by a second actuator of the split actuator. The aggressor operation is selected from a queue of disk access commands for the second actuator, and is selected based on being the disk access command in the queue that can be initiated sooner than any other disk access command in the queue without disturbing the victim operation.

Seek scheduling in a split actuator drive

A method reduces the effect of accelerating/decelerating an 'aggressor actuator' in a multi-actuator drive on a “victim actuator” in the drive. Measurements of fractional-wedge timing-offsets for an aggressor head are used to adjust the aggressor actuator commands that are inputted to a victim disturbance feedforward signal generator when a timing offset exists between the currently-used aggressor head and the aggressor head that was used to measure transfer functions for determining victim feedforward signals. When such a timing offset is equivalent to a specific fraction of the time period separating servo wedges, values of the aggressor actuator commands that are inputted to the victim disturbance feedforward signal generator may be modified based on the specific fraction. Feedforward signals may be modified when a timing offset exists between and the current timing of the currently-used victim head and an original timing of the currently-used victim head.

Split-actuator drive that coordinates fractional-wedge timing of aggressor and victim for effective victim feedforward

In a multi-actuator drive, the effect of moving a first actuator (the so-called 'aggressor actuator') in on a second actuator (the so-called 'victim actuator') is reduced or compensated for. A victim feedforward signal is added to a microactuator control signal of the victim actuator in response to a voice-coil motor (VCM) control signal that is applied to the aggressor actuator. The feedforward signal is configured to compensate for disturbances to the victim microactuator caused by VCM commands provided to the aggressor actuator. The feedforward signal is based on a transfer function that models commands added to the victim microactuator, which is coupled to the head of the victim actuator, as a function of the aggressor VCM control signal applied to the aggressor actuator.

Split-actuator disk drive that uses microactuator feedforward to reduce effects of cross-actuator coupling

A victim feedforward signal is added to a microactuator control signal of the victim actuator in response to a voice-coil motor (VCM) control signal that is applied to the aggressor actuator, where the victim feedforward signal is configured to compensate for disturbances to a victim head caused by assertion of the aggressor VCM control signal. Each aggressor VCM control signal is asserted at a specific time by the aggressor actuator, for example in response to the aggressor head passing over a first servo wedge. A feedforward signal that compensates for the effect of the aggressor VCM control signal is then determined based on the aggressor VCM control signal, stored, and asserted via the victim microactuator at a predetermined time relative to when the aggressor VCM control signal is asserted.

Split-actuator drive that coordinates timing of aggressor and victim for effective victim disturbance-feedforward

In a magnetic recording drive that includes a shingled magnetic recording (SMR) region and a conventional magnetic recording (CMR) region, the quantity of validation data that is stored by the CMR region is reduced. In the magnetic recording drive, verification data stored in the CMR region is invalidated under certain circumstances, including when an SMR band is closed, when an SMR band is indicated by a host to be reused, when an SMR band is indicated to be finished, and when a last data track of an SMR has data stored therein.

Handling of verification data in disk drive cache

In a multi-actuator drive, the effect of moving a first actuator (the so-called 'aggressor actuator') in on a second actuator (the so-called 'victim actuator') is reduced or compensated for. A victim feedforward signal for a particular head of the victim actuator is added to a microactuator control signal of the victim actuator in response to a voice-coil motor (VCM) control signal that is applied to the aggressor actuator. The feedforward signal is configured to compensate for disturbances to the victim microactuator caused by VCM commands provided to the aggressor actuator. The feedforward signal is based on a transfer function that models commands added to the victim microactuator, which is coupled to the particular head of the victim actuator, as a function of the aggressor VCM control signal applied to the aggressor actuator.

In a disk drive, when an off-track error occurs during a sequential disk access operation that spans multiple contiguous data tracks, efficient recovery is performed. In an embodiment, the disk access operation (e.g., reading from or writing to a disk) is attempted for all sectors of the sequential disk access operation. The disk access operation is then attempted again for sectors associated with any off-track errors that occurred during the disk access operation. In another embodiment, when an off-track error occurs during a sequential write operation in a shingled magnetic recording drive, the data originally targeted to be written to a first portion is written to a second portion of the data track that follows the first portion. Since no additional revolutions of the disk are needed for data associated with the sequential write operation to be written to the disk.

Disk drive with efficient handling of off-track events during sequential write

Growing community of inventors

Saratoga, CA, United States of America

Richard M Ehrlich