Western Digital Technologies, Inc.

Kabushiki Kaisha Toshiba

Toshiba Electronic Devices & Storage Corporation

Siri S Weerasooriya

Tehri S Lee

Charles A Park

Brian P Rigney

Edgar D Sheh

Jiangang Liang

Jianbin Nie

Wing Ying

Richard M Ehrlich

Jack M Chue

Yilin Cai

Robert L Cloke

Yakov M Lifchits

Takeyori Hara

Thorsten Schmidt

Lawrence Matthias Bryant

Soo-Choon Kang

Scott A Ottele

Steven C Smith

William W Clawson

Guoxiao Guo

Wei Guo

Jenghung Chen

Jai N Subrahmanyam

Robert J McNab

Duc H Banh

Harry S Hvostov

Hongchao Tim Zhao

Yun Hong

Chaisit Siricharoenchai

Brandon P Smith

Songwut Jomthaisong

Edmund Ooi Huat Lye

Jeng-Yu Wang

Yap Han Ng

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

Aspects of the present disclosure generally relate to storage devices and methods of operating the same. In one aspect, a storage device includes a disk, and a head configured to write data to and read data from the disk. The storage device also includes a controller configured to receive a read command in a host command queue, store the read command in a disk queue, and determine whether the host command queue is full of pending read commands, including the received read command. If the host command queue is full of pending read commands, the controller forces execution of one of the pending read commands.

Disk drive that efficiently handles random mixed-R/W command-streams

A data storage device is disclosed comprising a disk comprising a spiral track, and a head actuated over the disk, wherein the head comprises a read element offset radially from a write element by a reader/writer offset. The spiral track is first read to write a plurality of concentric servo sectors on the disk that define at least one concentric servo track on the disk. The spiral track is second read and the concentric servo sectors are read to measure the reader/writer offset.

Data storage device measuring reader/writer offset by reading spiral track and concentric servo sectors

A data storage device is disclosed comprising a disk surface comprising a first spiral track at least partially overwritten by a second spiral track, and a head actuated over the disk surface based on the second spiral track. The first spiral track comprises a periodic pattern written at a first frequency, and the second spiral track comprises a periodic pattern written at a second frequency different from the first frequency.

Data storage device attenuating interference from first spiral track when reading second spiral track

A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of spiral seed tracks. The head is positioned at a first radial location over the disk, and the head is servoed over the disk in response to the spiral seed tracks starting from the first radial location in order to write a first spiral servo track on the disk. The head is positioned at a second radial location over the disk different from the first radial location, and the head is servoed over the disk in response to the spiral seed tracks starting from the second radial location in order to write a second spiral servo track on the disk.

Disk drive writing radial offset spiral servo tracks by reading spiral seed tracks

A disk drive is disclosed comprising a disk comprising at least one spiral track, a head, and an actuator operable to actuate the head over the disk. A slope of the spiral track is measured at a plurality of radial locations across the disk, and a spiral track error at each radial location is generated based on a difference between the measured slope and a target slope. The head is actuated over the disk based on the spiral track and the spiral track error.

Disk drive measuring spiral track error by measuring a slope of a spiral track across a disk radius

A data storage device is disclosed comprising a disk surface comprising a first spiral track, and a head actuated over the disk surface. While reading the first spiral track on the disk surface, a second spiral track is simultaneously written on the disk surface. In one embodiment, the second spiral track is written in an opposite radial direction as the first spiral track, and in another embodiment the second spiral track is written in the same radial direction as the first spiral track.

Data storage device reading first spiral track while simultaneously writing second spiral track

A disk drive is disclosed comprising a head actuated over a disk, and a ramp near an outer diameter of the disk, wherein the ramp for unloading the head off the disk. The head is positioned at an inner diameter of the disk and then moved toward the ramp in response to a velocity profile. An interval is measured from a beginning of the movement until the head begins unloading onto the ramp, and the velocity profile is adjusted in response to the measured interval.

Disk drive calibrating a velocity profile prior to writing a spiral track

A disk drive is disclosed comprising a head actuated over a disk comprising servo information. A position error signal is generated while executing a first plurality of seek operations to seek the head over a seek length, and first feed-forward compensation values are adapted for a first segment of the seek length using an iterative learning control algorithm based on the position error signal. During a second plurality of seeks, second feed-forward compensation values are adapted for a second segment of the seek length using the iterative learning control algorithm based on the position error signal. The servo control system is operable to execute the second plurality of seek operations using the first feed-forward compensation generated for the first segment of the seek length.

Disk drive adapting feed-forward compensation using iterative learning control over segments of seek length

A disk drive is disclosed comprising a disk surface comprising a radius, a head operable to generate a read signal, and a voice coil motor (VCM) operable to actuate the head over the disk surface. A back electromotive force (BEMF) voltage generated by the VCM is measured. The VCM is controlled to move the head over substantially the entire radius of the disk surface in response to the BEMF voltage, and while moving the head the read signal from the head is processed to detect residual data recorded on the disk surface after erasing the disk surface.

Disk drive performing spiral scan of disk surface to detect residual data

A disk drive is disclosed comprising a first head actuated over a first disk surface comprising servo information, a second head actuated over a second disk surface, and a voice coil motor (VCM) operable to actuate the first and second heads radially over the respective disk surfaces. The first disk surface and the second disk surface are rotated, and the servo information is read from the first disk surface using the first head to generate a read signal. The read signal is processed to generate a control signal applied to the VCM to move the second head radially over the second disk surface while applying an erase signal to the second head in order to erase at least part of the second disk surface.

Disk drive servoing on first disk surface while erasing second disk surface

A disk drive is disclosed comprising a head actuated over a disk surface, the head comprising a fly height actuator for controlling a fly height of the head, and a ramp for parking the head. A ramp procedure is executed by applying a control signal to the fly height actuator to decrease the fly height and receiving a corresponding fly height signal, and detecting whether the head is on the ramp in response to the fly height signal.

Disk drive detecting when head is on ramp

A servo writer is disclosed operable to write servo sectors on a disk to define non-circular servo tracks. The servo writer comprises control circuitry including a servo control system operable to measure a position of a head over the disk to generate a position signal, generate a position error signal (PES) representing a difference between the position signal and a reference signal, process the PES with a servo compensator to generate a control signal, and position the head over the disk in response to the control signal. A disturbance is induced into the servo control system, and while positioning the head over the disk in response to the control signal, a plurality of servo sectors are written on the disk to define a servo track, wherein the disturbance induced into the servo control system causes the servo track to be non-circular relative to a rotation axis of the disk.

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Campbell, CA, United States of America

Siri S Weerasooriya