Western Digital Technologies, Inc.

Kexiu Liu

Orhan Beker

Mingji Lou

David Robison Hall

Jenghung Chen

Kuang Yang Tu

Hiroshi Uchida

Hidehiko Numasato

Shrey Khanna

Naoyuki Kagami

Chun Sei Tsai

Gaku Ikedo

Carl E Barlow

Kuang-Yang Tu

Peng Huang

Toshihisa Kiyonaga

Kenneth T Tabacchi

A data storage device is disclosed comprising a plurality of disk surfaces, a first plurality of heads actuated over a first subset of the disk surfaces by a first actuator, and a second plurality of heads actuated over a second subset of the disk surfaces by a second actuator. A first access command is executed using the first actuator and a second access command is executed using the second actuator. When the first access command finishes before the second access command finishes, a third access command is selected to execute using the first actuator based on a time remaining (To) to finish the second access command, and at least part of the second access command is executed while concurrently executing at least part of the third access command during To

Data storage device seeking multiple actuators to improve performance

A data storage device is disclosed comprising a first plurality of heads actuated over a first subset of disk surfaces by a first actuator, and a second plurality of heads actuated over a second subset of disk surfaces by a second actuator. A plurality of access commands is received, wherein each access command is associated with one of the heads. A scalar is configured for each access command based on at least one of a current radial location of the corresponding head or a target radial location of the corresponding head associated with executing the access command. The access commands are sorted based on the scalars, and one of the access commands is selected for execution based on the sort.

Data storage device sorting access commands based on current or target location of heads

A data storage device is disclosed wherein an elevator actuator is controlled to move a head along an axial dimension toward a first disk surface of a first disk while processing a proximity signal generated by a proximity sensor. A first actuator position is detected when the actuator arm is proximate the first disk surface of the first disk based on the proximity signal.

Calibrating elevator actuator for disk drive

A data storage device comprising a first actuator configured to actuate a first head over a first disk surface, and a second actuator configured to actuate a second head over a second disk surface. A plurality of access commands are received from a host, and a cost metric is computed for executing a seek to execute each access command of the plurality of access commands, wherein the cost metric is based on an access latency of the seek, a power consumption of the seek, and an estimated combined current draw of the first and second actuators during the seek. The access commands are sorted into an execution order based on the cost metrics computed for the access commands.

Data storage device sorting access commands based on peak current for multiple actuators

A data storage device is disclosed comprising a first actuator configured to actuate a first head over a first disk surface, and a second actuator configure to actuate a second head over a second disk surface. A first seek of the first head over the first disk surface is initiated during a first seek time based on a first seek profile. A second seek of the second head over the second disk surface is initiated during a second seek time based on a second seek profile. When the second seek time at least partially overlaps the first seek time and at least the second seek profile is a de-rated seek profile, the second seek profile is adjusted to avoid an overcurrent condition.

Data storage device managing peak current for multiple actuators

A data storage device is disclosed comprising a first voice coil motor (VCM) configured to actuate a first head, and a second VCM configured to actuate a second head. A high priority is assigned to the first VCM and a low priority to the second VCM. A first access command is serviced using the first head by seeking the first VCM using a first high performance seek profile. When seeking the second VCM without seeking the first VCM, a second access command is serviced using the second head using a second high performance seek profile. When concurrently seeking the first VCM and the second VCM, the seeking of the second VCM is with a reduced performance seek profile, wherein the second high performance seek profile decreases a seek time of the second VCM compared to the reduced performance seek profile.

Data storage device seeking multiple voice coil motors using a limited current supply

A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of tracks, wherein at least two of the tracks comprise a thermal asperity. Prior to seeking the head from a first track to a second track, for each of at least two of the thermal asperities a minimum seek delay and a maximum seek delay that will cause the head to miss the thermal asperity are computed, and an allowed seek delay range that will cause the head to miss the thermal asperity is computed. When the undelayed seek will cause the head to hit at least one thermal asperity, the seek is delayed by a seek delay determined based on the minimum seek delays, the maximum seek delays, and the allowed seek delay ranges.

Data storage device delaying seek operation to avoid thermal asperities

A data storage device is disclosed comprising a disk comprising a plurality of tracks, and an actuator configured to actuate a head over the disk. While seeking the head from a first track toward a second track, a velocity of the head over the disk is measured, and a deceleration distance and a deceleration time is generated based on the measured velocity. A coast velocity is generated based on the measured velocity, the deceleration distance, and the deceleration time, and a control signal applied to the actuator is adjusted based on the measured velocity and the coast velocity.

Data storage device dynamically reducing coast velocity during seek to reduce power consumption

A method of operating a disk drive is disclosed, the disk drive comprising a disk comprising a plurality of tracks, and a closed loop servo system comprising a seek servo loop and a settle servo loop for actuating the head over the disk, the settle servo loop comprising a feed-forward compensator. The seek servo loop seeks the head toward a target track, and when the head approaches the target track a state trajectory of the feed-forward compensator is initialized with an initial value in response to a measured state of the servo system. The settle servo loop then settles the head on the target track in response to a feed-forward compensation generated by the feed-forward compensator.

Disk drive employing model-based feed-forward compensation during seek settling

A method of operating a disk drive is disclosed wherein the disk drive comprises a disk comprising a plurality of tracks, a head, and a closed loop servo system comprising a seek servo loop and a settle servo loop for actuating the head over the disk. When the head approaches a target track during a seek operation, the settle servo loop is enabled wherein a feedback control signal is generated based on a measured state of the servo system. The feedback control signal is adjusted with a feed-forward compensation. A phase shift between the measured state of the servo system and a corresponding estimated state of the servo system is compensated. The head is settled on the target track in response to the feed-forward compensation.

Disk drive employing feed-forward compensation and phase shift compensation during seek settling

A data storage device is disclosed comprising a disk comprising a plurality of tracks, a head, and an actuator configured to actuate the head over the disk. An adjusted seek time is determined to seek the head from a first track to a second track, and an adjusted coast velocity and an adjusted coast time of the seek is determined based on the adjusted seek time and a power consumption of the seek when a driving current applied to the actuator is substantially constant during at least one of an acceleration time and a deceleration time of the seek.

Data storage device reducing seek power consumption

A disk drive is disclosed wherein a radial offset is measured between a first head and a second head at a plurality of points along a circumference of a corresponding first and second disk surface to generate a first plurality of radial offsets. A first radial offset is determined and a second radial offset is determined based on the first plurality of radial offsets, wherein the first radial offset corresponds to approximately a maximum in the first plurality of radial offsets and the second radial offset corresponds to approximately a minimum in the first plurality of radial offsets. A plurality of access commands are stored in a command queue, and a rotational position optimization (RPO) algorithm is executed to select a next access command to execute from the command queue, wherein the RPO algorithm is responsive to the first and second radial offsets.

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Foothill Ranch, CA, United States of America

Kexiu Liu