Western Digital Technologies, Inc.

Other

University of California

Wei Xi

Jianguo Zhou

Guoxiao Guo

Young-Hoon Kim

Kuang-Yang Tu

Jun Xu

Jie Yu

Xu Qi Chen

Alain Chahwan

Dean Mitcham Jenkins

Lei Zhang

Eric S Bjornson

Sanghoon Chu

Michael Troy Nicholls

David W Chew

Jie Wan

Yuanyuan Zhao

Minghui Zheng

Ling Chih Wei

Orhan Beker

Min Chen

Abhishek Dhanda

Yanan Huang

Hien T Chu

Shuyu Cao

Grant C Mackey

Shan Tang

Masayoshi Tomizuka

Jianyi Wang

Danny J Kastler

Nathan J Santee

Hui Li

Junpeng Niu

Jern Khang Tan

Xiaotian Xu

Wenlin Zhang

Shreekant Gayaka

Teddy T Chen

Jianjun Li

Haiming Wang

Systems and methods are disclosed for providing secure access to a data storage device. A user may move the data storage device (e.g., wave, twist, etc.). The data storage device may determine whether the motions valid and may allow access to the data storage device (e.g., to non-volatile memory of the data storage device) when the motions are valid.

Data storage device with secure access based on motions of the data storage device

Systems and methods are disclosed for providing secure access to a data storage device. A user may provide tap inputs, such as taps or knocks, on an enclosure of the data storage device. The data storage device may determine whether the tap inputs are valid and may allow access to the data storage device (e.g., to non-volatile memory of the data storage device) when the tap inputs are valid.

Data storage device with secure access based on tap inputs

Systems and methods are disclosed for accessing data on a storage system. An apparatus, such as a data storage device or a computing device, may include a memory configured to store data. The apparatus is configured to determine an importance level for a file to be stored in the storage system. The data storage system includes one or more private storage clouds and one or more public storage clouds. The apparatus is also configured to generate a set of recovery data chunks based on the file and the importance level. The apparatus is further configured to store the set of recovery data chunks in the set of public storage clouds. The apparatus is further configured to store at least a portion of the file in the private storage cloud.

Hybrid data storage system with private storage cloud and public storage cloud

An apparatus includes: an adaptive declustered RAID array configured of data storage devices (DSDs), the DSDs comprise data chunks allocated as data, a local parity, or a global parity; and a controller configured to generate a reliability indicator reflective of a reliability status of at least a portion of the adaptive declustered RAID array for reallocating the data chunks by dynamically increasing or decreasing the data chunks allocated as the local parity, the global parity, or a combination thereof.

Electronic system with declustered data protection by parity based on reliability and method of operation thereof

Systems and methods are disclosed for accessing data on a storage system. An apparatus, such as a data storage device or a computing device, may include a memory configured to store data. The apparatus is configured to receive a request for a file stored in a storage system. The storage system includes a private storage cloud and a set of public storage clouds. The apparatus is also configured to determine whether the file is retrievable from the set of public storage clouds. If the file is retrievable from the set of public storage clouds the apparatus may determine whether access to the set of public storage clouds is faster than access to the private storage cloud and may retrieve the file from one or more of the private storage cloud and the set of public storage clouds.

Write commands are received for a Data Storage Device (DSD) to store write data in a plurality of corresponding write locations on at least one disk of the DSD. At least a portion of the write data is cached in at least one Media Based Cache (MBC) region of the at least one disk based on a write cache policy for determining which write data is eligible for caching in the at least one MBC region. The at least one MBC region is used to cache data to be stored in other locations on the at least one disk. During an active time period when host commands are performed on the at least one disk, a portion of an I/O bandwidth for performing commands is used to copy the at least a portion of the write data to corresponding write locations of the plurality of corresponding write locations.

Media based cache for data storage device

A data storage device includes a disk, a head, a microactuator, a coarse actuator, and a servo controller. The microactuator is configured to position the head relative to the disk. The coarse actuator is configured to position the microactuator relative to the disk. The servo controller is configured to generate an adjusted position error signal based on a position error signal and an estimated microactuator position signal. The servo controller is also configured to filter the adjusted position error signal with a shaping filter to generate a filtered position error signal, and to provide sliding mode control of the coarse actuator based at least partially on the filtered position error signal.

Data storage devices and methods with frequency-shaped sliding mode control

A data storage device is disclosed comprising a spindle motor configured to rotate a disk, wherein the spindle motor comprises a plurality of windings, and a head actuated over the disk. The windings of the spindle motor are commutated based on a commutation sequence while applying a periodic driving voltage to each winding. During a seek operation to seek the head a seek length, an amplitude of the periodic driving voltage is adjusted according to a driving profile corresponding to the seek length, wherein the driving profile compensates for a power disturbance during the seek operation.

Data storage device employing spindle motor driving profile during seek to improve power performance

A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of tracks defined by servo sectors, wherein each servo sector comprises a plurality of servo bursts and the servo sectors define a plurality of servo wedges. A first write operation is executed to a first track and a first absolute position for the head is generated corresponding to a first servo wedge. A second write operation is executed to a second track and a second absolute position for the head is generated corresponding to the first servo wedge. An off-track write condition is detected when executing the second write operation based on the first absolute position and the second absolute position. The first absolute position comprises a track address of the first track and a position error measurement based on the servo bursts in the first servo wedge.

Data storage device saving absolute position at each servo wedge for previous write operations

A data storage device is disclosed comprising a head actuated over a disk comprising tracks defined by servo sectors. A location of the head is generated based on the servo sectors, and a position error signal (PES) representing a difference between a target location for the head and the measured location for the head is generated. An actuator control signal (ACS) is generated in response to the PES, a disturbance compensation signal (DCS) is generated based on the PES and the ACS, and the DCS is filtered with a disturbance observer filter. The DCS is filtered with a plurality of band-pass filters, and an output of one of the band-pass filters is filtered with a peak detection filter configured to detect a peak frequency corresponding to a peak in a frequency response of the band-pass filter, wherein the disturbance observer filter is adjusted based on the peak frequency.

Data storage device on-line adapting disturbance observer filter

A data storage device is disclosed comprising a first disk surface comprising servo data defining servo tracks at a first radial density, a first head, and a voice coil motor (VCM) configured to actuate the first head over the first disk surface using a servo control system. A load operation is executed to load the first head over the first disk surface, and a back electromotive force (BEMF) voltage generated by the VCM during the load operation is evaluated to generate an estimated distance traveled. The servo data on the first disk surface is detected, and an initial servo track during the load operation based on the detected servo data to generate a measured distance traveled. A gain of the servo control system is configured based on the estimated distance traveled and the measured distance traveled.

Data storage device configuring a gain of a servo control system for actuating a head over a disk

A data storage device is disclosed comprising a microactuator configured to actuate a head over a disk. A control signal applied to the microactuator is generated based on an input sequence u(k). A Preisach bit map bis updated based on the input sequence u(k), wherein the Preisach bit map bcorresponds to a Preisach plane modeling a hysteretic response of the microactuator. A current compensation value yis generated based on an update value generated based on: where hrepresents a slice of the Preisach plane and {circumflex over (b)}is an update bit map based on at least part of the Preisach bit map b. The current input uand the current compensation value yare combined to generate the control signal applied to the microactuator.

Data storage device compensating for hysteretic response of microactuator

A disk drive is disclosed comprising a head, a disk surface comprising servo information, and a dual stage actuator (DSA) servo loop comprising a voice coil motor (VCM) servo loop comprising a VCM and a microactuator servo loop comprising a microactuator operable to actuate the head over the disk surface. A position error signal (PES) is generated based on the servo information, and a first control signal is generated based on the PES. The first control signal is adjusted based on a function of the first control signal to generate a second control signal that compensates for a gain variation of the microactuator, and the microactuator is controlled based on the second control signal.

Disk drive compensating for microactuator gain variations

A data storage device is disclosed comprising a head actuated over a disk and a vibration detector configured to generate a vibration signal in response to a vibration affecting the data storage device. A timing loop is configured to generate a disk-locked clock substantially synchronized to a rotation frequency of the disk. An adaptation control signal is generated based on the vibration signal and an error signal of the timing loop. An adaptive filter is adapted based on the adaptation control signal, wherein the adaptive filter filters the vibration signal to generate feed-forward compensation values. The feed-forward compensation values are applied to the timing loop to compensate for the vibration.

Data storage device employing adaptive feed-forward control in timing loop to compensate for vibration

A disk drive is disclosed comprising a servo control system operable to actuate a head over a disk. A sensor signal is filtered with a first filter comprising a frequency response, and the filtered sensor signal is filtered to generate a compensated sensor signal. An error signal is filtered with a second filter comprising the frequency response, and an adaptation control signal is generated based on the compensated sensor signal and the filtered error signal. An adaptive filter is adapted in response to the adaptation control signal, wherein the adaptive filter filters the sensor signal to generate feed-forward compensation values. The feed-forward compensation values are applied to the servo control system to compensate for the disturbance. A disturbance signal that represents the disturbance is generated, and the frequency response of the first and second filters is optimized based on the sensor signal and the disturbance signal.

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Mission Viejo, CA, United States of America

Wei Xi