Abstract: A data storage device is disclosed comprising a head actuated over a disk, wherein the head comprises a spin torque oscillator (STO). A first bias signal is applied to the STO during a first interval preceding a write operation to write data to the disk, wherein the first bias signal causes the STO to protrude toward the disk. After the first interval, a second bias signal is applied to the STO during a second interval spanning at least part of the write operation, wherein an amplitude of the first bias signal is in the range of 1.1 to 1.5 times an amplitude of the second bias signal.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of tracks defined by a plurality of servo sectors. An estimated track ID is generated and a plurality of proximate track IDs is generated having values proximate the estimated track ID. A set of Gray codes is generated each corresponding to the estimated track ID and the proximate track IDs, wherein each Gray code in the set of Gray codes comprises N bits, and M bits out of a high order of the N bits comprise the same value. A recorded Gray code is detected in a first servo sector to generate a detected Gray code, and an error in the detected Gray code is corrected by inverting at least one bit in the detected Gray code comprising a value that is different from the value of the corresponding bit in the M bits.

Abstract: A disk drive is disclosed comprising a disk comprising a plurality of servo sectors defining a plurality of servo tracks. The servo tracks form a plurality of servo zones, where a servo data rate of servo sectors in a first servo zone is different than a servo data rate of servo sectors in a second servo zone. A servo control system servos a head over the disk. An estimated servo state of a servo control system is generated, and when the head crosses from a first servo zone to a second servo zone, the estimated servo state is adjusted to compensate for a transient in a circumferential distance between a servo sector in the first servo zone and a servo sector in the second servo zone.

Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of tracks defined by a plurality of servo sectors. An estimated track ID is generated and a plurality of proximate track IDs is generated having values proximate the estimated track ID. A set of Gray codes is generated each corresponding to the estimated track ID and the proximate track IDs, wherein each Gray code in the set of Gray codes comprises N bits, and M bits out of a high order of the N bits comprise the same value. A recorded Gray code is detected in a first servo sector to generate a detected Gray code, and an error in the detected Gray code is corrected by inverting at least one bit in the detected Gray code comprising a value that is different from the value of the corresponding bit in the M bits.

Abstract: A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of servo tracks defined by servo bursts. A number of burst correction values are generated by reading at least one of the servo bursts at a number of different radial locations across the disk. The burst correction values are filtered to generate filtered burst correction values, and the filtered burst correction values are downsampled to generate downsampled burst correction values. The downsampled burst correction values are written to the disk, and the head is servoed over the disk by reading the downsampled burst correction values from the disk.

Abstract: A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of servo tracks defined by servo bursts. The head is positioned at a first radial location over the disk and a first burst correction value is generated by reading at least one of the servo bursts. The head is positioned at a second radial location over the disk and a second burst correction value is generated by reading at least one of the servo bursts. The head is positioned at a third radial location over the disk and the first burst correction value and the second burst correction value are written at the third radial location. The head is servoed over the disk by reading the first and second burst correction values.

Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of tracks defined by servo sectors forming a plurality of full wedges and a plurality of mini wedges. The wedge ID field of a servo sector forming one of the full wedges is offset from a beginning of a sync mark by a first offset, and the wedge ID field of a servo sector forming one of the mini wedges is offset from the beginning of the sync mark by a second offset equal to the first offset. A first servo sector is read from the disk to generate a read signal, the read signal is demodulated to detect the wedge ID of the first servo sector, and the detected wedge ID is evaluated to determine whether the first servo sector forms one of the mini wedges.

Abstract: A disk drive is disclosed comprising a timing loop configured to generate a clock synchronized to a rotation of a disk and a servo loop configured to control an actuator to actuate a head over the disk. A timing signal generated by the timing loop is filtered with a pre-compensation filter (PCF) comprising an inverse transfer function from a delta in a rotation velocity of the disk (??) due to a vibration affecting the disk drive to the timing signal, and the actuator is controlled to actuate the head over the disk based on an output of the PCF.

Abstract: 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.

Abstract: A data storage device is disclosed comprising a disk comprising data, and a head actuated over the disk. A timing signal is generated by reading the data from the disk, and a frequency generator is adjusted based on the timing signal to generate a disk locked clock substantially synchronized to a rotation speed of the disk. A free fall condition is detected based on the timing signal, and when the free fall condition is detected the head is parked.

Abstract: A data storage device is disclosed comprising a disk surface comprising a plurality of tracks, wherein each track comprises a plurality of data sectors and a plurality of servo sectors. The data storage device further comprises a head actuated over the disk surface, the head comprising at least one read element and at least one write element. Control circuitry is configured to use the head to write to a first data sector on the disk surface while simultaneously reading from a first servo sector on the disk surface.

Abstract: A disk drive is disclosed comprising a disk comprising a plurality of servo tracks defined by servo sectors recorded around the circumference of the disk at a servo sampling frequency, and a servo control system operable to actuate a head over the disk by generating a control signal applied to an actuator. A first sinusoid is injected into the servo control system and a first DC component (dc1) is measured in the control signal. A second sinusoid is injected into the servo control system and a second DC component (dc2) is measured in the control signal, wherein the second sinusoid comprises a phase offset from the first sinusoid. A resonance mode of the servo control system is measured based on dc1 and dc2.

Abstract: A disk drive is disclosed comprising a disk having a plurality of data tracks defined by servo sectors, where each data track comprises a plurality of data sectors, and each servo sector comprises a servo preamble and servo data. The disk drive further comprises a head comprising a read element and a write element, and a servo read channel comprising an analog front end and a timing recovery circuit. During an access operation, data preceding the servo preamble of a first servo sector in the first data track is read in order to initialize the analog front end of the servo read channel. At least part of the servo preamble is read to initialize the timing recovery circuit of the servo read channel, and at least part of the servo data of the servo sector is read using the timing recovery circuit.

Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of servo tracks defined by full sectors and intervening short servo sectors, where each full servo sector comprises a preamble, a sync mark, and servo bursts, and each short servo sector comprises a reference pattern and servo bursts. A first phase error is generated based on the sync mark in a first full servo sector, and a disk locked clock is adjusted in response to the first phase error. A second phase error is generated based on the reference pattern in a first short servo sector, and the second phase error is processed to determine whether the disk locked clock slipped a cycle before the head reaching the first short servo sector.