Abstract: The present disclosure generally relates to aborting a command efficiently using the host memory buffer (HMB). The command contains pointers that direct the data storage device to various locations on the data storage device where relevant content is located. Once the abort command is received, the content of the host pointers stored in the data storage device RAM are changed to point to the HMB. The data storage device then waits until any already started transactions over the interface bus that are associated with the command have been completed. Thereafter, a failure completion command is posted to the host device.

Abstract: Various illustrative aspects are directed to a data storage device comprising one or more disks, an actuator arm assembly comprising a voice coil motor (VCM), the VCM configured to operate in a first mode and a second, different mode, wherein the first mode corresponds to at least a first and a second setting, and a control circuitry configured to cause the VCM to seek towards a target track in the first mode using the first setting for a first duration, control transition of the VCM from the first to the second setting in the first mode, cause the VCM to seek towards the target track using the second setting for a second duration, and control transition of the VCM from the first to a second mode, wherein controlling the transitioning comprises seeking the VCM toward the target track in the second mode for a third duration.

Abstract: According to one embodiment, a magnetic disk device comprises an actuator, a controller that controls the actuator, a loop shaping filter connected in parallel with the controller, the loop shaping filter having a parameter for suppressing a rotation asynchronous disturbance affecting the actuator, the parameter of the loop shaping filter being determined using a transfer function from an output of the loop shaping filter to before an input of the rotation asynchronous disturbance, and a notch filter that suppresses mechanical resonance of the actuator.

Abstract: 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.

Abstract: According to an embodiment, in a disk device, a first actuator moves a first head with respect to a first surface of a first disk. A controller controls positioning of the first head via the first actuator and controls a write operation to the first disk by the first head. The controller acquires information regarding a state of a vibration source, changes a value of a coefficient for estimating a predicted position of the first head according to the information regarding the state of the vibration source, estimates a predicted position of the first head with the value of the coefficient changed, performs a write operation by the first head in a case where the predicted position estimated is equal to or less than a threshold, and prohibits the write operation by the first head in a case where the predicted position estimated exceeds the threshold.

Abstract: Techniques for generating action recommendations for a data tape system based on a media drive calibration are disclosed. A system receives a request to perform an operation including an exchange between a data tape and a media drive. If the system determines that the operation is a data tape validation operation, the system determines whether the media drive is calibrated. If the calibration value of the media drive does not meet a threshold, the system performs a calibration procedure. The system may calibrate the media drive or replace the media drive with a calibrated media drive. The system performs the validation operation. Based on a validation result, a data tape quality value, and the media drive calibration value, the system generates a recommended action for a data tape.

Abstract: An amplification interface includes first and second differential input terminals, first and second differential output terminals providing first and second output voltages defining a differential output signal, and first and second analog integrators coupled between the first and second differential input terminals and the first and second differential output terminals, the first and second analog integrators being resettable by a reset signal. A control circuit generates the reset signal such that the first and second analog integrators are periodically reset during a reset interval and activated during a measurement interval, receives a control signal indicative of offsets in the measurement sensor current and the reference sensor current, and generates a drive signal as a function of the control signal. First and second current generators coupled first and second compensation circuits to the first and second differential input terminals as a function of a drive signal.

Abstract: According to one embodiment, a first storage area and a second storage area in which a plurality of tracks are set are provided in a radial direction of a magnetic disk. A plurality of post codes corresponding to the second storage area is stored in the first storage area. A controller controls first processing of reading a plurality of post codes from the first storage area and writing the plurality of read post codes in servo area of the second storage area. In the first processing, the controller controls both second processing and third processing in a state where a write head is located on a first track. The second processing is processing of writing a post code among the plurality of read post codes in a servo area. The third processing is processing of writing user data in a data area or reading user data from a data area.

Abstract: According to one embodiment, a magnetic disk device includes a disk, a head that has a write head that writes data to the disk and a read head that reads data from the disk, and a controller that changes an offset amount during read processing according to a vibration applied by a disturbance.

Abstract: According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head configured to write data on the magnetic disk, an assist section configured to assist, when the magnetic head writes data on the magnetic disk, write of the data by utilizing an assist element, a voltage control section configured to control a voltage to be applied to the assist element, and a positioning control section configured to carry out positioning of the magnetic head relatively to the magnetic disk on the basis of servo data and acquire positional error data of the magnetic head positioned on the basis of the servo data. The voltage control section adjusts the voltage to be applied to the assist element on the basis of the positional error data.

Abstract: A torque ripple and a position error caused by an offset error of the current sensor affects an electrical angle frequency of a motor. In an apparatus of the present disclosure, a computation device executes a power spectrum computing process when a three-phase alternating current motor is at a constant speed, and a value obtained by subtracting a position command value from a position detected by a position detector is fast Fourier transformed, to compute a power spectrum of a position error signal at the electrical angle frequency. Then, the computation device executes an offset correction computing process, to evaluate the power spectrum and to update an offset correction amount. By repeatedly executing these processes when the three-phase alternating current motor is driven at a constant speed, the torque ripple and position error caused by the offset error are reduced.

Abstract: A magnetoresistive memory device includes a magnetic tunnel junction comprising a free layer, a reference layer, and an insulating tunnel barrier layer located between the free layer and the reference layer, a perpendicular magnetic anisotropy (PMA) ferromagnetic layer that is vertically spaced from the free layer, an electrically conductive, non-magnetic interlayer exchange coupling layer located between the free layer and the PMA ferromagnetic layer. The magnetoresistive memory device is a hybrid magnetoresistive memory device which is programmed by a combination of a spin-torque transfer effect and a voltage-controlled exchange coupling effect.

Abstract: A data storage circuit includes memory, an error correcting code (ECC) storage circuit, and control circuitry. The memory is configured to store a data value comprising a plurality of fields. Each of the fields is independently writable. The ECC storage circuit is configured to store an ECC value corresponding to the data value. The control circuitry is configured to receive a field value to be written into one of the fields, and store the field value in the one of the fields by writing only the field value to the memory. The control circuitry is also configured to retrieve the ECC value from the ECC storage circuit, compute an updated ECC value based on the ECC value retrieved from the ECC storage circuit and the field value, and store the updated ECC value in the ECC storage circuit.

Abstract: 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.

Abstract: Methods and systems that reduce off-track write retry operations in shingled magnetic recording systems. In one implementation, the method includes writing data to an initial track, determining which side of the initial track is a shingled side, calculating a percentage of position error signal (PES) at a shingled side end of the initial track (PES1) when an off-track write operation occurs, determining whether the PES1 meets a first pre-determined threshold, continue writing data to a second track responsive to determining the PES1 is below a first pre-determined threshold, calculating a percentage of PES at a shingled side end of the second track (PES2), determining whether a combined value of PES1 and PES2 is above a second predetermined threshold to determine a probability value of the initial track being erased, and continue writing to a third track if the combined value is below the second predetermined threshold.

Abstract: A rotary rheometer includes a drive shaft and a dual read head optical encoder that is configured to measure angular displacement or angular velocity of the drive shaft.

Abstract: The disclosed technology includes methods and systems that reduce off-track write retry operations in shingled magnetic recording systems. In one implementation, the method includes writing data to an initial track, determining which side of the initial track is a shingled side, calculating a percentage of position error signal (PES) at a shingled side end of the initial track (PES1) when an off-track write operation occurs, determining whether the PES1 meets a first pre-determined threshold, continue writing data to a second track responsive to determining the PES1 is below a first pre-determined threshold, calculating a percentage of PES at a shingled side end of the second track (PES2), determining whether a combined value of PES1 and PES2 is above a second predetermined threshold to determine a probability value of the initial track being erased, and continue writing to a third track if the combined value is below the second predetermined threshold.

Abstract: A dual-stage servo system of a disk drive includes a first fine positioning servo system with a first microactuator that independently controls the position of a first read/write head over a first recording surface and a second fine positioning servo system with a second microactuator that independently controls the position of a second read/write head over a second recording surface. The first microactuator accesses a first data stripe while the second fine positioning servo system simultaneously accesses a second data stripe. Data can be transferred to or from the first and second data stripes simultaneously.

Abstract: A motor drive apparatus includes a drive unit to supply motor coils with sinusoidal drive signals, a signal output unit outputs signals that change with rotation of a rotor, and a control unit. The control unit acquires first information relating to the sinusoidal drive signals at a timing of change of a corresponding one of the output signals in a case where there is no follow-up delay of the rotor relative to the drive signals. When the corresponding one of the output signals is changed, the control unit acquires second information relating to the sinusoidal drive signals at a timing of change of the corresponding one of the output signals in a case where there is a follow-up delay of the rotor relative to the drive signals. The control unit corrects the follow-up delay of the rotor based on a determined difference between the first and second information.

Abstract: Apparatus and method for disturbance rejection in a control system. In some embodiments, a controller is adapted to position a control object. A disturbance observer generates a disturbance compensation value which is applied to reduce position error resulting from application of mechanical disturbance to the control object. The disturbance observer includes an adaptive filter with at least one dead zone providing a pass-through response with a scalar gain of less than one.

Abstract: A data storage device is disclosed comprising a voice coil motor (VCM) and a secondary actuator configured to actuate a head over a disk. A position error signal (PES) is generated based on servo data recorded on the disk, and a first control signal is generated based on the PES. The PES is adjusted based on the first control signal to generate a first adjusted PES, and a second control signal is generated based on the first adjusted PES. A secondary actuator control signal is generated based on the first control signal and the second control signal, wherein the secondary actuator control signal is applied to the secondary actuator. The first adjusted PES is adjusted based on the second control signal to generate a second adjusted PES, and a VCM control signal is generated based on the second adjusted PES, wherein the VCM control signal is applied to the VCM.

Abstract: This disclosure describes apparatuses and techniques for multi-channel servo demodulation. Multiple servo demodulation channels enable additional information to be obtained during the self-servo writing process, such as relative positions of multiple read heads and tracking of multiple servo patterns. This additional information enhances accuracy for self-servo writing and can lead to higher recording densities in media drives, and thus more storage with little or no additional cost.

Abstract: According to one embodiment, a magnetic element includes a first stacked unit and a third ferromagnetic layer. The first stacked unit includes first and second ferromagnetic layers, and a first non-magnetic layer. The first ferromagnetic layer has a first magnetization. The second ferromagnetic layer is separated from the first ferromagnetic layer in a first direction, and has a second magnetization. The first non-magnetic layer is provided between the first and second ferromagnetic layers. The third ferromagnetic layer is stacked with the first stacked unit in the first direction, and has a third magnetization. 2?NzMs is not less than 0.9 times of a magnetic resonance frequency (Hz) of the third ferromagnetic layer, when the second magnetization is Ms (emu/cc), a demagnetizing coefficient of the second ferromagnetic layer is Nz, and a gyro magnetic constant is ? (Hz/Oe).

Abstract: To suppress a decline in the control accuracy of an applied voltage associated with an increase in quantum noise, and to increase the control accuracy of a motor speed. When generating a driving voltage signal supplied to a motor from a driving command signal, a motor-driving voltage control device reduces the gradation level and performs noise-shaping modulation before performing PWM modulation. Reducing the gradation level allows the degree of gradation of the driving voltage signal to be within the resolution range of the PWM modulation, and thus PWM modulation can be performed even when the driving voltage signal has a high frequency. Noise-shaping modulation reduces the level of quantum noise near the low frequency range by causing the quantum noise due to digitization, included in the driving voltage signal, to be biased toward the high frequency range side.

Abstract: Implementations disclosed herein provide a method comprising applying voltage to a read head during an unload state, detecting characteristic read head data, and storing the detected characteristic read head data in a buffer. In another implementation, the method further comprises performing a read retry operation in response to a read failure, reading the detected characteristic read head data from the buffer, determining if the detected characteristic read head data meets a threshold for a first predetermined criterion, performing a correction operation if the threshold for the first the first predetermined criterion is met, determining whether a media sector is read successfully, and ending the read retry operation if the media sector is read successfully.

Abstract: According to one embodiment, a disc device outputs a first signal for canceling out a first disturbance at a predetermined frequency of a position error, outputs a second signal which gain or phase of the first signal are changed, and corrects an operation amount or the position error by using the second signal.

Abstract: One example includes an amplifier system. The system includes a gain stage configured to conduct a gain current in response to an input voltage. The system also includes a current limit stage coupled to the gain stage and being configured to one of source and sink the gain current and to define a limit amplitude of the gain current during a current limit condition. The system further includes an output stage coupled to the gain stage and configured to conduct an output current through an output node in response to the gain current, the output current having a maximum amplitude during the current limit condition that is proportional to the limit amplitude.

Abstract: According to one embodiment, a servo writing method for a magnetic disk apparatus that includes a magnetic disk and a head is provided. The method rotates the magnetic disk, derives a path obtained by adding a second specifying value to a first specifying value, the first specifying value corresponding to a separation distance from a rotation center of the magnetic disk, the second specifying value periodically displacing the separation distance in a radial direction synchronously with a rotation angle of the magnetic disk, the second specifying value being a value in which the separation distances at a start point and an end point of one rotation of the magnetic disk coincide, and, while causing the head to follow the path, writes servo information onto the magnetic disk with the head.

Abstract: A disk apparatus control device including an A/D converting section that samples an analog current amount signal indicating a current amount for a drive current of a motor that moves a head for accessing a storage disk of a disk apparatus, and converts the analog current amount signal into a digital current amount signal indicating the current amount. The device can further include a control signal generating section that, according to digital control, generates a digital control signal corresponding to a manipulation amount of the drive current, based on a difference between the current amount indicated by the digital current amount signal and a target value for the current amount of the drive current. Additionally, the device can include a D/A converting section that converts the digital control signal into an analog control signal, and outputs the analog control signal to a drive current generating section that generates the drive current.

Abstract: A method includes issuing write commands to DS storage units regarding encoded data slices. A write command causes a storage unit to store an encoded data slice, but not allow access to the stored encoded data slices. The method includes receiving write acknowledgements from at least some of DS storage units to produce received write acknowledgements. The method includes, when a write threshold number of the received write acknowledgements have been received within a given time frame, issuing commit commands to the DS storage units. A commit command causes the storage unit to allow access to the stored encoded data slice. The method includes, when the write threshold number of the received write acknowledgements have not been received within the given time frame, issuing rollback commands to the DS units. A rollback command causes the storage unit to continue to not allow access to the stored encoded data slice.

Abstract: Systems and methods are disclosed for write fault modulation. In an embodiment, an apparatus may comprise a circuit configured to adjust a write fault value for a data storing system based on a circumferential point of a target data storage location, and write data based on the write fault value. The write fault value may represent an amount of off-track deviation of a data writing system within which data writing operations may be performed. In another embodiment, a memory device may store instructions that cause a processor to perform a method including receiving a write command including write data, determining a write fault threshold for a circumferential point of a target location of the write data, performing, using a transducer, a write operation at the circumferential point based on the write fault threshold, and suspending the write operation when a positional deviation of the transducer exceeds the write fault threshold.

Abstract: 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.

Abstract: According to an embodiment, there is provided a disc device that execute a filtering process to remove one or more resonances from the first signal by the sum of transfer functions, the one or more resonances being included in first transfer characteristics from the first signal transmitted via the first control line to response of the first head, the transfer functions being indicative of resonances included in second transfer characteristics from the first signal transmitted via the second control line to response of the first head.

Abstract: 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.

Abstract: A data storage assembly for cold storage. The data storage assembly includes a circuit board and a plurality of hard disk assemblies (HDA). Each HDA includes a platter and a head assembly to read and write data on the platter. The circuit board includes a processor and a read channel. The processor acts as a hard disk controller for the plurality of HDAs and controls the platters. The processor further manages which HDAs are active at a time and the read channel is shared by the plurality of HDAs.

Abstract: A disk drive is disclosed comprising a disk comprising a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors, and an actuator for actuating a head over the disk in response to an actuator control signal. The servo sectors are read to generate a first sequence of control samples x[k] at a sample frequency corresponding to a frequency of the servo sectors. A hybrid upsample filter is used to upsample by a factor of N the first sequence of control samples x[k] to generate a second sequence of control samples y[ki], wherein the hybrid upsample filter provides a higher phase gain than a zero-order type upsample filter at frequencies less than one kilohertz, and approximately the same attenuation as a first-order type upsample filter around the sample frequency. The actuator control signal is generated in response to the second sequence of control samples y[ki].

Abstract: Systems and methods for improving the accuracy of test measurements involving aggressor tracks written to the disks are provided. One such method involves erasing a circumferential band of a disk, writing a central track on the circumferential band, measuring and storing a first track profile of the central track, writing an aggressor track on each side of the central track at a preselected aggressor track offset from the central track, measuring and storing a track profile of the aggressor tracks at the preselected aggressor track offset, measuring and storing a second track profile of the central track, performing the prior actions exactly n times where n is greater than or equal to 1, determining an estimated distance between the aggressor tracks based on the respective track profiles, determining a selected measurement using the estimated distance between the aggressor tracks, and the first and second track profiles of the central track.

Abstract: Systems and methods are disclosed that implement asymmetrical write fault thresholds. A data storage device may apply a different write fault threshold to each side of a target track, allowing a write head to deviate from a track center more in one direction than in the other direction. In some embodiments, the asymmetrical write fault thresholds may be applied to shingled tracks, allowing a lower write fault threshold to be applied in the direction of previously written shingled tracks, and a higher write fault threshold to be applied in the direction of tracks which are not yet written.

Abstract: A media drive includes a head, a servo signal processing circuit, an actuator and a processor. The head is positioned near a data storage medium, and includes a servo element. The servo signal processing circuit is coupled to the servo element to output a position error signal. The actuator controls a position of the head relative to the data storage medium. The processor communicates with the actuator and the servo signal processing circuit. The processor provides a filtered position error signal to the actuator to compensate for a position displacement between the head and the data storage medium. The filtered position error signal includes a sum of outputs from a first compensation filter and a second compensation filter that is each applied to the position error signal output. The compensation filters attenuate disturbance frequencies that contribute to the position displacement. Each of the compensation filters has a sampling rate relating to the respective disturbance frequency.

Abstract: Systems and methods are disclosed for isolated bands of fractional tracks in data storage devices, particularly devices employing shingled magnetic recording. In one embodiment, a device may comprise a data storage medium including a first data storage area including tracks overlapped in a shingled manner and having a first circumferential portion of a track to store data, a second data storage area, and a guard area disposed between the first data storage area and the second data storage area, the guard area including a second circumferential portion of the track as a partial guard track. In some embodiments, the guard area may include at least one sector in the first circumferential portion of the track, such that at least one sector of the guard area is interposed between data storage sectors of the first data storage area.

Abstract: Systems and methods are provided that may be implemented to provide a mechanical indicator to correlate magnetic disk drive IOP performance with features of mechanical and/or acoustic vibrational frequencies that are generated and captured or sensed outside of the disk drive itself. In one example, disk drive PES data may be collected concurrently with the capture of mechanical and/or acoustic vibrational data at different and progressive locations of vibration source, vibration path and vibration receiver in a disk drive operating environment, e.g., such as for disk drives installed within a server and/or storage chassis enclosure. In such case, PES threshold may be utilized to correlate performance of Drive IOP or drive servo-mechanical performance as a function of measured characteristics of vibration source/s that impart vibration to a disk drive.

Abstract: Methods for measuring media performance associated with adjacent track interference are provided. One such method includes iteratively writing data to a target track for each of a plurality of n frequencies, measuring a first signal amplitude and a first noise for each of the n sectors on the target track, writing an aggressor track pattern proximate the target track, measuring a second signal amplitude and a second noise for each of the n sectors on the target track, calculating a weighted sum for each of the signal amplitude measurements for each of the plurality of n frequencies, and calculating a weighted sum for each of the noise measurements for each of the plurality of n frequencies, and repeating the writing the aggressor track pattern, the measuring the second signal amplitude and the second noise, and calculating the weighted sums for preselected numbers of times.

Abstract: A data storage device may be configured at least with an actuating assembly that has a head-gimbal suspension assembly (HGSA), first pivot point, and second pivot point. The head-gimbal assembly can be constructed and operated with at least first and second transducers aligned along a longitudinal axis of the head-gimbal suspension assembly. A controller may be adopted to manipulate the head-gimbal suspension assembly about at least one of the pivot points in response to a head-gimbal suspension assembly offset misalignment to compensate for such an offset.

Abstract: Techniques for writing data to a buffer region of a magnetic disk are described. In one example, a hard disk drive comprises a magnetic disk comprising a data buffer region including a first zone and a second zone. Data may be written to the magnetic disk using shingled magnetic recording (SMR) and the buffer region may be an exception region (E-region). A hard disk drive may be configured to calculate a position accuracy value associated with a data writing head. The hard disk drive may select one of the zones based on the position accuracy value. Further, a selected zone may have a determined zone format. The hard disk drive may be configured to write data to the selected zone using the determined zone format.

Abstract: A disk drive is disclosed comprising a disk, and a head actuated radially over the disk, wherein the head comprises a read element separated from a write element by a reader/writer gap. A disk-locked clock is synchronized to a rotation of the disk, wherein the disk-locked clock comprises a plurality of clock cycles, and the reader/writer gap spans a first number of the clock cycles comprising an integer of the clock cycles plus a fraction of one of the clock cycles. The fraction of one of the clock cycles is measured when the head is positioned at a first plurality of radial locations across the disk, and a second plurality of radial locations is estimated where the fraction substantially equals a full one of the clock cycles.

Abstract: In one implementation, a method and apparatus is provided for determining an active fly height setting for a transducer head from samples collected from a proximity sensor during less than a single revolution of a disc. Implementations of the method and system use adaptive discrete wavelet transform parameters generated from the collected samples to determine an active fly height setting for a transducer head.

Abstract: A movement control apparatus includes: an actuator that causes a driven body connected to a driving coil to perform reciprocating movement; a signal generation unit that generates a velocity command signal which indicates a target velocity of the driven body; a driving unit that supplies electric current corresponding to a driving signal to the driving coil; a voltage detection unit that detects induced voltage generated in the driving coil, and outputs a voltage signal corresponding to the induced voltage; a signal correction unit that corrects, based on the driving signal and the voltage signal, the voltage signal to adjust a shift of a resistance value from a reference resistance value of the driving coil, thereby generating a velocity signal; and a control unit that generates the driving signal based on the velocity command signal and the velocity signal, and outputs the driving signal to the driving unit.

Abstract: A storage device has a device body and a read/write head for reading and writing data in a data track of a storage medium. An actuator system is mounted on the device body for effecting movement of the read/write head relative to the data track to align the head with the data track. The actuator system has a plurality of degrees of freedom, and a controller controls the actuator system to effect the movement. A body vibration sensor provided on the device body generates a signal indicative of vibration of the body. An actuator vibration sensor generates a signal indicative of vibration of the actuator system. The controller is adapted to process the signals from the sensors to derive a coupling signal indicative of vibration coupling between the degrees of freedom, and to control the actuator system dependent on the coupling signal and the signal from the body vibration sensor.

Abstract: A disk drive is disclosed comprising a head actuated over a disk, wherein data is written to the disk comprising a first periodic pattern, a payload, and a second periodic pattern. The data is first read from the disk to generate a first read signal, and the first read signal is sampled asynchronously to generate first asynchronous signal samples. The first asynchronous signal samples representing the first periodic pattern are processed to measure a first phase, and the first asynchronous signal samples representing the second periodic pattern are processed to measure a second phase. A first phase error is generated based on a difference between the first phase and the second phase. The first asynchronous signal samples representing the payload are adjusted in response to the first phase error to generate first adjusted asynchronous signal samples.

Abstract: According to one embodiment, there is provided a method, implemented in a magnetic disk drive, for adjusting a linear recording density. The method obtains a first flying-dependent error sensitivity for each of two or more heads. The first flying-dependent error sensitivity represents a change in read error rate corresponding to a change in flying height of the head during write. In addition, the method reduces the linear recording density of a first recording surface associated with a first head of the two or more heads if the first flying-dependent error sensitivity is a second flying-dependent error sensitivity higher than a threshold and corresponds to the first head.