Abstract: Embodiments of the present invention utilize a hard disk drive buffer to minimize seek delays during background replication of a first volume and fulfillment of application input/output requests. According to one aspect of the present invention, a requested first sector of data is read along with one or more additional sectors of data. Upon determining that one or more of the read sectors of data should be replicated, the sectors are read from the disk buffer and written to a second volume.

Abstract: Systems, methods, devices, circuits for data processing, and more particularly to data processing including adjacent track interference mitigation.

Abstract: A disk drive is disclosed comprising a disk comprising a plurality of servo tracks defined by servo sectors, wherein each servo sector comprises servo data and a servo compensation value. While servoing a head over a target data track during a write operation, a position error signal (PES) is generated at each servo sector based at least in part on the servo data. When the servo compensation value of a first servo sector is recoverable, the write operation is aborted when the PES generated at the first servo sector exceeds a first write unsafe threshold. When the servo compensation value of the first servo sector is unrecoverable, the write operation is aborted when the PES generated at the first servo sector exceeds a second write unsafe threshold less than the first write unsafe threshold.

Abstract: Multiple signals are read, respectively, from multiple different cross-track positions of a track of a magnetic medium. Weighting coefficients for each of the multiple signals are determined. The weighting coefficients are applied to the respective signals to form weighted signals. The weighted signals are combined and the combined signal is used to recover data stored in the track.

Abstract: A data storage device and method for enabling dynamic fly height control which is insensitive to off-track motions is described. In some embodiments, a hard disk drive acquires signal data from neighboring overlapping tracks which are unwritten, thermally erased, or AC demagnetized. Side-to-side (off-track) positional errors or oscillations of the read head do not affect the signal which arises solely from the magnetic domains on the disk. Thus, signal variations may only arise from changes in the fly height. In other embodiments, neighboring overlapping data tracks are prewritten with reference data. The width of the neighboring overlapping tracks exceeds any expected side-to-side positional errors of the read head, thus signal variations may only arise from changes in the fly height. For all embodiments, the noise or reference data signal may serve as a reliable dynamic measure of the fly height with no effects arising from off-track motions.

Abstract: 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.

Abstract: A method and computer program product identify the location of a bad block on a disk platter of a hard disk drive, determine an avoidance area extending from the bad block, and prevent data from being written to the avoidance area.

Abstract: A disk drive is disclosed comprising a disk comprising a plurality of data tracks, and a head actuated over the disk, the head comprising an asperity sensor operable to generate a sensor signal having a magnitude based on a bias setting of the asperity sensor. The asperity sensor is configured with a first bias setting and a first asperity on the disk is detected based on the sensor signal generated at the first bias setting. The asperity sensor is configured with a second bias setting different from the first bias setting and a second asperity on the disk is detected based on the sensor signal generated at the second bias setting.

Abstract: A maximum velocity is dynamically determined during a tape drive operation to obtain a statistical standard deviation of a position error signal (PES) that yields an amount of stopwrite (SW) operations that avoids backhitching. The tape velocity is adjusted to the maximum velocity.

Abstract: According to one embodiment, a magnetic disk apparatus includes a magnetic disk having a plurality of tracks, each of the plurality of tracks having a plurality of servo areas and a plurality of data areas, the plurality of servo areas and the plurality of data areas being alternately arranged respectively, a magnetic head, and a processor. When a plurality of positioning errors related to one servo area are present in the first track, the processor updates the positioning error of the one servo area with a positioning error closest to a second track that is next to the first track. The processor writes data in the second track by a shingled write recording system by using the updated positioning error.

Abstract: A disk drive comprises a track follow control system having a plurality of selectable frequency modes, the track follow control system configured to receive a position error signal and to output a control signal based on the position error signal, wherein the control signal is used by a head assembly to position a head over a disk. The disk drive also comprises a state estimator configured to receive the control signal and a position signal indicating a position of the head, to estimate a disturbance based on the control signal and the position signal, and to output an estimated disturbance signal based on the estimated disturbance. The disk drive further comprises a disturbance evaluator configured to receive the estimated disturbance signal, and to select one of the frequency modes of the track follow control system based on the estimated disturbance signal.

Abstract: Disk drives with sliders including with an impedance compensation network in the signal path for the read sensor are described. The read signal bandwidth at the preamplifier is improved by the impedance compensation network to allow signals in the multi-GHz range from spin torque oscillators as well as tunnel magnetoresistance (TMR) sensors to be used. An embodiment of the invention achieves a signal layout balance by constructing two inductor-capacitor pair structures on the trailing edge of the slider that are integrated into the differential read signal traces. The differential balanced structure helps to suppress external signal interference pick-up from transferring from common-mode pick-up to differential mode.

Abstract: Technologies are described herein for implementing modulation coding schemes for TDMR. A data sequence is received to be stored on a first data track of a recording media. The first data sequence is encoded into a first codeword sequence using a modulation coding scheme, and the first codeword sequence is written to the first data track of the recording media. Subsequently, a second data sequence is received to be stored on a second data track of the recording media, the second data track being adjacent to the first data track. A second codeword sequence is generated for the second data sequence based on the first codeword sequence on the first data track, and the second codeword sequence is written to the second data track of the recording media.

Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of tracks, wherein each track comprises a plurality of servo sectors. The head is positioned over a first track, and when a first servo sector is processed, a first touchdown metric is evaluated to detect whether the head contacted the disk without evaluating a second touchdown metric. When a second servo sector is processed, the second touchdown metric is evaluated to detect whether the head contacted the disk without evaluating the first touchdown metric.

Abstract: An information recording device includes a recording medium that includes a data area, and a controller that controls recording of data on the recording medium, wherein in response to a request for execution of formatting of the data area of the recording medium, the controller does not record data for the formatting in the data area and records format information about the formatting in a nonvolatile recording area that is different from the data area.

Abstract: In one embodiment, a magnetic head slider includes at least one magnetic head element chosen from a group consisting of: a write element adapted for writing data to a magnetic recording medium and a read element adapted for reading data from the magnetic recording medium, a heater element adapted for controlling a flying height of the at least one magnetic head element above the magnetic recording medium, a contact sensor element adapted for detecting contact between the magnetic head slider near the at least one magnetic head element and the magnetic recording medium, and shared terminals adapted for supplying voltage to the heater element and for conveying signals from the contact sensor element. Other magnetic head sliders and methods of use are described according to additional embodiments.

Abstract: Embodiments of the present disclosure provide a method of self-servo writing, the method comprising actions of positionally tracking a selected timing track of a data storage disk, wherein the selected timing track has one or more timing segments; synchronizing an angular position signal to rotation of the data storage disk based on at least one of the one or more timing segments of the selected timing track; specifying servo sector positions relative to the synchronized angular position signal; writing servo sectors to the data storage disk at the specified servo sector positions relative to the synchronized angular position signal; detecting one or more positional errors in timing segments of a next timing track of the data storage disk based at least in part on the synchronized angular position signal; and accounting for the detected one or more positional errors in writing subsequent servo tracks. Other embodiments are also described.

Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of tracks including a first fly height calibration track and a second fly height calibration track. The disk drive further comprises a fly height actuator operable to control a fly height of the head in response to a fly height control signal. When a refresh event is detected, calibration data is written to the second fly height calibration track. After writing calibration data to the second fly height calibration track, the first fly height calibration track is read in order to calibrate the fly height control signal applied to the fly height actuator. After calibrating the fly height control signal, the second fly height calibration track is read in order to recalibrate the fly height control signal applied to the fly height actuator.

Abstract: A disk drive is disclosed comprising a head actuated over a disk, wherein a maximum radial movement of the head is limited. A plurality of access commands are stored in a command queue, and an access latency is determined for each command in the command queue, wherein the access latency is based at least on a seek latency for the head and a rotational latency for the disk. The access latency for each access command is increased by an offset based at least on a seek length for each access command, wherein the offset compensates for the limited maximum radial movement of the head. An access command is selected from the command queue based on the increased access latencies, and the selected access command is executed.

Abstract: Various embodiments of the present invention allow for the generation of at least one estimated value of a first parameter that is derived from a regularly measured value of a second parameter. In addition, a single control feedback signal can be adjusted via updating of the estimated and regularly measured values in a control feedback loop. At least one spiral track can be written to storage media based on the single control feedback signal, where the single control feedback signal can be received from an compensating circuit that receives the at least one estimated value of the first parameter, which can refer to position, and the at least one regularly measured value, which can refer to velocity.

Abstract: A system and method of writing servo write tracks to a rotating disk using a head having a read/write offset is disclosed. One embodiment utilizes a write element on the head to write the servo write tracks. A read element on the head is then positioned over the servo write tracks. The phase of a specific frequency component of the track shape error in the servo write track is measured during the positioning of the read element over the servo write track. A sine wave having a specific frequency and a phase is selected based on the measurement results. The sine wave is then applied to a servo system as a correction signal. A new servo write track is then written with the write element.

Abstract: Hardware-based methods and apparatus are provided for inter-track interference mitigation in magnetic recording systems. Inter-track interference (ITI) is mitigated in a magnetic recording system by obtaining ITI cancellation data; and providing the ITI cancellation data to an ITI mitigation circuit using a write data path in the magnetic recording system. The write data path can optionally operate substantially simultaneously with the read data path performing the read operation. The ITI cancellation data comprises, for example, user data and/or media data.

Abstract: A tape drive device for storing data in a tape cartridge includes a comparison unit that compares a transfer speed of the data transmitted from a host machine to the tape drive device with a speed threshold, a speed determination unit that determines a writing speed to a tape cartridge using the speed threshold, and a data write unit that writes data to the tape cartridge, the data write unit writing data to the magnetic tape provided for the tape cartridge when the determined writing speed is higher than the speed threshold, and the data write unit writing subsequent data following data written to the magnetic tape to the non-volatile semiconductor memory provided for the tape cartridge when the determined writing speed is lower than the speed threshold.

Abstract: The present disclosure relates to a perpendicular pole head for creating a perpendicular magnetic moment in a concentrated pattern for writing the pattern on perpendicular magnetic media, such as BaFe based media. The pole head can have flux concentrators in the shape of the written pattern, which can be repeatedly applied to a moving magnetic medium to create a timing pattern on the media, e.g., a servo timing pattern.

Abstract: A first data group in an access sequence is selected based on which data group in the data groups has a beginning closest to a current position of the tape medium. Those data groups located in specified regions of the tape medium are separated from other data groups located in alternative specified regions of the tape medium. The distance from the current position of the tape medium is set to be a logical distance value, determined by a calculation function, that is substituted for the physical distance value for the data groups that are located in the specified regions as compared with other data groups located in the alternative specified regions. A second data group in the access sequence is selected based on which remaining data group in the data groups has a beginning closest to an end of the first data group in the access sequence.

Abstract: A method for writing information to a magnetizable disk surface on a disk drive includes designating a plurality of regions on a disk where information is to be stored, writing information representing data to a first track in at least one of the plurality of regions, writing information representing data to a second track in the at least one of the plurality of regions, the information written to the second track overwriting a portion of the first track, and determining an amount of the first track that is overwritten based on a performance factor. Determining an amount of the first track that is overwritten is done or accomplished on the fly. The amount to overwrite the track is done in the field rather than in a factory or manufacturing facility.

Abstract: Misalignment of a transducer head over a bit-patterned media (BPM) may cause a bit to experience conflicting magnetization forces from the writer, resulting in improperly written data and stored data corruption. The likelihood of data corruption is reduced when a write transition is performed when the write sync margin is increased or maximized. Therefore, a write precompensation system may calculate time shift information for adjusting the timing of an individual write current transition at the transducer that compensates for write sync margin degradation due to any or all of skew angle of the transducer, track misregistration, and write field curvature.

Abstract: A servo system includes a first equalizer circuit operable to filter digital servo data samples derived from a first read head to yield first equalized data, a second equalizer circuit operable to filter digital servo data samples derived from a second read head to yield second equalized data, a first interpolator operable to interpolate the first equalized data to yield a number of first interpolated outputs at different phases, a second interpolator operable to interpolate the second equalized data to yield a number of second interpolated outputs at different phases, and a phase tracking and signal combining circuit operable to select and combine most closely aligned signals from the first interpolated outputs and the second interpolated outputs to yield a combined servo data signal.

Abstract: A control system for a tape drive that uses position error signals (PESs) generated by a tape head assembly of the tape drive during longitudinal movement of a tape through the drive to dynamically adjust a lateral and/or angular position of tape to enhance tape drive performance (e.g., the ability of a tape head assembly to precisely follow one or more data and/or servo tracks on the tape). In one arrangement, the PESs and/or PES metrics are used as feedback into the system to steer the tape by moving one or more tape path guides until subsequently generated PESs or PES metrics have been optimized or have at least moved back into an acceptable range or to acceptable levels. The disclosed control system facilitates achieving increased stringencies on PES minimization that come with increased tape drive magnetic track densities.

Abstract: According to one embodiment, a magnetic medium includes at least one recording layer including a first magnetic layer, a second magnetic layer and a non-magnetic layer. The first magnetic layer is form of a first magnetic material having a first magnetic anisotropy. The second magnetic layer is made of a second magnetic material having a second magnetic anisotropy different from the first magnetic anisotropy. The non-magnetic layer is made of a non-magnetic material and between the first and second magnetic layers, the first magnetic layer and the second magnetic layer being coupled such that directions of magnetization of the first and second magnetic layers are opposed to each other.

Abstract: A data processing system includes a cross-correlation calculator operable to calculate cross-correlations between an input signal and each of three different sync patterns associated with a target track and neighboring tracks, a detector operable to select a largest of the cross-correlations, a threshold comparator operable to compare the cross-correlations with a threshold to determine a direction of any position error of a read head, and a position error estimator operable to estimate a position error of the read head based at least in part on the cross-correlations.

Abstract: An apparatus for estimating head separation in an array reader magnetic recording system includes an array reader with multiple read heads operable to read data from a magnetic storage medium, a first preamplifier connected to a first read head, a second preamplifier connected to a second read head, and a head separation estimation circuit connected to the first preamplifier and to the second preamplifier, operable to estimate an integer phase offset and a fractional phase offset between a first signal from the first read head and a second signal from the second read head.

Abstract: Various approaches that reduce the width variability of storage media data tracks are described. First and second data tracks are written so that the second track overlaps the first track. After writing the second track data to the second track, an effective width of the first track is determined. The effective width of the first track is the portion of the first track that is not overlapped by the second track. One or more additional write operations to the recording medium are performed to compensate for the effective width of the first track being less than a threshold. The additional write operations may include one or more of rewriting the first track data to a third track on the storage medium and writing additional redundancy information to supplement the coding of the first track data.

Abstract: The present inventions are related to systems and methods for determining contact between two elements, and more particularly to systems and methods for determining contact between a head assembly and a storage medium.

Abstract: A method of writing servo data to a data storage medium includes reading a servo instruction from a memory, the servo instruction comprising a control portion and a data portion, processing the servo instruction in a controller to generate a servo data pattern from the data portion based on the control portion, and transferring the servo data pattern to the data storage medium. The processing may include transforming the data portion into the servo data pattern based on the control portion. The processing also may include following a command in the control portion to use the data portion as an index to retrieve a pre-programmed servo data pattern from a pattern store. The transferring may include storing the servo data pattern in a buffer, and writing the servo data pattern from the buffer to the data storage medium.

Abstract: In information recording areas of a disc-shaped magnetic recording medium, recording columns adjacent to each other relative to a radial direction are formed to partially overlap with each other in the radial direction. A first recording and a second recording are selectively performed. In the first recording, a first recording column, a second recording column (the outer adjacent recording column of the first recording column) and a third recording column (the outer adjacent recording column of the second recording column) are formed so that the radial positions of the inner and outer circumferential edges of the first recording column, those of a second recording column, and those of a third recording column satisfy R1in<R2in<R3in<R1out<R2out<R3out. In the second recording, a non-overlapping portion which does not overlap with any of the recording columns in the radial direction is formed on each of the recording columns.

Abstract: A servo system includes multiple interpolators operable to interpolate equalized data for multiple signal paths in a two dimensional magnetic recording system to yield interpolated signals at different phases, scaling circuits operable to scale the interpolated signals by adaptive scaling factors, a signal combining circuit operable to combine the scaled signals, a phase tracking circuit operable to select one of the phases of the combined signal, and an error gradient circuit operable to adapt the adaptive scaling factors.

Abstract: A modulated signal of a predetermined frequency is applied to a capacitive sensor of a magnetic head. The capacitive sensor is located proximate to a media-facing surface of the magnetic head. A clearance between the magnetic head and a magnetic medium is determined using a response to the modulated signal at the predetermined frequency.

Abstract: An apparatus comprises an alternating current coupling stage comprising a first filter configured to filter an analog signal to remove relatively low-frequency energy and read channel circuitry coupled to the alternating current coupling stage. The read channel circuitry comprises an analog-to-digital converter configured to convert the filtered analog signal to a digital signal, a detector configured to obtain a recovered signal using the digital signal, and a baseline correction module comprising a second filter and being configured to estimate a parameter of the first filter using a least mean squares algorithm based at least in part on the analog signal and an output of the second filter, adjust a parameter of the second filter based on the estimated parameter and add at least a portion of the removed relatively low-frequency energy to the digital signal by combining the output of the second filter and the digital signal.

Abstract: Systems and methods for making fast measurements of channel performance metrics such as error margin and off-track recording capability in shingled magnetic recording are provided. One such method involves writing a plurality of shingled tracks on the disk, measuring an off track read capability (OTRC) of each of the plurality of shingled tracks, determining radial endpoints of the measured OTRC for each of the plurality of shingled tracks, determining an approximate radial center for each of the plurality of shingled tracks based on the respective OTRC radial endpoints, and measuring a channel performance metric at a range centered around the approximate radial center for each of the plurality of shingled tracks. In one such case, the channel performance metric involves error margin. One such system includes a processor coupled to a memory, a magnetic transducer, and a test platform, where the processor is configured to perform the method.

Abstract: Hardware-based methods and apparatus are provided for inter-track interference mitigation in magnetic recording systems. Inter-track interference (ITI) cancellation data is stored in a memory of a read channel of a magnetic recording system. The memory can be in a write data path or a read data path of the read channel. The inter-track interference cancellation data is optionally provided to an inter-track interference mitigation circuit using at least a portion of a write data path, for example, based on a control signal. The storage of the inter-track interference cancellation data can be in response to a second control signal.

Abstract: A disk drive is disclosed comprising a disk comprising tracks defined by servo sectors, a head, and control circuitry comprising a servo control system operable to actuate the head over the disk based on the servo sectors. An estimated acceleration EstAccel of the head over the disk is generated based on at least one of the servo sectors. When the EstAccel is determined to be reliable, an estimated velocity EstVel of the head over the disk is generated based on the EstAccel. When the EstAccel is determined to be unreliable, the EstAccel is adjusted to generate an adjusted acceleration AdjAccel and the EstVel of the head over the disk is generated based on the AdjAccel.

Abstract: Approaches for a hard-disk drive (HDD) having a balanced resistive temperature detector (RTD). A HDD includes a head slider comprising a single RTD. A read/write IC comprises a balance resistor having the same resistance as the single RTD when the head slider is not in physical contact with the disk. The same amount of current flows through the single RTD and the balance resistor except when the head slider is in physical contact with the disk. Detecting a voltage change across the single RTD enables physical contact between the head slider and the disk to be accurately detected using a circuit with low noise. Alternately, the head slider may include two RTDs connected in sequence, and the balance resistor may possess the same resistance as the two RTDs. The two RTDs may vary inversely with environmental changes to avoid the need to recalibrate the balance resistor after any environmental change.

Abstract: A write head for a magnetic storage device includes a writing tip comprising a magnetic material, a write pulse generator configured to generate a write pulse signal comprising a varying voltage bias between the magnetic storage device and the writing tip. The write pulse signal comprising one or more write pulses effective to tunnel electrons from the writing tip to the magnetic storage device. The data stream generator configured to provide a data stream signal to the writing tip where the data stream signal is operative to vary spin polarity in the electrons from a first polarity to a second polarity.

Abstract: Systems and methods (e.g., “utilities”) of measuring errors in the positioning of tape head assembly data write and read elements of a tape drive and utilizing obtained calibration data to accurately align the data write elements with a desired position while writing data tracks and data read elements while reading previously written and aligned data tracks. The disclosed utilities independently determine a degree to which a tape drive write head is to be offset from a nominal write position of the write head over a tape and independently determine a degree to which a tape drive read head is to be offset from a nominal center position of previously written data track of the tape, each to collectively account for the various types of non-idealities in the write or read head of the tape drive (e.g., positioning errors between the data write/read elements and servo readers, etc.).

Abstract: A hard disk drive includes a control unit, a cache unit, a head unit, a platter unit, a spindle motor unit, a power supply unit, a switch unit, and an interface. When the switch unit is turned on, the power supply unit converts voltages of external power supplies received from the interface through the switch unit into operation voltages of the control unit, the cache unit, the head unit, the platter unit, and the spindle motor unit, and supplies the operation voltages to the control unit, the cache unit, the head unit, the platter unit, and the spindle motor unit. When the switch unit is turned off by the control unit, the voltages of the external power supplies cannot be transmitted to the power supply unit through the switch unit.

Abstract: A disk drive is disclosed comprising a disk comprising a plurality of data tracks defined by servo sectors. Each servo sector comprises a periodic preamble recorded at a first frequency, servo data, a periodic reference pattern recorded at a second frequency different from the first frequency, and at least one servo burst. A servo sector is processed by processing the periodic preamble to extract the servo data, demodulating the servo burst in response to the periodic reference pattern, generating a position error signal based on the extracted servo data and the demodulated servo burst, and measuring a fly height of the head based on the periodic reference pattern.

Abstract: A perpendicular magnetic recording disk has servo regions that have a patterned underlayer with seed layer pillars formed on the underlayer pillars above the underlayer trenches. The underlayer is made of an oxidizable material. Magnetic recording material is located on the seed layer pillars and on an oxide layer in the underlayer trenches. The magnetic material in the trenches exhibits a magnetic field substantially less than the magnetic field exhibited by the magnetic material on the seed layer pillars, which has perpendicular magnetic anisotropy. The reduced magnetic field from the trenches results from structural differences between the magnetic material on the seed layer pillars and in the trenches, such as smaller grain size of the magnetic material on the seed layer pillars and a wider distribution of crystallographic axes of the magnetic material in the trenches. The seed layer may be made of a material substantially non-reactive with oxygen.

Abstract: A magnetic-recording head with touch-down detector incorporating a carbon nano-tube (CNT). The magnetic-recording head includes a write element, a read element and a touch-down detector. The write element is configured to write data to a magnetic-recording disk. The read element is configured to read data from the magnetic-recording disk. The touch-down detector includes a thermal sensor, and a CNT portion. The thermal sensor is configured to convert heat to a voltage signal. The CNT portion is configured to touch down on the magnetic-recording disk. The CNT portion is also coupled to the thermal sensor, and is configured to transfer heat generated by contact between the CNT portion and the magnetic-recording disk to the thermal sensor. A hard-disk drive (HDD) including the magnetic-recording head with touch-down detector incorporating a CNT, and a method for detecting contact between the magnetic-recording head and a recording surface of a magnetic-recording disk are also provided.

Abstract: Systems and methods for improving accuracy of head positioning using existing servo patterns are provided. In one embodiment, a method for improving read head positioning is provided that comprises: writing a series of tracks over a range of read offsets to be calibrated; measuring a set of raw track profiles from the series of tracks; sampling the set of raw track profiles at a series of signal amplitude levels; constructing a reference track profile from the set of sampled track profiles; calculating a set of read offset deltas from each sampled track profile; merging the sets of read offset deltas into a set of average read offset deltas; and converting the set of average read offset deltas into a read offset correction table. A similar method for improving disk write head positioning is also provided which utilizes such a read offset correction table to eventually create write offset correction table.