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: 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: A magnetic tape media for storing data includes at least one servo band extending along the magnetic tape media and having servo information encoded by an M-ary alphabet A comprising M>2 different symbols and is arranged in a set of words. Each word of the set of words contains synchronization information, wherein each symbol used for representing the synchronization information is from a set B of m symbols, which set B is a proper subset of the symbols in the alphabet A such that 1?m<M; longitudinal position information, wherein each symbol used for representing the longitudinal position information is from a set C of M-m symbols, which set C is a complementary set to set B; and other information, wherein each symbol used for representing the other information is from the set C of M-m symbols.

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: 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: 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 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: 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: 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: 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: 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: 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: The relative trajectory of a transducer head over bit-patterned media (BPM) may be skewed with respect to a down-track direction on the media (i.e., skew error). In order to resolve the skew error, the presently disclosed technology measures the skew error without adding additional patterning on the media. A detector circuit detects a sequential series of data bits on a storage media. The sequential series of data bits alternate between at least two tracks on the storage media. The sequential series of data bits are sent to a timing circuit, which sets a time stamp indicating when each data bit is received using, for example, a delay chain or a voltage ramp. A time elapsed between receiving a first data bit, a second data bit, and a third data bit is tracked. Transducer head skew is adjusted based on a signal containing the time elapsed between the bits.

Abstract: A disk drive is disclosed comprising a head actuated over a disk, and a spindle motor operable to rotate the disk. A baseline relationship is generated between a baseline current draw of the spindle motor over a temperature range. An operating current draw of the spindle motor is measured and a corresponding operating temperature is measured. Failure of the spindle motor is predicted based on the operating current draw, the operating temperature, and the baseline relationship.

Abstract: A disk drive is disclosed comprising a head actuated over a disk, the head comprising a touchdown sensor comprising a resistance. A bias signal is applied at a reference value to the touchdown sensor at a reference temperature, and a corresponding reference resistance of the touchdown sensor is measured. An operating value for the bias signal is generated based on a predetermined operating temperature of the touchdown sensor, the reference resistance, the reference temperature, and a thermal coefficient of resistance (TCR) of the touchdown sensor, wherein the TCR specifies a change in temperature of the touchdown sensor relative to a change in the resistance of the touchdown sensor.

Abstract: A disk drive is disclosed comprising a disk comprising a plurality of tracks, a head attached to a distal end of an actuator arm, and a voice coil motor (VCM) operable to rotate the actuator arm about a pivot bearing including a race and a plurality of ball bearings. The VCM is controlled to execute a first jerk seek in a first radial direction so that the ball bearings slip within the race by a first rotation angle. The VCM is controlled to execute a second jerk seek in the first radial direction so that the ball bearings slip within the race by a second rotation angle, wherein the second rotation angle adds to the first rotation angle in order to rotate the ball bearings relative to the race at a reference angle of the pivot bearing.

Abstract: Aspects of the present invention relate to an apparatus and corresponding method that includes transitioning from a monitor state to a stop write state when a determined position error is greater than a threshold error value for a first predetermined period, and transitioning from the monitor state to a write state when the determined position error is less than the threshold error value for a second predetermined period. Write operations are enabled and signals are provided to operate an actuator to translate a magnetic head laterally in a manner to reduce the determined position error while in the write state. Write operations are disabled and signals are provided to operate the actuator to translate the magnetic head laterally in a manner to reduce the determined position error while in the monitor state. Write operations are disabled while in the stop write state.

Abstract: Grease wear leveling in a disk drive including an actuator for moving a head over a disk as part of a seek operation. A count of seek operations is maintained and when the count of seek operations exceeds a first threshold number, one or more full stroke seek (FSS) operations are performed until a count of the FSS operations performed reaches a predetermined number. The FSS operation includes moving the head through a substantially wide range of motion. For each of the one or more FSS operations performed, the count of FSS operations performed is adjusted based on whether the most recent FSS operation was performed within a time window. The time window is based at least on a number of interval seek operations performed since a previously performed FSS operation.

Abstract: A magnetic-recording head with a first thermal fly-height control (TFC) element and an embedded contact sensor element (ECSE) configurable as a second TFC element. The magnetic-recording head includes a write element, a read element, a first heater element, and an ECSE. The write element is configured for writing data to a magnetic-recording disk. The read element is configured for reading data from the magnetic-recording disk. The first heater element is configured as a first TFC element to coarsely adjust a fly-height of the magnetic-recording head with respect to the magnetic recording disk. The ECSE is configured to detect a contact with the magnetic-recording disk, and to function as a second heater element that is configured as a second TFC element to finely adjust the fly-height. The first heater element is configured with a first stroke-length larger than a second stroke-length of the second heater element for adjusting the fly-height.

Abstract: An apparatus and method for providing adaptive disturbance compensation with multi-rate synchronized sampling is disclosed herein. The dynamic disturbance occurring in a media drive during read/write operations is attenuated using the adaptive disturbance compensation scheme. A plurality of compensation filters are used, each of the compensation filters configured to attenuate a disturbance caused by a particular source within the media drive. Each of the compensation filters is computed based on a sampling rate relevant to the respective disturbances.