According to one embodiment, when an inspection of a defect of a recording surface of the magnetic disk is carried out by using the first processing section and the second processing section on the basis of the output of the gap sensor, a magnetic disk device is configured to compare a threshold defined on the basis of outputs of the first processing section at a plurality of tracks excluding a track which is an inspection object and an output of the first processing section at the track which is the inspection object with each other and, when the output of the first processing section at the track which is the inspection object exceeds the threshold, detect that there is a defect on the track concerned of the magnetic disk.

According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head, an actuator, a first stopper, an acceleration sensor, and a controller. The magnetic head is configured to record and reproduce data on and from the magnetic disk. The actuator is configured to rotate about a rotation axis to move the magnetic head. The first stopper is configured to block the actuator in rotation to restrict the actuator from rotating about the rotation axis in a first direction. The acceleration sensor is configured to output an electric signal corresponding to applied acceleration. The controller is configured to, at a time when the actuator abuts against the first stopper, apply a first drive signal to the actuator to measure a first electric signal output from the acceleration sensor, the first drive signal being for driving the actuator in the first direction.

According to an embodiment, a magnetic disk is provided with a track, and the track is provided with a data sector. The data sector includes a plurality of servo regions in which servo data is written, and a plurality of first data regions. Each of the plurality of first data regions is disposed between two servo regions of the plurality of servo regions. The controller executes a first write operation of writing data sequentially to the plurality of first data regions using the magnetic head. After the first write operation, the controller executes a second write operation of retrying the writing to a second data region in which the write error is detected among the plurality of first data regions, and not retrying the writing to a third data region in which the write error is not detected among the plurality of first data regions.

In an approach to adaptive tape calibration criteria based on the number of stop writes, the number of rewrite occurrences caused by a stop write is determined for each specific tape drive type. Responsive to detecting a stop write during a write operation, the total number of stop writes is stored on the tape drive. A rewrite calibration threshold is determined, where the rewrite calibration threshold includes the total number of stop writes on the tape drive and a calibration reference value for the specific tape drive type. Responsive to the number of rewrite occurrences caused by the stop write exceeding the rewrite calibration threshold while writing a data set on the tape drive, a calibration of the tape drive is performed.

Systems and methods are disclosed for an actuator device or actuator control device to implement a low power savings mode. For example, a device can comprise an actuator arm including a first actuator and a second actuator, the second actuator configured to refine a movement of the actuator arm to a more precise position than use of merely the first actuator. A device can also comprise a control system configured to determine when the device is in an idle state and, when the device is in the idle state, disable the second actuator and perform a positional seek operation with the second actuator disabled. Power savings can occur from disabling the second actuator, which may also include disabling associated circuitry, such that it does not consume power or consumes a nominal (e.g., negligible or insignificant) amount of power during the associated seek operation.

Systems and methods are disclosed for an actuator device or actuator control device to implement a low power savings mode. For example, a device can comprise an actuator arm including a first actuator and a second actuator, the second actuator configured to refine a movement of the actuator arm to a more precise position than use of merely the first actuator. A device can also comprise a control system configured to determine when the device is in an idle state and, when the device is in the idle state, disable the second actuator and perform a positional seek operation with the second actuator disabled. Power savings can occur from disabling the second actuator, which may also include disabling associated circuitry, such that it does not consume power or consumes a nominal (e.g., negligible or insignificant) amount of power during the associated seek operation.

According to one embodiment, a magnetic disk device includes a disk, a head that writes data to the disk and reads data from the disk, and a controller that corrects a first signal into a first likelihood value by machine learning based on a correct learning signal set with a likelihood other than 1 and an incorrect learning signal set with a likelihood other than 0 and executes error correction processing based on a second likelihood value according to the first signal and the first likelihood value.

According to one embodiment, when an inspection of a defect of a recording surface of the magnetic disk is carried out by using the first processing section and the second processing section on the basis of the output of the gap sensor, a magnetic disk device is configured to compare a threshold defined on the basis of outputs of the first processing section at a plurality of tracks excluding a track which is an inspection object and an output of the first processing section at the track which is the inspection object with each other and, when the output of the first processing section at the track which is the inspection object exceeds the threshold, detect that there is a defect on the track concerned of the magnetic disk.

A method for writing repeatable run-out data, representing a recurring contribution to position error, to a rotating constant-density magnetic storage medium, includes repeating, for each respective track at a respective radius of the constant-density magnetic storage medium, (1) determining a respective track pattern frequency based on track location and desired data density, (2) locating a position in a respective servo wedge on the respective track based on servo sync mark detection, (3) writing the repeatable run-out data to the respective servo wedge at a time delay, from the location of the position in the respective servo wedge, that is inversely proportional to the respective radius, to achieve a predetermined offset, and (4) repeating the determining, the locating and the writing for each servo wedge on the respective track of the constant-density magnetic storage medium.

A data storage device is disclosed comprising at least one head configured to access a magnetic tape comprising a plurality of servo frames each comprising a plurality of servo bursts, wherein each servo burst comprises a plurality of servo stripes. The servo stripes in a first servo burst are read using the head to generate a first read signal that is processed using a first matched filter matched to the first servo burst in order to generate an average time stamp for the servo stripes in the first servo burst. A position error signal (PES) is generated based on the average time stamp of the first servo burst, and the head is positioned relative to the magnetic tape based on the PES.