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.

According to one embodiment, a disk device includes a base, a discoidal recording medium including an innermost circumferential portion and an outer circumferential edge, a head, a head actuator provided pivotably on the base and supporting the head movably, a first sensor which detects a shock and a drive unit which pivots, when the shock detected by the first sensor is greater than a predetermined value and the head is located at a position less than a predetermined distance from the innermost circumferential portion, the head actuator to place the head at a position more than the predetermined distance which satisfies a conditional formula below.

[00001]$D=9.83e^{-210\frac{t^2}{G}}$

According to one embodiment, a magnetic disk device includes a disk including a recording region including a servo sector, a head configured to write data to the disk and read data from the disk, and a controller configured to acquire a plurality of correction data for a repeatable runout of the recording region, the correction data respectively corresponding to a plurality of measurement positions set based on a first linearity error acquired by reading the servo sector, and to correct a position of the head based on the correction data.

According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head, a sensor, a non-volatile semiconductor storage device, and a controller. The magnetic head performs writing and reading to and from the magnetic disk. The sensor detects a degree of a physical influence applied from an outside. The controller generates a log when a detection value detected by the sensor satisfies a condition for abnormality determination, and stores the log in the non-volatile semiconductor storage device in response to generation of the log.

According to one embodiment, a disk device includes a base, a discoidal recording medium including an innermost circumferential portion and an outer circumferential edge, a head, a head actuator provided pivotably on the base and supporting the head movably, a first sensor which detects a shock and a drive unit which pivots, when the shock detected by the first sensor is greater than a predetermined value and the head is located at a position less than a predetermined distance from the innermost circumferential portion, the head actuator to place the head at a position more than the predetermined distance which satisfies a conditional formula below. $D=9.83e^{-210\frac{t^2}{G}}$

According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head, a sensor, a non-volatile semiconductor storage device, and a controller. The magnetic head performs writing and reading to and from the magnetic disk. The sensor detects a degree of a physical influence applied from an outside. The controller generates a log when a detection value detected by the sensor satisfies a condition for abnormality determination, and stores the log in the non-volatile semiconductor storage device in response to generation of the log.

According to an embodiment, a magnetic disk device includes a magnetic disk, a magnetic head, and a controller. The magnetic disk records servo marks thereon. The controller determines, based on a time interval at which the servo marks are read by the magnetic head, whether the magnetic disk device has transitioned from a first state where a position of the magnetic disk device does not vary with time to a second state where a position of the magnetic disk device varies with time.

According to one embodiment, a storage device includes a storage medium, and a controller which controls reading and writing of data from and to the storage medium. The controller detects write-off-track having a write-off-track amount larger than a threshold value when the data is written, and interrupts writing of the data when the write-off-track is detected. The controller acquires a degradation amount of a write speed or a degree value indicating a degree of the write-off-track, when the write-off-track amount is equal to or smaller than the threshold value. The controller changes the threshold value based on the degradation amount or the degree value.

A data storage drive includes a servo loop for positioning a head over a disc. The servo loop includes a sensor, located in the head, that senses servo information located on the disc and produces a servo signal therefrom. The servo signal is combined with a reference signal to produce a raw position error signal (PES). The servo loop further also at least one phase-matching disturbance attenuation (PMDA) filter that receives the raw PES as an input and responsively outputs a vibration-cancellation signal, which, when combined with the raw PES, cancels vibration-induced disturbance from the raw PES, thereby producing a refined PES. A servo controller receives the refined PES and responsively produces a servo control signal. An actuator moves the head in response to receiving the servo control signal.

A hard disk drive includes a disk having a servo region and data tracks. The servo region has servo data for formatting some of the data tracks for high capacity storage and others of the data tracks for low capacity storage. A head writes user data to the high capacity tracks in response to vibration less than a threshold value, and otherwise writes the user data to the low capacity tracks.