A data storage device is disclosed comprising a head actuated over a disk comprising servo data for defining a plurality of data tracks, including consecutive data tracks N1, N, and N+1. Data is written to data track N using a position error signal (PES) generated by reading the servo data, and a read track trajectory for data track N is generated based on the PES of the write. Data is read from data track N based on the read track trajectory for data track N.

According to one embodiment, a magnetic disk device includes a disk, a first head, a second head, an actuator configured to position the first head and the second head over the disk, and a controller configured to control the actuator based on a first value having a first waveform suppressing a disturbance component, wherein the controller is configured to invert, in the first waveform, a polarity of a third waveform succeeding a first timing with respect to a polarity of a second waveform preceding the first timing in a case where the first head is changed to the second head at the first timing.

A data storage device is disclosed comprising a first actuator configured to actuate a head over a disk, a second actuator configured to rotate the disk, a first control circuit configured to generate a servo command, and a second control circuit configured to receive the servo command from the first control circuit, control the first actuator or the second actuator using the servo command, and override the servo command to avoid an overcurrent condition.

A first time period is determined during which a first head driven by a first actuator will be performing a track-following operation. A second time period is also determined during which a second head driven by a second actuator will be performing a low-priority disk access operation that includes a seek. The first and second actuators are independently movable such that the first and second disk access operations are capable of being performed in parallel. If it is determined that the seek of the second head will impact servo control of the track-following operation of the first head, a start time of the seek of the second head is changed to correspond to a time that mitigates impacts to the track-following operation of the first head.

According to one embodiment, a magnetic disk device comprises a JIT seek control unit, which uses second time series data of a current indication value of a VCM that sets a slope having an absolute value smaller than an absolute value of a slope of a first time series data in at least one of a monotonically decreasing interval of an acceleration interval and a monotonically decreasing interval of a deceleration interval of a head or an operation acceleration of the head.

According to one embodiment, a disk device includes a rotatable magnetic disk, an actuator which supports and moves a head, a ramp which holds the head at an unloaded position, a motor which rotates the magnetic disk, and a controller which performs a load operation and a seek operation. When a radial travel speed of the head during the load operation is referred to as Vr1, a circumferential travel speed of the head is referred to as Vt1, a radial travel speed of the head during the seek operation is referred to as Vrs, and a circumferential travel speed is referred to as Vts, the controller controls at least one of the radial travel speed of the head and number of revolutions of the magnetic disk to satisfy a relationship (Vr1/Vt1)<(Vrs/Vts).

A method involves determining a threshold error rate that will result on data stored on a magnetic disk surface of a disk drive being unrecoverable. The method also involves determining a seek velocity that will overwrite sufficient portions of the data such the data will exhibit at least the threshold error rate. The disk drive performs at least one traversal of the magnetic disk surface with a head of the disk drive that emits an erase field during the at least one traversal at the seek velocity. The at least one traversal sanitizes the data.

Various illustrative aspects are directed to a data storage device, comprising one or more disks; an actuator mechanism configured to position heads proximate to a recording medium of the disks; a spindle motor configured for rotating the one or more disks; and one or more processing devices comprising a servo control processor. The servo control processor is configured to receive a spindle speed error signal indicative of an error in a rotational speed of the spindle motor. The servo control processor is further configured to output an initial frequency offset signal, wherein the initial frequency offset signal is proportional to the spindle speed error signal.

A method includes calculating, by a data storage device processor, at least one access trajectory from a first disc surface location to at least one second disc surface location at which at least one primary data access operation is to be carried out. The method also includes determining, by the data storage device controller, whether an opportunity to commence at least one secondary data access operation exists along or proximate to the at least one access trajectory from the first disc surface location to the at least one second disc surface location.

A method of operating a storage device includes reading data from a storage medium using a detector, processing signals from the detector through a plurality of processing circuits, each respective processing circuit in the plurality of processing circuits being optimized for a different state of a channel condition and providing a respective output metric, selecting a processing circuit from the plurality of processing circuits by comparing the respective output metrics from each processing circuit in a predetermined manner, and designating as output of the detector output of the processing circuit that is selected. The output metrics may be branch metrics or path metrics, and the channel condition may be fly-height or phase shift. The storage device includes a storage medium, and a read channel including a detector, and processing circuits that process signals from the detector. Each respective processing circuit is optimized for a different state of a channel condition.