According to one embodiment, a magnetic disk device includes a disk including a plurality of servo data items, a head including a write head which writes data to the disk, and a first read head and a second read head which read data from the disk, and a controller configured to position the head based on a first signal in which write data positioned between the servo data items of the disk is read by the first read head, and a second signal in which the write data is read by the second read head separated from the first read head in a radial direction of the disk.

A data storage device is disclosed comprising a head actuated over a disk comprising servo data for defining a plurality of data tracks, wherein each data track comprises a plurality of data segments. First data is written to a first data segment of a first data track, and second data is written to a second data segment of a second data track. After writing the second data, a quality metric is measured for at least two off-track offsets of the first data segment. A track pitch is estimated between the first data segment and the second data segment based on the quality metrics, and a track trajectory is generated for the second data segment based on the estimated track pitch. Third data is written to the second data segment based on the track trajectory.

A self servo-write process in performed on two or more recording surfaces simultaneously. In a dual-stage servo system, a first fine positioning servo system that includes a first microactuator independently controls the position of a first read/write head over a first recording surface of a hard disk drive, while a second fine positioning servo system that includes a second microactuator independently controls the position of a second read/write head over a second recording surface of the hard disk drive.

A data storage device is disclosed comprising a disk comprising servo data, a spindle motor configured to rotate the disk, and a head actuated over the disk. A position error signal (PES) is generated based on the servo data, and the head is actuated over the disk based on the PES. While swinging a speed of the spindle motor, the swinging is disabled based on the PES.

According to one embodiment, a magnetic disk device includes a disk, a head for writing data to the disk and reading data from the disk, and a controller configured to detect a positioning error of the head as the head is writing the data in a first track of the disk, and change a first threshold value for interrupting the writing based on one or more evaluation values corresponding to a possibility of correcting error data in the first track of the disk. The controller interrupts the writing when detecting the positioning error of the head writing the first track that exceeds the first threshold value.

Provided herein is an apparatus including a disk drive base, wherein the disk drive base includes a first metal composition with a first CTE (coefficient of thermal expansion). A disk drive cover is attached to the disk drive base, wherein the disk drive cover includes a second metal composition with a second CTE that are different from the first metal composition and the first CTE. An arm is connected to a reader and a writer, wherein the arm is coupled to the disk drive base, the reader and the writer are separated by a distance, and the distance affects an MR (magnetoresistive) offset. In response to temperature changes between 0 C. and 60 C., the first material and the second material expand and contract comparably and proportionally. In further response to the temperature changes between 0 C. and 60 C., a change in the MR offset is less than 10% or a preferably defined range of a track pitch on a recording medium attached to the disk drive base.

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 disk, a head including a write head and a first and a second read head, and a controller configured to generate a correction value based on placement information on the write head and the first and the second read head, a first distance between the first read head and the second read head in a case where the first read head is placed at a first position of the disk, and a second distance between the first read head and the second read head in a case where the first read head is placed at the first position, and to correct positions of the heads based on the correction value in a case where first data written with the first read head placed at the first position is read.

A controller of a magnetic disk device obtains, for each of a plurality of first position sets, a first distribution that is a radial distribution of differences between a target orbit of the magnetic head and an actual position of the magnetic head while correcting a disturbance synchronized with rotation of the magnetic disk by using correction amounts at a plurality of positions included in one of the plurality of first position sets. The controller performs weighting the first distribution according to a position in the radial direction and calculating an evaluation value based on the weighted first distribution for each of the plurality of first position sets. The controller selects a second position set from the plurality of first position sets based on the evaluation value. The controller records correction amounts at a plurality of positions included in the second position set by the magnetic head.

A method for writing repeatable run-out (RRO) data, to surfaces of a rotating magnetic storage medium in a storage device having two read channels, includes detecting, with a first head, using a first read channel, a servo sync mark (SSM) on a first track on a first surface, establishing a recurring servo-gating signal at a successive fixed interval from the SSM, detecting, with the first head, servo signals from the first track on occurrence of the recurring servo-gating signal, processing the servo signals from the first track, to generate first positioning signals for positioning the first head relative to the first track, following a similar procedure with a second read channel having a second head to generate second positioning signals for the second read head, and writing first and second RRO data to servo wedges of the first and second tracks according to the respective positioning signals.