A data storage device having a housing member for a selected one of a 3 inch form factor hard disc drive (HDD) or a 2 inch form factor HDD. A spindle motor coupled to the housing member supports a rotatable data recording disc with a plurality of data tracks and an outermost perimeter. The outermost perimeter has an average overall radius of 48.5 millimeters, mm responsive to the housing member being for a 3 inch form factor HDD or an average overall radius of 33.5 mm responsive to the housing member being for a 2 inch form factor HDD. The rotatable data recording disc further has an outermost data track at an average selected radius such that the difference between the average overall radius of the outermost perimeter and the average selected radius is more than 1 mm.

A data storage device comprises a lead actuator that actuates a first read-write head over a first disk and a support actuator that actuates a second read-write head over a second disk. A spindle motor rotates the first and second disks. In response to an emergency power off (EPO) event, a processing device retracts and parks the actuators using an internal supply voltage generated from a back electromotive force (BEMF) voltage of the spindle motor, and brakes the spindle motor. The spindle motor is not braked until both the lead and support actuators have been retracted and parked.

Various aspects are directed to a data storage device comprising one or more disks, an actuator mechanism configured to position a selected head among one or more heads proximate to a corresponding disk surface among the one or more disks, and one or more processing devices. The one or more processing devices are configured to detect repeatable runout (RRO) noise components from a measurement of fly height of the selected head above one or more sectors of a fly height measurement track, and remove the detected RRO noise components from one or more per-sector readback signal measurements.

A voice coil motor (VCM) includes a coil, and on a first side a first yoke having a coil-side facing the coil, a first low-coercivity permanent magnet positioned between the coil and the coil-side of the first yoke and having a yoke-side facing the first yoke and a coil-side opposing the yoke-side, and a first high-coercivity permanent magnet adjoining the coil-side of the first low-coercivity magnet. A second side of the VCM on the opposing side of the coil is similarly configured. The permeance coefficient of such a VCM enables magnetic stability of low-coercivity magnetic materials. Additional high-coercivity permanent magnets may be bonded to the coil-sides of each of the first and second yokes and adjoining the yoke-sides of each of the low-coercivity permanent magnets, if the relative thicknesses of the magnet materials so dictate by design.

Disclosed herein is a motor driver circuit including a logic circuit that generates a second code which changes linearly with a slope a with respect to a first code based on a position command for a linear motor to be driven and that can switch the slope a, a D/A converter that converts the second code into an analog control signal, and a driver that drives the linear motor such that a current detection signal indicating a drive current of the linear motor approaches a target value that changes linearly with a slope g with respect to the control signal, the driver being configured to switch the slope g. The motor driver circuit is switchable between a first state in which g=g.sub.1 and a=a.sub.1 and a second state in which g=g.sub.2 (where |g.sub.2|>|g.sub.1|) and a=a.sub.2=a.sub.1(g.sub.1/g.sub.2).

Disclosed herein is a motor driver circuit including a logic circuit that generates a second code which changes linearly with a slope a with respect to a first code based on a position command for a linear motor to be driven and that can switch the slope a, a D/A converter that converts the second code into an analog control signal, and a driver that drives the linear motor such that a current detection signal indicating a drive current of the linear motor approaches a target value that changes linearly with a slope g with respect to the control signal, the driver being configured to switch the slope g. The motor driver circuit is switchable between a first state in which g=g.sub.1 and a=a.sub.1 and a second state in which g=g.sub.2 (where |g.sub.2|>|g.sub.1|) and a=a.sub.2=a.sub.1(g.sub.1/g.sub.2).

A voice coil motor (VCM) includes a coil, and on a first side a first yoke having a coil-side facing the coil, a first low-coercivity permanent magnet positioned between the coil and the coil-side of the first yoke and having a yoke-side facing the first yoke and a coil-side opposing the yoke-side, and a first high-coercivity permanent magnet adjoining the coil-side of the first low-coercivity magnet. A second side of the VCM on the opposing side of the coil is similarly configured. The permeance coefficient of such a VCM enables magnetic stability of low-coercivity magnetic materials. Additional high-coercivity permanent magnets may be bonded to the coil-sides of each of the first and second yokes and adjoining the yoke-sides of each of the low-coercivity permanent magnets, if the relative thicknesses of the magnet materials so dictate by design.

According to one embodiment, a magnetic disk device includes a disk, a read head, and a control unit. The control unit includes a read processing unit that executes first read processing of moving the read head to n1 radial positions within a period in which the disk makes m1 rotations and reading the data of the track, a comparison unit that derives a first signal of highest quality, and a determination unit that determines a radial position at which the first signal of the highest quality is derived as a first appropriate read position. Where 1m1<n1.

Various illustrative aspects are directed to a data storage device comprising one or more disks, an actuator arm assembly comprising one or more disk heads and a voice coil motor (VCM), the VCM configured to operate in a PWM mode and a linear mode, and one or more processing devices configured to: seek the VCM towards a target track in the PWM mode; transition the VCM from the PWM mode to the linear mode, wherein the transitioning comprises switching an offset compensation value from a first offset compensation value to a second compensation offset value to compensate for a transition offset induced while transitioning the VCM from the PWM to the linear mode, wherein the first and the second offset compensation values correspond to the PWM and linear modes, respectively, and seek the VCM towards the target track in the linear mode for a linear mode time.

According to one embodiment, a magnetic disk device includes a disk, a write head, an adjustment unit, and a write processing unit. The adjustment unit adjusts each of a first adjustment value, a second adjustment value, and a third adjustment value. The write processing unit can select shingled magnetic recording and perform write processing based on the first to third adjustment values. When the number of the plurality of tracks of the band is t+1 and the number of unused sectors among the plurality of sectors of the band is e. The adjustment unit adjusts the first to third adjustment values to establish ext.