A data storage system comprises: a head configured to produce a signal representing data stored on a storage medium; an estimator configured to determine an estimated signal comprising a superposition of an estimated linear portion of a partial-response equalizer output and an estimated nonlinear portion of the signal; a bank of noise whitening filters configured for filtering a difference between the signal and the estimated signal; a branch metric calculator configured to calculate branch metrics based on the filtered signal; and an adaptive data-dependent noise-predictive maximum likelihood sequence detector configured to generate an output stream representing the data based on the one or more branch metrics.

According to one embodiment, a magnetic disk device includes an actuator assembly including an actuator block including a rotatable bearing unit, a plurality of heads movably supported by the actuator assembly, a first sensor provided to the actuator block, and a second sensor provided at a position different from the first sensor.

According to one embodiment, a magnetic disk device includes an actuator assembly including an actuator block including a rotatable bearing unit, a plurality of heads movably supported by the actuator assembly, a first sensor provided to the actuator block, and a second sensor provided at a position different from the first sensor.

According to one embodiment, a magnetic disk device includes an actuator assembly including an actuator block including a rotatable bearing unit, a plurality of heads movably supported by the actuator assembly, a first sensor provided to the actuator block, and a second sensor provided at a position different from the first sensor.

According to one embodiment, a magnetic disk device includes an actuator assembly including an actuator block including a rotatable bearing unit, a plurality of heads movably supported by the actuator assembly, a first sensor provided to the actuator block, and a second sensor provided at a position different from the first sensor.

Apparatus and method for disturbance rejection in a control system. In some embodiments, a controller is adapted to position a control object. A disturbance observer generates a disturbance compensation value which is applied to reduce position error resulting from application of mechanical disturbance to the control object. The disturbance observer includes an adaptive filter with at least one dead zone providing a pass-through response with a scalar gain of less than one.

An actuator pivot shaft assembly for a multi-actuator data storage device may include one or more annular grooves extending radially inward from an outer surface of the pivot shaft, thereby desirably weakening or structurally decoupling the shaft between the actuators, to assist with inhibiting transmission of vibration between the actuators during operation. The shaft assembly may further include an elastomeric damper positioned within the annular groove(s), to damp transmission of vibrational forces between the actuators through the shared shaft.

Various illustrative aspects are directed to a data storage device comprising data tracks N and N?1, and one or more processing devices, configured to identify, during a track write on the data track N, a write abort event based upon an expected risk for the data track N?1 exceeding a risk threshold, read one or more sectors of the data track N?1 and collect one or more corresponding sector metrics, verify the one or more sectors based upon the collected sector metrics, wherein the verifying comprises assigning each of the one or more sectors as one of a readable or a non-readable sector, and continue the track write on the data track N upon determining each of the one or more sectors is a readable sector, or recovering and relocating the data track N?1 based on determining at least one of the sectors is a non-readable sector.

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 data storage device is disclosed comprising a voice coil motor (VCM) configured to actuate a head over a disk. The head is used to read data recorded on the disk to generate a read signal, and the read signal is processed to generate a current command signal at a servo sample rate having a servo sample interval. A current flowing through the VCM is detected, and a current error signal is generated based on a difference between the current command signal and the detected current flowing through the VCM. An analog command signal is generated based on the current error signal, and the analog command signal is applied to the VCM. A saturation in the analog command signal is detected, and a first deglitch window is generated during which the saturation detection is disabled, wherein the first deglitch window is programmed relative to the servo sample interval.