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.

An information processing apparatus includes an n-th parameter adjuster and an (n+1)-th parameter adjuster. The n-th parameter adjuster adjusts an n-th parameter set so that an n-th evaluation value set based on the n-th parameter set approaches an n-th target value set. The (n+1)-th parameter adjuster adjusts an (n+1)-th parameter set so that an (n+1)-th evaluation value set based on the (n+1)-th parameter set approaches an (n+1)-th target value set. In addition, the n-th parameter adjuster acquires, based on initial value set or search value set of the n-th parameter set, an n-th actual measured value set or an n-th predicted value set, acquires an (n+1)-th target value set based on the initial value set or the search value set of the n-th parameter set, and searches for the n-th parameter set that optimizes the (n+1)-th target value set under a restriction that the n-th evaluation value set approaches the n-th target value set using the acquired n-th actual measured value set or the n-th predicted value set and the acquired (n+1)-th target value set.

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.

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 data segments of a first data track, and second data is written to data segments of a second data track. After writing the second data, the first data is read at multiple off-track offsets of the first data track to measure an average off-track read capability (OTRC) of the first data track. A cross-track profile is generated for a first data segment of the first data track, and at least part of the cross-track profile is correlated with the measured average OTRC.

According to one embodiment, a magnetic disk device including a disk, a head, and a controller configured to, when writing a first servo sector, a second servo sector, and a third servo sector in the order described according to a second route varying in a radial direction of the disk with respect to a first route, adjust first timing used to write the second servo sector next to the first servo sector, and adjust second timing used to write the third servo sector next to the second servo sector.

The technology disclosed herein provides a method for generating an on-cylinder limit (OCLIM), the method including performing servo certification of a plurality of drives in a storage device to generate servo adaptive parameters (SAPs) by heads, generating a plurality of read adjust parameters (RAPs) by heads for the plurality of drives, generating an interim OCLIM value based on the SAPs by heads and RAPs by zones, and operating a disc drive write element using the interim OCLIM value.

A control circuit for a voltage regulator includes a divider coupled to the regulated output voltage to generate a divided voltage having a value that is a fraction of the regulated output voltage, an ADC responsive to the divided voltage to generate a feedback control signal, a digital compensator responsive to the feedback control signal and to a feedforward control signal scaled by a feedforward gain value to generate a compensator signal, and a pulse width modulator responsive to the compensator signal to generate a voltage control signal to control a switch of the voltage regulator. The digital compensator includes a register configured to store a value indicative of the input voltage and a feedforward gain unit configured to generate the feedforward gain value in response to the value indicative of the input voltage. In embodiments, the feedforward gain value is generated in response to the square of the value indicative of the input voltage. The feedforward gain value can be updated each time the value indicative of the input voltage is updated.

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.

A method of forming a patterned media includes constraining growth of magnetic grains in a down-track direction without constraining the growth in a radial direction to cause the magnetic grains to align in rows extending in the radial direction. The patterned media may allow for data track radial width to be defined independent of grain size.

A data storage device is disclosed comprising a coarse actuator configured to actuate a first head over a first disk surface and a second head over a second disk surface. A first fine actuator is configured to actuate the first head over the first disk surface, and a second fine actuator is configured to actuate the second head over the second disk surface. A first bias signal is calibrated for the first fine actuator, and a second bias signal is calibrated for the second fine actuator. The first fine actuator is controlled based on the first bias signal and the second fine actuator is controlled based on the second bias signal in order to concurrently access the first disk surface and the second disk surface.