According to one embodiment, a magnetic disk device includes a magnetic disk including at least one servo zone that includes a first data storage track with a first servo pattern having a first frequency and a second data storage track with a second servo pattern having a second frequency, wherein the first data storage track is located closer to an outer diameter of the magnetic disk than the first data storage track and the first frequency is greater than the second frequency; a magnetic head that faces the magnetic disk; and a zone servo switching unit that switches a servo pattern frequency employed to position the magnetic head in a radial direction based on a radial position of the magnetic head.

According to one embodiment, a magnetic disk device includes a disk, a head including a main magnetic pole having a first end and a second end opposite to the first end in a radial direction of the disk, a write shield facing the main magnetic pole with a gap, and an assist element provided in the gap and at a position where a first distance between the first end and the assist element and a second distance between the second end and the assist element are different from each other, and a controller which controls a voltage applied to the assist element according to a shingled write direction in which a second track is overwritten on a first track.

A system includes a read/write module and a caching module. The read/write module is configured to access a first portion of a recording surface of a rotating storage device. Data is stored on the first portion of the recording surface of the rotating storage device at a first density. The caching module is configured to cache data on a second portion of the recording surface of the rotating storage device at a second density. The second portion of the recording surface of the rotating storage device is separate from the first portion of the recording surface of the rotating storage device. The second density is less than the first density.

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.

According to one embodiment, a magnetic disk device includes a base that includes a bottom wall and side walls standing along a circumference of the bottom wall, a housing that includes a cover facing the bottom wall and closing the base, an actuator assembly that is housed inside the housing and is rotatable around a rotation axis, a head movably supported by the actuator assembly, a control circuit board provided outside of the housing, a first sensor disposed on the control circuit board, and a second sensor disposed inside the housing.

A data storage device is disclosed comprising a first disk comprising a first disk surface, a second disk comprising a second disk surface, an elevator actuator configured to actuate a head along an axial dimension relative to the first and second disks, a radial actuator configured to actuate the head radially over the first disk surface or the second disk surface, and a position sensor configured to generate a sinusoidal sensor signal representing a position of the head along the axial dimension. A crashstop_offset along the axial dimension is measured from a crashstop position of the elevator actuator to a zero crossing of the sinusoidal sensor signal.

A method for writing data in a disk drive having actuators each controlling arms extending over disk surfaces, including: receiving a write command from a host; receiving from the host data; dividing the data into data blocks; determining: a first surface from the disk surfaces where data is written by a first head of an arm controlled by a first actuator of the actuators; and a second surface from the disk surfaces where data is written by a second head of an arm controlled by a second actuator of the actuators; determining storage blocks of each of the first and the second surface; and writing first data blocks of the divided data blocks to the determined storage blocks of the first surface using the first head while writing second data blocks of the divided data blocks to the determined storage blocks of the second surface using the second head.

According to one embodiment, a magnetic disk device includes a base that includes a bottom wall and side walls standing along a circumference of the bottom wall, a housing that includes a cover facing the bottom wall and closing the base, an actuator assembly that is housed inside the housing and is rotatable around a rotation axis, a head movably supported by the actuator assembly, a control circuit board provided outside of the housing, a first sensor disposed on the control circuit board, and a second sensor disposed inside the housing.

A method for writing data in a disk drive having actuators each controlling arms extending over disk surfaces, including: receiving a write command from a host; receiving from the host data; dividing the data into data blocks; determining: a first surface from the disk surfaces where data is written by a first head of an arm controlled by a first actuator of the actuators; and a second surface from the disk surfaces where data is written by a second head of an arm controlled by a second actuator of the actuators; determining storage blocks of each of the first and the second surface; and writing first data blocks of the divided data blocks to the determined storage blocks of the first surface using the first head while writing second data blocks of the divided data blocks to the determined storage blocks of the second surface using the second head.

Systems and methods are disclosed for timing servo operations within a channel based on a counter for a disc locked clock. In certain embodiments, an apparatus may comprise a servo channel configured to lock a frequency of a servo channel clock to a rotational velocity of a disc data storage medium, and maintain a counter of clock cycles for the servo channel clock. The servo channel may perform operations to read servo data from a servo sector on the disc data storage medium at a first counter value selected relative to a target counter value corresponding to an expected location of a servo timing mark (STM).