According to one embodiment, a magnetic disk device includes a first actuator which actuates a magnetic head portion including a magnetic head, a second actuator which adjusts a position of the magnetic heal on a magnetic disk in a radial direction of the magnetic disk, and a control portion which determines a second measurement signal amplitude when a second transfer function is measured in accordance with a first gain estimated value of the second actuator and an amplitude of a first measurement signal amplitude to the second actuator applied when a first transfer function is measured, which calculates a second gain estimated value of the second actuator based on the first transfer function and the second transfer function, and which updates the first gain estimated value, using the calculated second gain estimated value.

A data storage device is disclosed comprising a voice coil motor (VCM) having a resonance frequency, a first disk surface comprising a first set of servo sectors written at a frequency less than twice the VCM resonance frequency, and a second disk surface comprising a second set of servo sectors circumferentially offset from the first set of servo sectors and written at a frequency less than twice the VCM resonance frequency. An access of the first disk surface is performed by reading at least one of the first set of servo sectors to generate a first position error signal (PES), reading at least one of the second set of servo sectors to generate a second PES, and controlling the VCM based on the first PES and the second PES to position a first head over the first disk surface while accessing the first disk surface.

According to one embodiment, a magnetic disk device includes a magnetic disk, a first magnetic head and a second magnetic head that are moved independently of each other, a first controller chip, a second controller chip, and a third memory. The first controller chip includes a first processor and a first memory, and controls the first magnetic head. The second controller chip includes a second processor and a second memory, and controls the second magnetic head. Management information is stored in the third memory. The first controller chip is connected to the third memory. The second controller chip is connected to the third memory via the first controller chip. The second controller chip saves the management information into the second memory.

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 magnetic disk, a first magnetic head and a second magnetic head that are moved independently of each other, a first controller chip, a second controller chip, and a third memory. The first controller chip includes a first processor and a first memory, and controls the first magnetic head. The second controller chip includes a second processor and a second memory, and controls the second magnetic head. Management information is stored in the third memory. The first controller chip is connected to the third memory. The second controller chip is connected to the third memory via the first controller chip. The second controller chip saves the management information into the second memory.

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.

According to one embodiment, a magnetic disk device includes a magnetic disk including a plurality of tracks, first and second actuators, and a control circuit. The magnetic disk includes the plurality of tracks. The control circuit writes, in a first track by using the first actuator, second data having a size corresponding to a first number among the first data. In addition, the control circuit writes, in a second track by using the second actuator, third data having a size corresponding to a second number among the first data. Each of the first track and the second track is a track among the plurality of tracks. The first number is a number of writable sectors included in the first track. The second number is a number of writable sectors included in the second track. The third data is data received subsequent to the second data.

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 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.

According to one embodiment, a magnetic disk device includes a magnetic disk including a plurality of tracks, first and second actuators, and a control circuit. The magnetic disk includes the plurality of tracks. The control circuit writes, in a first track by using the first actuator, second data having a size corresponding to a first number among the first data. In addition, the control circuit writes, in a second track by using the second actuator, third data having a size corresponding to a second number among the first data. Each of the first track and the second track is a track among the plurality of tracks. The first number is a number of writable sectors included in the first track. The second number is a number of writable sectors included in the second track. The third data is data received subsequent to the second data.