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.

The magnetic tape includes a non-magnetic support; and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, in which the magnetic layer has a servo pattern, and an absolute value N of a difference between a refractive index Nxy measured regarding an in-plane direction of the magnetic layer and a refractive index Nz measured regarding a thickness direction of the magnetic layer is 0.25 to 0.40, a magnetic tape cartridge and a magnetic tape apparatus including this magnetic tape.

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).

According to one embodiment, a magnetic disk device includes a disk, a head, and a controller that estimates a first frequency component resulting from a disturbance in a first range of a frequency corresponding to the disturbance in a signal with the disturbance, estimates a second frequency component corresponding to a second frequency of a positive integral multiple of 2 or larger of a first frequency of the first frequency component in a second range different from the first range, and suppresses a first harmonic component corresponding to the positive integral multiple of the first frequency in a position error of a target position of the head on the disk.

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 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 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.

A magnetic disk device includes a magnetic disk that includes a plurality of tracks, a magnetic head for reading data from the magnetic disk, and a controller. The controller begins controlling the magnetic head to move to a second track of the plurality of tracks from a first track of the plurality of tracks before decoding of a first track signal output from the magnetic head is completed, wherein the first track signal is output from the magnetic head while the magnetic head is positioned over the first track.

A magnetic disk device includes a magnetic disk that includes a plurality of tracks, a magnetic head for reading data from the magnetic disk, and a controller. The controller begins controlling the magnetic head to move to a second track of the plurality of tracks from a first track of the plurality of tracks before decoding of a first track signal output from the magnetic head is completed, wherein the first track signal is output from the magnetic head while the magnetic head is positioned over the first track.

A data storage device is disclosed comprising a first voice coil motor (VCM) comprising a first voice coil configured to actuate a first head over a first disk, a second VCM comprising a second voice coil configured to actuate a second head over a second disk, and a spindle motor configured to rotate the first and second disk, wherein during a power failure the first and second disks rotating causes the spindle motor to generate a back electromotive force (BEMF) voltage. During the power failure the first and second VCMs are unloaded, wherein during a first interval the first voice coil is connected to the BEMF voltage and the second voice coil is disconnected from the BEMF voltage, and during a second interval the second voice coil is connected to the BEMF voltage and the first voice coil is disconnected from the BEMF voltage.