According to one embodiment, a magnetic disk device includes a first actuator system, a second actuator system, a first controller, and a second controller. A first magnetic head is provided at a tip of the first actuator system. A second magnetic head is provided at a tip of the second actuator system. The first controller controls the first actuator system and relatively moves the first magnetic head with respect to the magnetic disk. The second controller controls the second actuator system and relatively moves the second magnetic head with respect to the magnetic disk. While the first magnetic head is retracted, the second controller acquires first information corresponding to input to the first actuator system and uses the first information to perform positioning control of the second magnetic head.

According to one embodiment, a disk device includes a plurality of recording media, a plurality of magnetic heads, a plurality of blades, and a housing. The recording medium has a recording surface, is rotatable around a rotation axis extending in an axial direction intersecting the recording surface, and is aligned in the axial direction. The magnetic head is configured to read and write information from and to the plurality of recording media. The plurality of first blades forms a spoiler, and the first blades of the plurality are located in a plurality of gaps provided between the plurality of recording media. The housing is provided with an inner chamber in which the plurality of recording media, the plurality of magnetic heads, and the plurality of first blades are accommodated. The number of first blades is smaller than the number of gaps.

Systems and techniques for writing data to a Shingled Magnetic Recording (SMR) magnetic data storage device. At least one processor may determine whether the distance between a first data track and a second data track is less than a threshold distance. If the distance is less than a threshold distance, the at least one processor may cause a write head to refrain from writing to the sector of the second data track. The at least one processor may cause data from the first data track to be copied to another storage location and write data to the sector of the second data track.

The technology disclosed herein pertains to a method for determining expected command completion time (CCT), the method including receiving a plurality of position error signals (PESs) for an HDD over a predetermined time period, determining sigma of the plurality of PESs, retrieving upper off-track limits (UOL) for one or more data sectors of the HDD, calculating average number of retrieved sectors (A) between two consecutive occurrences of the |PES|>UOL for the HDD, and determining required number of revolutions (CCT) to collect data based on the average number of retrieved data sectors (A) and a total number of requested data sectors (N).

A magnetic disk apparatus of one of the embodiments stores read position dependency information on read signal quality of a data region at a first track and measures the read signal quality at a predetermined radial position in a second data region of a second track different from the first track. A positioning error of the second data region is determined based on the read position dependency information and the read signal quality at the predetermined radial position. Data is recorded in a recording target data region in a shingled recording so as to prevent data written in the second data region from being overwritten by data in a recording target data region adjacent to the second data region by using the determined positioning error.

A magnetic disk apparatus of one of the embodiments stores read position dependency information on read signal quality of a data region at a first track and measures the read signal quality at a predetermined radial position in a second data region of a second track different from the first track. A positioning error of the second data region is determined based on the read position dependency information and the read signal quality at the predetermined radial position. Data is recorded in a recording target data region in a shingled recording so as to prevent data written in the second data region from being overwritten by data in a recording target data region adjacent to the second data region by using the determined positioning error.

Systems and methods for compensating for hysteresis in a disc drive are described. In one embodiment, a method may use an inverse hysteresis model to linearize effects of hysteresis of a microactuator in the disc drive. The hysteresis model may be a Coleman-Hodgdon hysteresis model. The hysteresis of the microactuator may be characterized, and the inverse hysteresis model may be based at least in part on the characterization. The inverse hysteresis model may be used to implement a digital filter. The digital filter may be employed in series with the microactuator to linearize the effects of hysteresis.

A method for writing servo data includes writing servo data as a head moves outward on a disk one step at a time, so as to overwrite part of servo data that have been written in a previous step, writing servo data as the head moves inward on the disk one step at a time, so as to overwrite part of servo data that have been written in a previous step, and writing one of two-phase burst data, or address data and the other of said two-phase burst data, at the radial position, so as to overwrite at least part of servo data written in each last step of the writings as the head moves outward and inward. The same address data are written in two consecutive steps as the head moves outward and as the head moves inward.

A system may compensate for skew in a patterned medium, such as but not limited to a self-assembling bit patterned medium, with a write pole separated from a data storage medium by an air bearing. The write pole being connected to a controller. The data storage medium can have a plurality of magnetic islands arranged in data tracks with each data track having a track center. The write pole may be selectively shifted from the track center by the controller to compensate for a skewed write pole configuration.

According to one embodiment, a magnetic disk drive in the present embodiment includes a disk including tracks, each including servo sectors, a head, and a controller configured to acquire first correction data for repeatable runout occurring in a first direction, and second correction data different from the first correction data, to write the first correction data within a first permitted range in the first direction, to write the second correction data within a write permitted range including the first permitted range and a second permitted range in a second direction opposite to the first direction, to read at least one of the first correction data and the second correction data, and to correctly place the head.