Abstract: A magnetic disk device includes a disk, a head configured to write data on the disk, and a controller. The controller generates a target trajectory of the head in a circumferential direction for writing to a plurality of sectors in a current track, wherein the target trajectory is based on an actual trajectory of the head for writing to a plurality of sectors in a previously written track that is adjacent to the current track, determines that the previously written track is discontinuous between an initial sector of the previously written track and an end sector of the previously written track by a radial offset, generates a corrected trajectory for writing the plurality of sectors in the current track, and controls a position of the head in a radial direction based on the corrected trajectory while writing to the plurality of sectors in the current track.

Abstract: According to one embodiment, a magnetic disk apparatus includes a magnetic head, a voice coil motor, a driving circuit, and a VCM resistance estimation unit. The magnetic head accesses a magnetic disk. The voice coil motor drives the magnetic head over the magnetic disk. The driving circuit applies a VCM current to the voice coil motor. The VCM resistance estimation unit estimates a VCM resistance in the voice coil motor based on the saturated VCM current and a velocity of the magnetic head.

Abstract: A magnetic disk device includes a magnetic disk having a plurality of tracks, a magnetic head used for writing data on the magnetic disk and reading data from the magnetic disk, a controller configured to control seek operations of the magnetic head, and a vibration sensor. The controller predicts a first vibration caused by a currently executed seek operation, based on a seek control signal, predicts a second vibration based on vibration detected by the sensor, and determines an adjusted start time of the currently executed seek operation so that a phase of the first vibration does not match a phase of the second vibration.

Abstract: According to one embodiment, a VCM resistance estimation unit estimates a VCM resistance in a voice coil motor based on an acceleration and a velocity of a magnetic head with a VCM voltage saturated, and an equivalent current force constant estimation unit estimates an equivalent current force constant of the voice coil motor based on the acceleration and the velocity of the magnetic head with the VCM voltage saturated.

Abstract: According to one embodiment, there is provided a disk apparatus including a first disk, a second disk, a main actuator, a first actuator, a second actuator, a third actuator, and a driver circuit. The driver circuit is configured to be able to switch between a first mode and a second mode. The first mode is a mode where a first actuator, a second actuator, and a third actuator are driven in a same direction. The second mode is a mode where the first actuator and the second actuator are driven in opposite directions and where the third actuator and the second actuator are driven in opposite directions.

Abstract: 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.

Abstract: According to one embodiment, a magnetic disk device includes a memory, a disk including track groups each including overlapping tracks, a head including a write head, and a read head, and a controller configured to write first position data, including a first position error of the write head with respect to a first target track, to the memory and a second recording area subsequent to a first recording area to which first data is written, when writing the first data to the track groups, to read the first position data from the memory or the second recording area when adding data after writing the first data, and to control a position of the write head based on the first position data.

Abstract: According to one embodiment, there is provided a disk apparatus including a first disk, a second disk, a main actuator, a first actuator, a second actuator, a third actuator, and a driver circuit. The driver circuit is configured to be able to switch between a first mode and a second mode. The first mode is a mode where a first actuator, a second actuator, and a third actuator are driven in a same direction. The second mode is a mode where the first actuator and the second actuator are driven in opposite directions and where the third actuator and the second actuator are driven in opposite directions.

Abstract: 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.

Abstract: According to one embodiment, a magnetic disk drive includes a disk including a plurality of servo areas for detecting a positioning error, a head to write and to read data, and a processor. The processor detects a current positioning error of the head on the disk, while writing data to tracks of the disk so as to partially overlap with each other, calculates a predicted positioning error in a next servo area, determinates write inhibit, based on comparison between the current positioning error and a first threshold value, sets the first threshold value to a smaller value being used as the first threshold value to determinate the write inhibit in the next servo area.

Abstract: According to one embodiment, a data storage apparatus includes a disk configured to be recorded correction information corresponding to radial positions of the disk and variation information corresponding to the correction information, each of the correction information being information for correcting a repeatable runout, and each of the variation information being information corresponding to a variation amount of a repeatable runout, and a controller configured to correct a first repeatable runout at a first radial position by using a first correction information and a first variation information which are recorded at a second radial position of the disk, when the head is controlled to be positioned at the first radial position on the disk.

Abstract: 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 singled 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.

Abstract: In a disk drive apparatus, there is provided with a controller which determines a demodulated positioning error from a demodulated position and a target position, wherein the demodulated position is obtained by demodulating a servo signal readout from the disk. The controller estimates a demodulation noise amount which is included in the demodulated position on the basis of a signal quality of the servo signal, and corrects a predetermined off-track threshold with a correction value which is obtained from the estimated demodulation noise amount. A write operation of writing data on the disk is inhibited, if the demodulated positioning error exceeds the corrected off-track threshold.

Abstract: According to one embodiment, there is provided a method for generating address data. The method generates a first code corresponding to a cylinder number. The cylinder number is divided and recorded on servo sectors in association with an identification of a cylinder on a disk. The first code is formed of some codes obtained by dividing the cylinder number based on a number of each of the servo sectors. The method generates a second code corresponding to address data for each of the servo sectors, by encoding the first code based on the servo sector number and a servo format number. The servo format number is used to identify a format of each of the servo sectors.

Abstract: According to one embodiment, a data storage apparatus includes a disk, a head and a controller. In each track, first and second correction values for correcting a track runout in synchronization with rotation of the disk are recorded. The first correction value is for a first position located within a first track, and the second correction value is for a second position located within a second track adjacent to the first track, and separated from the first track by a predetermined distance. The head writes data to or read data from the tracks. The controller corrects the track runout with the first and second correction values, when the head is controlled to position at a target track.

Abstract: According to one embodiment, there is provided a method for generating address data. The method generates a first code corresponding to a cylinder number. The cylinder number is divided and recorded on servo sectors in association with an identification of a cylinder on a disk. The first code is formed of some codes obtained by dividing the cylinder number based on a number of each of the servo sectors. The method generates a second code corresponding to address data for each of the servo sectors, by encoding the first code based on the servo sector number and a servo format number. The servo format number is used to identify a format of each of the servo sectors.

Abstract: According to one embodiment, a disk storage apparatus includes a servo system. The servo system includes a state observer and performs a seek operation up to a target position with a current position of a head undetermined. The servo system performs the seek operation based on initial values including a temporary position, while allowing the state observer to operate based on the initial values, until the current position is determined. The servo system determines the current position based on the servo data read from the plurality of servo areas by the read module and a result of estimation by the state observer.

Abstract: According to one embodiment, a magnetic disk apparatus includes a magnetic disk having a plurality of tracks, each of the plurality of tracks having a plurality of servo areas and a plurality of data areas, the plurality of servo areas and the plurality of data areas being alternately arranged respectively, a magnetic head, and a processor. When a plurality of positioning errors related to one servo area are present in the first track, the processor updates the positioning error of the one servo area with a positioning error closest to a second track that is next to the first track. The processor writes data in the second track by a shingled write recording system by using the updated positioning error.

Abstract: According to one embodiment, a disk storage apparatus includes an interrupt controller and a servo controller. The interrupt controller determines whether or not to carry out servo interrupt processing and holds a number of negative results of the determination. The servo controller includes an internal model configured to calculate an estimated current position of the head. The servo controller corrects a state of the internal model based on the number of negative results of the determination and performs head positioning control based on a result of a calculation of the internal model, if the result of the determination by the interrupt controller is affirmative.

Abstract: According to one embodiment, an information write apparatus writes a track on a magnetic disk by a shingled write recording method. The information write apparatus calculates a write target position of the track based on a pitch. The information write apparatus calculates a positioning error. The information write apparatus stores the calculated positioning error. The information write apparatus integrates positioning errors of tracks written before the predetermined track is written, and corrects a write target position based on the integrated positioning error. The information write apparatus controls the position of the write head based on the corrected write target position.