Abstract: A method for writing servo data includes: writing the servo data as the head moves outwardly towards a radial position on the disk one step at a time, wherein the same address data are written as the head moves outwardly in two consecutive steps, writing the servo data as the head moves inwardly towards the radial position one step at a time, so as to overwrite part of servo data that have been written in a previous step, wherein the same address data are written as the head moves inwardly in two consecutive steps, and writing either one of two-phase burst data, or address data and the other of said two-phase burst data, at the radial position.

Abstract: A method for writing servo data includes: writing the servo data as the head moves outwardly towards a radial position on the disk one step at a time, wherein the same address data are written as the head moves outwardly in two consecutive steps, writing the servo data as the head moves inwardly towards the radial position one step at a time, so as to overwrite part of servo data that have been written in a previous step, wherein the same address data are written as the head moves inwardly in two consecutive steps, and writing either one of two-phase burst data, or address data and the other of said two-phase burst data, at the radial position.

Abstract: 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.

Abstract: 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.

Abstract: According to one embodiment, a contact-detecting method includes calculating a representative value for each of a plurality of first zones. The plurality of first zones is provided at different radial locations on the disk. The representative value is calculated based on values measured at a plurality of different radial locations included in each of the first zones. The method includes detecting a contact point at which a first member contacts with a second member based on a first difference. The first difference is a difference between a value measured at an objective measuring point and a representative value of a second zone among the plurality of first zones. The objective measuring point is included in a third zone among the plurality of first zones. The second zone is arranged radially inward of the third zone.

Abstract: According to one embodiment, a head flying height control method includes detecting a contact of a head with a disk while floating the head from the disk and moving the head in a radial direction of the disk, increasing a flying height of the head after detecting the contact of the head with the disk, and decreasing the flying height of the head after a state where the contact of the head with the disk is not detected continues.

Abstract: According to one embodiment, a head flying height control method includes detecting a contact of a head with a disk while floating the head from the disk and moving the head in a radial direction of the disk, increasing a flying height of the head after detecting the contact of the head with the disk, and decreasing the flying height of the head after a state where the contact of the head with the disk is not detected continues.

Abstract: According to one embodiment, a magnetic disk device includes a reference head select module selects any one of magnetic heads as a reference head; a follow-up controller executes a follow-up control of a trajectory of the reference head based on a signal read by the reference head; and an eccentric controller executes an eccentric control of a trajectory of a magnetic head other than the reference head in order that an eccentric error between the trajectory of the reference head and the trajectory of the corresponding magnetic head is close to zero.

Abstract: According to one embodiment, a magnetic disk device includes a reference head select module selects any one of magnetic heads as a reference head; a follow-up controller executes a follow-up control of a trajectory of the reference head based on a signal read by the reference head; and an eccentric controller executes an eccentric control of a trajectory of a magnetic head other than the reference head in order that an eccentric error between the trajectory of the reference head and the trajectory of the corresponding magnetic head is close to zero.