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.

According to one embodiment, servo patterns different in servo pattern frequency are recorded in zones divided in a radial direction on a magnetic disc, and the servo patterns in the adjacent zones overlap each other in a predetermined area from a zone servo boundary between the zones, and a determination boundary where it is determined to execute a crossing process is set within the overlapping area of the servo patterns upstream from the zone servo boundary, based on position information on a seek destination and the present position of the magnetic head.

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.

Disclosed are hard disk drives (HDDs), and methods for use therewith, that utilize reduced overhead servo fields, thereby simplifying the servo system. Reduced overhead servo fields may be of particular use in HDDs that utilize multi-revolution storage techniques to store data at much higher densities than what is possible for conventional HDDs. The relaxed performance requirements of high-density, multi-revolution drives provides opportunities for reducing servo overhead, thereby potentially further increasing the areal density capability of the magnetic media. Servo overhead may also be reduced by placing certain servo data on flash or other memory off of the media disk rather than in the servo fields written to the media disk.

Disclosed are hard disk drives (HDDs), and methods for use therewith, that utilize reduced overhead servo fields, thereby simplifying the servo system. Reduced overhead servo fields may be of particular use in HDDs that utilize multi-revolution storage techniques to store data at much higher densities than what is possible for conventional HDDs. The relaxed performance requirements of high-density, multi-revolution drives provides opportunities for reducing servo overhead, thereby potentially further increasing the areal density capability of the magnetic media. Servo overhead may also be reduced by placing certain servo data on flash or other memory off of the media disk rather than in the servo fields written to the media disk.