Patent ID: 7633705

Claim:
A disk drive comprising: a disk configured to be rotated by a spindle motor and comprising a plurality of servo data items recorded and spaced at predetermined intervals in a circumferential direction; a magnetic head configured to read data from the disk and to write data from the disk; an actuator configured to move the magnetic head in a radial direction of the disk; a temperature sensor configured to detect a temperature ambient to the disk; a disk-runout measuring module configured to measure a disk runout of the disk; a storage module configured to store disk-runout information representing the disk runout as information which is used for offset adjustment when the actuator is controlled and the magnetic head is positioned; a servo-interval measuring module configured to measure servo intervals, each being a time interval between two adjacent servo data items; a disk-shift detecting module configured to detect a disk shift of the disk based on the temperature detected by the temperature sensor and servo-interval information representing a change of the servo interval; and an updating module configured to cause the disk-runout measuring module to measure a disk runout and to update the disk runout information stored in the storage module in accordance with the disk runout which the disk-runout measuring module measures when the disk-shift detecting module detects the disk shift of the disk.