Patent ID: 8295004

Claim:
A disk drive comprising: an actuator configured to move a head over a disk in a radial direction thereof; a servo controller configured to control the head to follow a target orbit on the disk, in accordance with a control value for the actuator; a calculation module configured to receive the control value from the servo controller and to calculate, as a disk runout value, a virtual target orbit value to be supplied to the servo controller in order to suppress a disturbance at the target orbit, in measuring a disk runout of the disk, the virtual target orbit value being calculated when the control value is substantially equal to zero; and an adjustment module configured to multiply the virtual target orbit value by a preset gain, and to input the virtual target orbit value to the servo controller without changing a phase of the virtual target orbit, wherein the adjustment module comprises a gain changing module configured to change the gain to 1 upon lapse of a threshold time after the servo controller has been activated.