Patent ID: 6906884

Claim:
A magnetic disk apparatus comprising: a head having a recording/reproducing device for writing and reading out a servo signal onto and from a magnetic disk; an actuator having a head arm for supporting and moving said head to a position above said magnetic disk in a servo track movement operation and a driving means for driving said head arm; a range limiting stopper for limiting a movable range of said actuator; a range specifying stopper for setting a specific range of said actuator in said movable range of said actuator; and a control unit for writing a servo signal into said specific range at servo track movement pitch based on servo tracks recorded with said servo signal, correcting said servo track movement pitch on the basis of the number of servo tracks in said specific range and executing control to write said servo signal at corrected servo track movement pitch; wherein, if a result of comparison of the number of servo tracks recorded with said servo signal in said specific range with a predetermined value indicates that the number of servo tracks is greater than said predetermined value, said servo track movement pitch is increased and a servo signal is recorded onto areas outside said specific range at said increased servo track movement pitch.