Patent ID: 7145744

Claim:
A method for reducing spiral write time and clock reference drift while writing spiral reference patterns on a disk of a disk drive, the disk drive comprising control circuitry and a head disk assembly (HDA) comprising the disk, an actuator arm, a head connected to a distal end of the actuator arm, and a voice coil motor for rotating the actuator arm about a pivot to position the head radially over the disk, the method comprising: controlling a radial location of the head for writing a first band of tracks near one of an outer diameter (OD) circumference of the disk or an inner diameter (ID) circumference of the disk and for writing a second band of tracks near the other of the OD circumference of the disk or the ID circumference of the disk, respectively, a substantial majority of the tracks each including a plurality of servo sectors including a track number and a sync mark; determining a first reference center position for a center track of the first band of tracks and a second reference center position for a center track of the second band of tracks; moving the head to a first predicted position for the first reference center position; moving the head to a second predicted position for the second reference center position; measuring the distance between the first and second reference center positions; and writing the spiral reference pattern from the first reference center position towards the center track of the second band of tracks based upon the measured distance between the first and second reference center positions.