Disclosed is a method for reducing spiral write time and clock reference
drift while writing spiral reference patterns on a disk of a disk drive.
The method includes: controlling a radial location of a 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, wherein a
substantial majority of the tracks each include a plurality of servo
sectors including a track number and a sync mark; measuring a distance
between first and second reference center positions of reference center
tracks of the first and second bands of tracks; and writing a spiral
reference pattern therebetween.