A method of writing spiral tracks for a disk drive is disclosed. A first
concentric reference track is written at a first radial location near an
outer diameter of a disk surface, a second concentric reference track is
written at a second radial location near an inner diameter of the disk
surface, and a third concentric reference track is written at a third
radial location between the first and second radial locations. Prior to
writing one of the spiral tracks, the concentric reference tracks are
read to generate position error signals used to adjust a velocity profile
for writing the spiral tracks. The velocity profile is adjusted to
compensate for linear and non-linear disturbances due, for example, to
thermal expansion.