A method and apparatus for writing spiral servo information onto one or
more disk surfaces at a variable velocity using a servo track writer
(STW) is provided. In one embodiment, a variable velocity profile is
chosen so that spiral crossing angles across the disk surface are set to
be equal. In another embodiment, a variable velocity profile is chosen so
that spiral crossing angles across groups of tracks (i.e., two or more
tracks) are set to be equal. In yet another embodiment, a variable
velocity profile is chosen to adjust the number of tracks per inch (TPI)
across the disk surface.