Nice discourse and very informative.
Do you have a couple of specific examples of publically available "low
level format" utilities? I for one would be happy to leave the servo track
intact if I have a forensically strong way to wipe data.
On Wed, 30 Mar 2005 14:38:43 EST, PC Sage Information Services said:
surely there's a low level format utility lying about here and there if
you know the right geometry, I'm sure you can make it work...
Actually, no. Almost all "low-level format" utilities make the assumption
that the servo track is intact enough to find where the tracks are
supposed
to be - the heads that read the servo info usually don't even *have* a
write circuit. The basic problem is that the positioning gear that moves
the heads isn't perfect - it moves to where the drive *thinks* the track
is
and then "hunts" left and right a bit until it finds the strongest signal.
It's in general *NOT* adequate enough to fly *blind* and write a servo
track.
If your tracks are every 0.01" with a tolerance of 0.0025" (just making up
numbers), and your seek is accurate to 0.0020", you can be pretty sure
that
you'll land on the track, and be able to zero in that last 0.0020" on the
servo signal.
If you *write* the servo signal and you're off by 0.0020" one way, and
then the
next time you go to find the track, you're off by 0.0020" the *other* way,
then
the servo track is 0.0015" out of range - and you can't find the track
anymore.
Even worse, if the next track over is *also* out-of-spec, you can end up
accidentally
aquiring the servo signal for the *wrong* track. Whoops. ;)
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