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Date:      Wed, 19 Apr 1995 21:50:21 -0400
From:      steve2@genesis.tiac.net (Steve Gerakines)
To:        questions@FreeBSD.org
Subject:   Re: QIC-80 for backups - is this right?
Message-ID:  <199504200150.VAA17244@genesis.tiac.net>

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> Well, personally I've never been a big fan of these tapes drives (I've
> definately had problems with them).  However, the problem you describe
> sounds a heck of a lot like you hit a bad spot on the tape and the
> driver just keeps rewriting over and over.  Are you running V1.1.5.1
> or V2.0R?  Version 2 is much better at handling this type of thing...
> with V1 the driver had the annoying habit of just sitting there forever
> and ever trying to write the tape.

This problem still exists in the current version of the driver, although
it happens less frequently than earlier versions.  The way to recover
from such a thing is to have the driver realize that this is a bad block
and then automatically update the bad sector map.  Once the bad sector map
is updated you need to recalculate error correction and then re-write
the tape segment, skipping over the newly marked bad spot.

Because error correction is currently outside the driver it is
impossible to recover.  I'm re-doing the driver now and this is one
feature it'll have.

> The solution.  Believe it or not I find that reformatting the tape (yup,
> spending 2 hours doing it) with the DOS based formatting program (none
> available under FreeBSD :-( will generally fix the problem.  This will
> reestablish the bad block map and generally set things up pretty well.

That usually solves it, but not without a re-boot or yanked tape first. :-(

- Steve
steve2@genesis.tiac.net



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