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List:       amanda-users
Subject:    Re: Linux 4mm SCSI DAT Drive Settings
From:       Stefan Monnier <monnier+lists/amanda/users/news/ () tequila ! cs ! yale ! edu>
Date:       1998-11-30 14:48:44
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>>>>> "Kai" == Kai Makisara <makisara@metla.fi> writes:
> The file linux/drivers/scsi/README.st explains the buffer allocation
> strategy.

Reminds me of a vaguely related question: how can I free the buffers
between tape uses (backups only run at night, so it would be good to
recover the buffer space during the day especially since it cannot be swapped)?
Using kerneld to load/unload the module kind of works, except that I
have to reissue the various `mt' commands to setup the device to my liking
(not a big deal, indeed) and (more importantly) that I lose the positioning
information: `mt status' can't tell any more if I'm at EOD, EOF, BOT or
whatnot.  This is annoying because I use this information to decide
whether I should append or not (it's only used as a hint so it also
works without the information, but if I don't have this information I have to
rewind/fsf the tape uselessly and I thoroughly dislike the idea of
`mt rewind; mt eod; append').


	Stefan

PS: another thing is: is there some way to tell if the drive is
    temporarily busy?  I issue a few `mt' commands at boot time
    but they sometimes fail because the drive is still rewinding.
    I couldn't come up with a way to tell the difference between
    a "busy" failure (where you might want to way and try again
    until it succeeds) and a genuine failure (where you *don't* want
    to retry indefinitely).

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