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Date:      Fri, 27 Dec 1996 10:40:29 -0800
From:      Julian Elischer <julian@whistle.com>
To:        Greg Lehey <grog@lemis.de>
Cc:        FreeBSD SCSI Mailing List <freebsd-scsi@freebsd.org>
Subject:   Re: Explain this you SCSI tape experts!  :-)
Message-ID:  <32C4181D.167EB0E7@whistle.com>
References:  <199612270825.JAA02999@freebie.lemis.de>

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Greg Lehey wrote:
> 
> Julian Elischer writes:
> > J Wunsch wrote:
> >>
> >>  As Sean Kelly wrote:
> >>
> >>  As fate would have it, that's the very tape I need.  But when I stick it
> >>  in the drive, FreeBSD reports BLANK CHECK.  Doh!
> >>
> >>  What could cause that?
> >>
> >>  No idea why there's nothing on the tape, but BLANK CHECK does of
> >>  course mean you're trying to read beyond the recorded medium area.
> >
> > didi you rewind it accidentally between sets?
> > did you rewind if after the last one?
> 
> I wish I understood what happened here.  I would almost guess that you
> (Sean) have mistaken the tape for another one which is really blank.
> In any case, it's not a question of rewinding: helical scan drives
> rewind tapes before ejecting them, even if you have specified
> /dev/nrst*.  I can't see how you could write anything on the tape
> without first writing at the start, and after loading again, it will
> definitely be positioned at BOT.
> 
> Greg

I've seen people use /dev/rst0 instead of nrst0 and then every 'close'
rewinds the device.
If the s/w does a write data/close/open/write EOF/write EOF/close
sequence on rst0 it will result in the 2xEOF (== EOM) being at
the front of the tape. The tape will then return BLANK CHECK
if you try read past that.



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