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Date: Thu, 19 May 2005 18:04:41 -0400
From: Gary Corcoran <gcorcoran@rcn.com>
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cc: freebsd-hardware@freebsd.org
Subject: Re: Weird behaviour of AIT-3 and (g)tar
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Tulio Guimarăes da Silva wrote:
> Hello again,
> 
>    I´m having some trouble putting a Sony SDX-700V SCSI AIT-3 unit to 
> work on FreeBSD 5.3-RELEASE.
...
>  Besides the speed, hardware compression seems to not being funcional 
> either. I already tried every 4 possible dip switch setting for 
> compression, but I am still not able to transfer a 180GB archive to a 
> (should-be) 260GB medium.

I can't help you with most of your problems, but regarding the "compression"...

I would guess that if you have 180GB to backup, it's not all text.  :)
When I last used a tape drive years ago, when writing to a 2GB tape
that would supposedly hold 4GB compressed, I could fit only about 1.9GB
before the tape was full.  Turning off hardware compression, I could fit
2GB.  The problem was that I was saving already compressed multimedia files,
and the tape drive's "compression" just added overhead and took up more space.
So unless you're backing up text or similar files, don't believe the
marketing hype about getting 2x the amount onto your tapes...

Gary