From owner-freebsd-questions  Tue Dec 14 13: 2:31 1999
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To: Adon <ahwang@fas.harvard.edu>
Cc: freebsd-questions@FreeBSD.ORG
Subject: Re: DDS-4 set density woes 
In-Reply-To: Message from Adon <ahwang@fas.harvard.edu> 
   of "Tue, 14 Dec 1999 15:36:40 EST." <Pine.OSF.4.10.9912141531400.5936-100000@is04.fas.harvard.edu> 
Date: Tue, 14 Dec 1999 16:02:19 -0500
From: Mitch Collinsworth <mkc@Graphics.Cornell.EDU>
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>i have a HP SureStore DAT40i (HP C5683A C908).  it is a DDS-4 drive that
>purports to write to smaller formats such as DDS-2 or DDS-3.  my problem
>is when i try to write to a DDS-2 tape.  in its default configuration, i
>cannot write the full capacity of the tape (4 GB uncompressed).  with
>hardware compression turned on, i get about 3.6 GB on a tape.

Is the data you're writing already compressed before it goes to the
tape?  Hardware compressing a file that is already software compressed
will actually end up making it bigger rather than smaller.  From your
numbers above it sounds like this might be what's happening here.

-Mitch


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