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Message-ID: <3CCD107D.F7F4498F@iee.org>
Date: Mon, 29 Apr 2002 10:21:01 +0100
From: Don Sharp <dwsharp AT iee DOT org>
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To: gnuwin32 <cygwin AT cygwin DOT com>
Subject: Re: Cygrunsrv and backups
References: <229D7C0FE0BED311A0E800805F0DD471010D2DC3 AT wn01ex DOT wn DOT gb DOT solvay DOT com>
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"Craveiro, Marco" wrote:
> 
> "Don Sharp" wrote:
> 
> > > anyway, there's just one thing i dont understand on your script:
> > >
> > >         mt -f /dev/nst0 tell
> > >
> > > why do you need this?
> > >
> >
> > One doesn't strictly need it. I use it to tell me how near to a full
> > tape I am using so I reshuffle what goes on which tape when it proves
> > necessary.
> >
>         hey, that is quite cool as I want to add 2 tests to my script (is
> the tape full, is the tape empty). how do i interpret the tell output, i.e.
> whats the max blocks on a compressed dds-2 tape?

The initial

mt -f /dev/nst0 status

reports

tape capacity    :  1760887 KB          remaining        :  1760887 KB
current block    :        0             write protected  :      
no             datcompression   :       on

Note the tape capacity report. This is NOT a constant as bad blocks are
removed from the capacity automatically. The tape is a DDS-1 of
nominally 2Gb capacity.

The tape blocks reported by "tell" depends on the blocking set before.
In my case because I am using default tar blocking it reports in 10K
blocks. However I have noticed that if I run an NT backup beforehand,
"tell" reports in 1K blocks. I believe that you can set the block size
for the hardware using "mt".

HTH

Don Sharp

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