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Date:      Mon, 7 Mar 2005 09:47:31 -0500 (EST)
From:      Jerry McAllister <jerrymc@clunix.cl.msu.edu>
To:        freebsd-questions@freebsd.org
Cc:        Jerry McAllister <jerrymc@msu.edu>
Subject:   Re: What's the easiest way to do a backup and verify?
Message-ID:  <200503071447.j27ElWW10343@clunix.cl.msu.edu>
In-Reply-To: <1946173739.20050307145644@wanadoo.fr> from "Anthony Atkielski" at Mar 07, 2005 02:56:44 PM

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> 
> Is there an easy way to combine a backup and verify when doing backups
> with dump?
> 
> On Windows NT it's just a matter of checking a box.  I seem to recall
> the last time I looked into this on UNIX there was no easy way to
> accomplish a verify operation for a backup, but perhaps things have
> changed with FreeBSD 5.3 (?).
> 
> I've never had a problem with backup (I backup to DAT tape), but I'd
> feel better if every backup was followed by a verify to make sure the
> tape is readable.

Actually, if used frequently for backups - such as every day, DAT is
notoriously prone to failure.    So, it is a good idea to check dumps
made to DAT.   Unfortunately, there is not a reasonable way to 
automatically do it.   There is a verify, but it cannot work on a
running system, because it compares files (inodes) on the tape back
to the ones on disk.  Any changes mean an error, even if it was a
real change in the file between the time it was written and the
time it was read back.

The only real thing you can do is to read back the tape and look
for a couple of files with fairly high inode numbers for each file
system dumped.    If you can read them, you can assume the tape
is readable.

////jerry

> 
> -- 
> Anthony
> 



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