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From: "Jonathan M. Bresler" <jmb>
Message-Id: <199706190129.SAA24820@hub.freebsd.org>
Subject: Re: dump/restore with compression
To: ahd@kew.com (Drew Derbyshire)
Date: Wed, 18 Jun 1997 18:29:55 -0700 (PDT)
Cc: freebsd-hackers@FreeBSD.ORG, jmb@FreeBSD.ORG, brandon@ice.cold.org,
        freebsd-questions@FreeBSD.ORG, nate@mt.sri.com
In-Reply-To: <199706190058.UAA05638@pandora.hh.kew.com> from "Drew Derbyshire" at Jun 18, 97 08:58:43 pm
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Drew Derbyshire wrote:
> 
> > ps.	dont use compression.  if the data is valuable enough to backup
> > 	its valuable enough to backup reliably.
> 
> This implies compression is not reliable.  I can't say much for
> UNIX backups, but in general I've never had hardware or software
> compression screw up worse than any other hardware/software
> combination.

the danger with compression is that a single bit error can
destory the entire backup.  (note the _can_ it does not have to
be this way.  block compression in place of streaming compression
may not fail catastrophicly.

> I believe in compression because it encourages backups by reducing
> the media needed, cutting both media cost and time spent swapping
> volumes.  Less media per megabyte up also reduces the chances of
> an I/O error on media, so compressed backups can be more reliable
> than uncompressed.

get a tape backup device that can store everything.
you dont have to do a level 0 every night ;)

> 
> Like anything to do with backups, test and then test again.

Amen brother!