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Date: Tue, 26 Feb 2002 11:15:09 -0700
From: Andreas Dilger <adilger@turbolabs.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Rose, Billy" <wrose@loislaw.com>,
        "'Martin Dalecki'" <dalecki@evision-ventures.com>,
        Mike Fedyk <mfedyk@matchmail.com>, linux-kernel@vger.kernel.org
Subject: Re: ext3 and undeletion
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On Feb 26, 2002  10:00 -0800, H. Peter Anvin wrote:
> Rose, Billy wrote:
> > My company can tolerate 0% loss of data (which is why I raised this issue).
> 
> There is no such thing as 0% loss of data.  You can get some amount of 
> security with backups, snapshots (really useful!) or undelete, but you 
> can *NEVER* guarantee 0% loss of data... consider the case when a 
> (l)user overwrites (not just deletes) a newly created file.

Snapshots at the filesystem level could handle the overwrite case.

However, even then it cannot be 0% loss of data, unless you have snapshots
for _every_ write of the file, which would quickly become prohibitive in
space usage (think autobackup from an editor on a large file).  Sometimes
people just have to learn from their mistakes...

Cheers, Andreas
--
Andreas Dilger
http://sourceforge.net/projects/ext2resize/
http://www-mddsp.enel.ucalgary.ca/People/adilger/

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