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Subject: Re: ext4 features
From: Trond Myklebust <trond.myklebust@fys.uio.no>
To: Bill Davidsen <davidsen@tmr.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>, Theodore Tso <tytso@mit.edu>,
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Date: Thu, 06 Jul 2006 22:30:47 -0400
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On Thu, 2006-07-06 at 22:15 -0400, Bill Davidsen wrote:
> Trond Myklebust wrote:
> 
> >Nobody gives a rats arse about backups: those are infrequent and
> >can/should use more sophisticated techniques such as checksumming.
> >
> Actually, those of us who do run production servers care vastly about 
> backups. And beside being utterly unscalable (checksum 20 TB of files 
> four times a day to find what changed???), you would have to remember 
> the checksums for all those files.

It is trivial to check if your last backup of the file was started
within 1 second or so of the last change made to the file, in which case
your backup program needs to perform a more thorough check. That sort of
thing is possible when you are talking about a daily (or even hourly)
backup.

Cheers,
  Trond