From mboxrd@z Thu Jan  1 00:00:00 1970
From: Valdis.Kletnieks@vt.edu
Subject: Re: duplicate files and recent changes
Date: Thu, 06 Jun 2002 13:58:15 +0000
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On Thu, 06 Jun 2002 13:25:05 +0400, Oleg Drokin said:

> But MD5 may be identical for different files.

Only a 2**128 chance of that.  If you know a way to force a hash collision
more frequently than that, the crypto world wants to hear from you.. ;)

> Also this buys you nothing.
> You write file in chunks, once file is identical to other file,
> one of the files deleted. Looks like just more extra work (but some saved
space
> of course).

A much more productive way to save space is file-system compression.  AIX
supports LZ-compressing each 4K block and then only saving as many 512 byte
fragments as actually needed.  It's a big win - /usr (even with all the
binaries)
needs about 30% less space, and I've seen over 50% for file systems with
source trees in them...
--
                    Valdis Kletnieks
                    Computer Systems Senior Engineer
                    Virginia Tech


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