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Message-ID: <40F36FD4.B3C75A45@dessent.net>
Date: Mon, 12 Jul 2004 22:15:00 -0700
From: Brian Dessent <brian AT dessent DOT net>
Organization: My own little world...
MIME-Version: 1.0
To: cygwin <cygwin AT cygwin DOT com>
Subject: Re: rsync very slow, but not a network issue
References: <40F2CE78 DOT 7030109 AT alexisgallagher DOT com> <40F2DD8B DOT 5080406 AT x-ray DOT at>
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Reply-To: cygwin AT cygwin DOT com

Reini Urban wrote:

> > When the file is alredy there, rsync reports a speedup of about 70.
> > (When the file is not already there, the speed up is 1, of course.) I am
> > running rsync over ssh with pre-generated keys installed in my .ssh
> > directories.
> 
> This is a binary MP3.
> rsync (as diff) is not good in checking binary diffs.
> Please try it with a typical text file, where the patch
> is smaller than the source.

That is not correct at all, and rsync would be much less useful if it
were true.  rsync works with arbitrary binary data just as well as it
does with text.  It has no conception of 'lines' or any other type of
delimited text.  All it does is split up the file into fixed-length
chunks and calculates a rolling checksum of each of these.  It does not
use anything resembling 'diff' or 'patch'. 

http://rsync.samba.org/tech_report/node2.html

Brian

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