rsync very slow, but not a network issue

Reini Urban
Mon Jul 12 18:50:00 GMT 2004

Alexis Gallagher schrieb:
> I am finding that rsync+ssh is giving extremely slow file transfers. But 
> this slowdown is hitting not when it needs to send data over the 
> network, but when it applies the rsync algorithm which is supposed to be 
> faster than sending all the data over the network. This is very puzzling.
> For a benchmark, I tried transfering a 5.4 MB mp3 file three different 
> ways. Here were my results, as reported by 'scp -v' and 'rsync 
> --progress --stats':
>    scp: 311000 B/s
>    rsync (file not there): 309000 B/s
>    rsync (file already there): 741 B/s
> 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.
Reini Urban

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