rsync - Oct 2005 - Rsync - slow performance problem...

Hi,

I am running rsync (rsync-2.6.3-1) on CentOS 4 (2.6.9-11.EL).

I notice that the performance is pretty slow ranges between 2 and 6
MB/s.

The command that I use from a remote machine to this, the archiving
host, is:

rsync -avz -e ssh ./dir archsrv:/archive/DATA


An investigation with top shows that the system is cpu bound rather than
IO bound and that the sshd process is consuming 75% of the CPU compared
to the rsync process which uses about 25%.

Why is ssh using so much CPU? It seems wrong to me. I would expect rsync
to be using most as it has to do compression.

Any Ideas?

Best Regards
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On Tue 04 Oct 2005, Gary Mansell wrote:
> I notice that the performance is pretty slow ranges between 2 and 6
> MB/s.
> 
> The command that I use from a remote machine to this, the archiving
> host, is:
> 
> rsync -avz -e ssh ./dir archsrv:/archive/DATA
> 
> 
> An investigation with top shows that the system is cpu bound rather than
> IO bound and that the sshd process is consuming 75% of the CPU compared
> to the rsync process which uses about 25%.
> 
> Why is ssh using so much CPU? It seems wrong to me. I would expect rsync
> to be using most as it has to do compression.
ssh has to do encryption, which is pretty CPU-intensive stuff.
You can tell ssh to use an encryption method that is less CPU-intensive,
such as arcfour; your command would look like this:

    rsync -avz -e 'ssh -c arcfour' ./dir archsrv:/archive/DATA

Alternatively, if security permits, use an rsync daemon.
> [snip silly disclaimer]
These are useless if writing to a mailing list... and probably useless
anyway.


Paul Slootman