Re: transition RedHat-Debian
According to Drake Diedrich,
> On Wed, Sep 14, 2005 at 02:35:41PM +0900, Adam C Powell IV wrote:
> >
> > We've been over this a few times on this list before; some argued a
> > performance hit with ssh, others seem to think the hit is relatively
> > small. I personally use rsh on all of my group's clusters, noticed a
> > huge hit at startup with ssh but haven't characterized the long-term
> > impact. But these clusters are all firewalled, and so have never had
> > any problem (that I know of). This would of course be foolish on
> > net-exposed machines, unless you only allow rsh access to localhost.
>
> Just to add a concurring note, on our cluster I run the backups and several
> other bulk transfers using rsh rather than ssh. The maximum speed with ssh
> on our machines (starting to age now) is around 150 Mbps, pegging a CPU at
> each end. With rsh it's ~650 Mbps and isn't using most of a CPU. Startup
> delay for ssh is also a lot higher (qualitatively, I notice ssh startup
> times but not rsh startup times). NFS is higher still, but only if you're
> doing large files or multithreaded. For small files tar/rsync/... over rsh
> is faster...
Have you tried ...
ssh -o Cipher=none -o Compression=no
... ? I don't do any heavy duty transfers on secure networks
myself, but it seems like it'd give you the performance
benefits of rsh with only one of its drawbacks (encryption)
In fact, you might even get better performance with light compression...
ssh -o Cipher=none -o Compression=yes -o CompressionLevel=1
...if your transfers involve plaintext or sparse files or
other low-entropy data.
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