[Lustre-discuss] Line rate performance for clients

Peter Kjellström cap at nsc.liu.se
Mon Aug 1 05:52:07 PDT 2011

> > On 2011-07-29, at 11:33 AM, Brock Palen wrote:
> >> I think this is a networking question.
> >> 
> >> We have lustre 1.8 clients with 1gig-e interfaces that according to
> >> ethtool are running full duplex.
> >> 
> >> If I do the following:
> >> 
> >> cp /lustre/largeilfe.h5 /tmp/
> >> 
> >> I get 117MB/s
> >> 
> >> If I then use globus-url-copy to move that file from /tmp/ to -> remove
> >> tape archive I get 117MB/s
> >> 
> >> If I go directly from  /lustre -> archive  I get 50MB/s,
> Its just when the client is reading form lustre and sending the data out at
> the same time that I only get 50MB/s.
> Does that make sense?  Is it even right for me to expect that I could
> combine the performance together and expect full speed in and full speed
> out if I can consistently get them independent of each other?

Can your setup do wirespeed full duplex in the simplest case (never mind with 
lustre)? I'd try iperf or something similar before investing too much time 
looking for "lost" performance in higher layers.

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