On Mon, Jun 21, 2010 at 4:38 PM, Nataraj <incoming-centos at rjl.com> wrote: [...] > Well, it's been a long time since I've done troubleshooting on large NFS > networks, but here's an idea... > > Are you seeing any kind of packet loss/retransmissions? Take a look at > netstat -s. When I last did this work it was with NFS over udp, but I > think retransmitted packets will cause more performance loss with large > packet sizes. I used to find machines with broken ethernet interfaces > that would cause these kinds of problems. > > Nataraj Thanks guys for the feedback. I've done more tests : There are very very few retransmits (less than 0,01%) so I don't think that's what happening. The client still seems to be "waiting" for something between requests, very strange. On some servers this behavior returned despite rsize being set to 32k, I had to set it to 8k to get reasonnable throughput. So there's definitly something fishy going on. This has been reported on over 20 machines, so I don't think it's faulty hardware we're seeing. Any thoughts, ideas on how to debug this ? Best, Alex