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Consider I have a large file on my nfs server. The server and my desktop is connected by 100mbps network. If I mount a directory on my desktop and then try to copy a big file to local fs I have speed about 3.5MB/s. But if I try to tranfer the same file using wget (nginx on server side) I have about 6.1MB/s.

Why it is so? Why nfs preformance is so bad? And the most important, how to improve this one.

I have linaro (ubuntu clone for arm systems) on server and opensuse 11.4 on client, nfs is version 4.

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Run top while doing a NFS trasfer; notice any spikes in CPU or Memory usage? – Chris S Mar 26 '12 at 0:36

AFAIK NFS uses UDP by default -- have you tried mounting the export over TCP instead (proto=tcp)? You could also try changing the rsize value. This page has some information on NFS performance tuning.

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Most NFS implementations use TCP by default; but UDP is faster anyway. rsize should match the packet size (less header), so it shouldn't be changed unless his MTU is not 1500. – Chris S Mar 26 '12 at 0:34

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