Hello!

I'm looking for a way to improve our nfs performance.
We recently updated a small cluster (16 nodes). The nodes
mount a share via nfs.

I use nfs3 over tcp. I checked the disk write speed on the server
(450mb/s) and the network thruput (980 mb/s). I tried udp, the deadline
scheduler and large tcp buffers.

SElinux and auditd is disabled, the server (Dell2950 w 8GB memory,PERC5)
and my testnodes (Dell 1950 w 8 GB memory) both run 64bit SL5.

What I see is >> always << ~20MB/s writing speed (reading is
about 90mb which looks ok). I can see the 20MB/s also in
iostat.

Device:         rrqm/s   wrqm/s   r/s   w/s    rkB/s    wkB/s avgrq-sz
avgqu-sz   await  svctm  %util
sdb               0.00  6511.63  0.00 83.39     0.00 25892.36   621.00
143.20 1552.83  11.96  99.70

My write test is:
time dd if=/dev/zero of=./testme bs=1024k count=1000

I would expect that the write speed is higher. So any advice or
explanation would be helpful

best regards!

sven