Hi Sven,

Can you show us the contents of /etc/exports on your head node?

I've had a similar problem in the past and managed to get better
write speeds by adding 'async' to my exports options (have a look
at `man exports`).

Hope this helps!

Regards,
Andreas Roussos
Systems Administrator
Operating Systems Group
University College London

Sven Sternberger wrote:
> 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