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Old 12-17-2008, 09:08 AM   #1
td3201
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Exclamation NFS Performance -- any ideas?


I have a pretty busy NFS server. There are a LOT of small I/O requests that come across. It is a cluster built on RHEL5 where I distribute each NFS export as a service across the cluster so it is in essence, an active/active cluster. Each export is ext3. Here is one of the mount points being shared out:
/dev/mapper/vg_data01a-lv_data01a on /data01a type ext3 (rw,noatime,nodiratime,data=writeback,commit=30)

I believe these to be optimum settings for performance, someone correct me if I am wrong.

I am starting 256 nfsd processes on each node. Here are the client mount settings:
omadvnfs01-nfs-h:/data01h /data01h nfs defaults,rsize=32768,wsize=32768 0 0

Here are some tests that drew me to NFS performance:

WRITING TO ISCSI DISK
[root@omadvnfs01b data01h]# time dd if=/dev/zero of=foo bs=16k count=16384
16384+0 records in
16384+0 records out
268435456 bytes (268 MB) copied, 0.547895 seconds, 490 MB/s

real 0m0.578s
user 0m0.004s
sys 0m0.540s
READING FROM ISCSI DISK
[root@omadvnfs01b data01h]# time dd if=foo of=/dev/null bs=16k
16384+0 records in
16384+0 records out
268435456 bytes (268 MB) copied, 0.142407 seconds, 1.9 GB/s

real 0m0.144s
user 0m0.008s
sys 0m0.135s


WRITING TO NFS EXPORT
[root@omadvdss01a data01h]# time dd if=/dev/zero of=foo bs=16k count=16384
16384+0 records in
16384+0 records out
268435456 bytes (268 MB) copied, 9.48628 seconds, 28.3 MB/s

real 0m14.394s
user 0m0.004s
sys 0m0.408s

READING FROM NFS EXPORT
[root@omadvdss01a data01h]# time dd if=foo of=/dev/null bs=16k
16384+0 records in
16384+0 records out
268435456 bytes (268 MB) copied, 4.03699 seconds, 66.5 MB/s

real 0m4.039s
user 0m0.007s
sys 0m0.302s


You can see the huge difference from direct I/O to the disk vs. nfs. I would like to close this gap a bit somehow. Any ideas?
 
Old 12-26-2008, 11:10 AM   #2
michaelk
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Please post your thread in only one forum. Posting a single thread in the most relevant forum will make it easier for members to help you and will keep the discussion in one place. This thread is being closed because it is a duplicate.

continue here:
http://www.linuxquestions.org/questi...e-help-691731/

If you feel that your question is in the wrong forum please ask a mod to move it instead of starting a new thread.
 
  


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