[CentOS] Help needed with NFS issue

Thu Apr 19 20:05:30 UTC 2012
Steve Thompson <smt at vgersoft.com>


Many thanks to everyone who commented on this issue. I believe that I have 
solved it.

It turns out that the number of nfsd's that I was running (32) was way too 
low. I observed that adding more nfsd's when NFS was hung always caused 
the hang to go away immediately. Now I am in the tuning stage where I'm 
adding more nfsd's until there are no more hangs. I am up to 172 of them 
now, and the hang frequency has decreased by about a factor of six. 
Evidently my workload has changed when I wasn't looking closely enough. 
I'll probably end up with about 256 nfsd's.

For the sake of completeness, here's how to change the number of nfsd's on 
the fly:

 	echo 172 > /proc/fs/nfsd/threads

and, of course, edit /etc/sysconfig/nfs to change RPCNFSDCOUNT to set the
value for the next boot.