NFS problem in the latest kernel (Was: [CentOS] MySQL issues with kernel-2.6.18-53.1.6.el5.x86_64.rpm)

Thu Jan 31 18:28:52 UTC 2008
nate <centos at linuxpowered.net>

Akemi Yagi wrote:

> This problem does not seem to be associated with specific hardware as
> implied in the original thread.  The person on the SciLinux mail list
> has Dell machines, and I was able to confirm the issue using custom
> built boxes.  I have added a note in the bug tracker at:
>
> http://bugs.centos.org/view.php?id=2635

Unrelated, but still kind of related, I'm only replying because of
how crazy I went trying to track it down. But I had major NFS client
issues on CentOS 4.5, specifically kernels after 2.6.9-55.ELsmp. Even
under pretty light load, after seemingly random periods of time NFS
write performance would go down 99.99999%. Read performance was fine.
Downgrade the kernel and it worked fine again. Eventually for servers
that ran our critical apps for NFS I just upgraded them to CentOS 5.1
and there is no problems there for us at least.

Spent several weeks researching the problem but never found a solution,
since it took so long to reproduce(up to 24 hours typically), testing
different configurations was very time consuming.

And no I haven't filed any bug reports or anything as I wanted to
try to narrow it down further to find the source before that. But
I ran out of time, and the kernel in CentOS 5.1 seems to work fine.
(migrated production systems to it about 6 weeks ago)

The newer kernel didn't/does not affect the NFS servers at all,
as they are all running CentOS 4.5 with 2.6.9-55.0.9.ELsmp, it's
purely a client-side issue.

(sorry, end rant :) )

nate