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:
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