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Re: "serious issues with the 2.6 NFS server" (was: Re: Mail clustering)

--On March 21, 2007 12:26:45 AM +0100 Maximilian Wilhelm <max@rfc2324.org> wrote:

Am Tuesday, den 20 March hub Michael Loftis folgendes in die Tasten:


I'd ascertain what kind of load.  If it's I/O, NFS will likely make it
worse since NFS increases latency to disk by huge amounts.  Also I've
had  some serious issues with the 2.6 NFS server and have stayed on 2.4
for our  NFS server because of this.

Sorry for breaking up this thread, but I would be interested in these
issues, as we run some NFS servers on 2.4 and 2.6 machines and only
had trouble with them when hardware problems (SCSI RAID had trouble)

Could you tell me/us about the serious problems with NFS server on
linux 2.6?

Basically under high load the NFS server would very randomly start telling the clients permission denied on inodes. This was tested with debian stock 2.6.8 and kernel.org kernels 2.6.8, .9, and IIRC also .10. I was never able to adequately pin down exactly what was causing it, nor get it into a reliably reproducible state in a lab setup so I had to give up digging at it.

It was fine under low transaction rates, but once the rates started to pick up it was like there was a locking issue or a contention issue going on where the nfs kerneld would return errors randomly to the clients on directories they clearly had access to.

For a lot of people it may be fine, but under high load it fell apart. No real idea why which was the dismaying part. No OOPSes or any other misbehavior, just random nfs calls denied.

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