> No errors that I can find, omsa doesn't obviously show anything as degraded.
Do you have a utility like the old megamgr that can get you controller stats? That will report actual disk errors that are seen by the RAID controller, which may not make it all the way through to the OS. > This only appears to be occurring under particular heavy load over NFS. I can > merrily run iozone against the array and the machine remains responsive, and > the performance looked reasonable. Do you mean that when there is a 'stall', you can still access the disk locally? In your original e-mail you suggested this wasn't the case. It's probably worth confirming which it is, because that would indicate it is either an NFS or a hardware issue. > I need to find a reliable way of triggering this behaviour. > > A looping once-per-second sync, made the machine reliably available, although > I suspect this was just treating the symptoms. This doesn't seem to suggest a hardware problem. It's possible that your disk caches are just set too large, and once it reaches a critical point they get flushed to disk, but because they're so big the disks can't keep up. Imagine if you had a 1GB writeback cache which suddenly the kernel decided needed to be flushed ASAP - that 1GB of disk write activity could cause all programs doing disk IO to stall for a few seconds until it was complete. If a once-per-second sync avoids the issue, I would suggest shrinking your disk writeback cache. Cheers, Adam. _______________________________________________ Linux-PowerEdge mailing list [email protected] https://lists.us.dell.com/mailman/listinfo/linux-poweredge Please read the FAQ at http://lists.us.dell.com/faq
