I recently ran across a problem with XenServer 6.2 when connecting to my Unraid on NFS. It kept dropping the NFS connection but I couldn’t determine why. I thought it might be Xen related and reinstalled straight Ubuntu 12.04 instead. However, I started having the same problem with Ubuntu with mounted NFS shares. It would seem to age them out. Luckily, Ubuntu gave me some more info and would throw up a message about “Stale NFS File Handles”. A little more digging and I come across a couple of things on the Unraid user forum that point to Unraid being the problem.
Using both of these I was able to get a stable connection from Ubuntu to Unraid. I set the tunable in the Unraid NFS settings to -1 and added the lookupcache option on Ubuntu. I didn’t do any performance testing.
Now, I’ve tried going back to XenServer hoping that the Unraid tunable would be enough to fix the issue in Xen. It’s not. Still had a loss of connectivity to the Unraid NFS share after a couple of hours. I’ve just now gone into the Xen settings per this post: http://likerabbits.blogspot.com/2009/09/xenserver-performance-tweaks.html and added the noac option.
We’ll see how it goes over the next several hours.
Updated: No luck with adding lookupcache=none and noac to the basic options. It still croaked after 15-20 minutes. I found another reference to checking the /etc/mtab file and saw some more options, including one for actimeo. I’m trying it with that eliminated to see if it makes a difference.
Second update: commenting out actimeo might have worked. I’m only 2 hours in but I think this is longer than previous failures. I’ll create a new post with the necessary changes, if this ends up working.