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.

http://lime-technology.com/forum/index.php?topic=27604.msg243305#msg243305

http://lime-technology.com/forum/index.php?topic=27874.msg246978#msg246978

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.

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