Just wanted to give my readers a heads up that there appears to be a bug with vSphere 5.5 U1 that impacts any NFS connected storage and can cause random disconnects. The timing of this is a coincidence that it comes right on the coat tails of my previous article Hardware Fails, Software Has Bugs and People Make Mistakes – Usually You Get All At Once! During the disconnects VM’s will appear frozen and the NFS datastores may be greyed out. This appears to impact all vendors and all environments on 5.5. U1 accessing NFS. UPDATED: There is a public KB on this problem from VMware: KB 2076392 – Frequent NFS APDs after upgrading ESXi to 5.5 U1, and VMware is working on it. According to the KB you may experience blue screens of death in Windows, and read only file systems in Linux. I’ve also experienced kernel panics and reboots in Linux as a result of this bug.
NetApp was first to report it. The recommendation from most vendors (Including Nutanix as per Field Advisory FA-17) at this point is to not upgrade to vSphere 5.5 U1 and stay on vSphere 5.5 GA. If you have upgraded to 5.5 U1 then you may need to downgrade back to 5.5GA. I have tested and been able to reproduce this problem on vSphere 5.5 U1 on two completely different vendors systems.
For further information you can see Datacenter Dude Nick Howell’s article – NFS Disconnects in VMware vSphere 5.5 U1, and keep an eye out on the VMware knowledge base article. It is recommended you subscribe to the KB article so that you are made aware of any updates.
[Updated 12/06/2014] There is an updated KB article regarding the NFS Disconnection Bug – KB 2076392, and VMware has issued a patch to correct the problem. vSphere 5.5 Patch 04. It is strongly recommended that you apply patch 04 if you use NFS and wish to leverage the fixes and improvements in vSphere 5.5 Update 1.
If you’re using block based storage, i.e. VMFS, and a EMC VMAX then you might want to read Cormac Hogan’s article with regard to a situation with VMAX, VAAI and the Unmap command.
This post appeared on the Long White Virtual Clouds blog at longwhiteclouds.com, by Michael Webster +. Copyright © 2014 – IT Solutions 2000 Ltd and Michael Webster +. All rights reserved. Not to be reproduced for commercial purposes without written permission.