When you can’t reconnect to NFS share on your IX4-200D

In my home lab it sometimes happens that I lose power and then my Iomega IX4-200D will reboot. Often, the ESX hosts I run in my lab have trouble reconnecting to the NFS share on the IX4-200D which will cause my primary VMs to fail. Both my domain controllers, vCenter server, SQL Server and Exchange Server are on the IX4. Yes I know it is bad design to have both domain controllers on the same datastore, but hey… it’s a lab and I normally can live with this issue :-)

The strange thing though is that my ESX hosts have trouble reconnecting to this NFS share, even though my Windows machine can browse through the shared folders. When trying to reconnect from the command line, I received the following response:

[root@esx02 etc]# esxcfg-nas -a nfs-StorCent03 -o -s /nfs/nfs-StorCent03
Connecting to NAS volume: nfs-StorCent03
Unable to connect to NAS volume nfs-StorCent03: Unable to complete Sysinfo operation.  Please see the VMkernel log file for more details.

The vmkernel log shows:

May 26 16:51:26 esx02 vmkernel: 2:04:32:27.596 cpu3:4108)NFS: 149: Command: (mount) Server: ( IP: ( Path: (/nfs/nfs-StorCent03) Label: (nfs-StorCent03) Options: (None)
May 26 16:51:56 esx02 vmkernel: 2:04:32:57.933 cpu2:4108)WARNING: NFS: 946: MOUNT RPC failed with RPC status 13 (RPC was aborted due to timeout) trying to mount Server ( Path (/nfs/nfs-StorCent03)
May 26 16:51:56 esx02 vmkernel: 2:04:32:57.933 cpu2:4108)NFS: 160: NFS mount failed: Unable to connect to NFS server

After some testing it turns out that the IX4 has a DNS issue. Since both my domain controllers are down and these are my DNS servers, no DNS resolution can take place. However, in the IX4 tcp/ip settings control panel, the IP address of both domain controllers is used as DNS server. After removing these IP addresses, I could reconnect within a second.