The problem
The NFS datastore I recently created to hold the virtual machine backups from my home ESXi server showed as “inactive” upon a recent server reboot. This was unexpected but, after some Googling, definitely not unusual. A second reboot (why not?) still did not restore the connection. I needed to find a proper solution to this problem.

My solution
Research pointed me toward the Advanced Software settings in VSphere. Under NFS I changed the following three settings:

I based these values on EMC and NetApp recommendations, except I went crazy with the NFS.HeartbeatTimeout; they only recommend 5. I went with a larger value as my NFS share is much slower than these vendor’s fine products.

These values work as such (cribbed from this post):

• Every “NFS.HeartbeatFrequency” (or 12 seconds) the ESXi server checks to see that the NFS datastore is reachable.
• Those heartbeats expire after “NFS.HeartbeatTimeout” (or 20 seconds), after which another heartbeat is sent.
• If “NFS.HeartbeatMaxFailures” (or 10) heartbeats fail in a row, the datastore is marked as unavailable (“inactive”).

It appeared that ESXi stopped trying to connect to the NSF share before the physical connection was even available. By upping the low defaults, this appears to have corrected the issue. Four reboots and the datastore is still available.