RHEV Host went to 'non-operational' after losing connection to NFS storage domain

Issue

• RHEV Host went to 'non-operational' after loosing connection to NFS storage domain
• RHEV Host lost connection to domain - see errors below:

"VM [vmname] is down. Exit message Lost connection with qemu process."

• Error:

Traceback (most recent call last):
  File "/usr/share/vdsm/storage/task.py", line 857, in _run
  File "/usr/share/vdsm/logUtils.py", line 41, in wrapper
  File "/usr/share/vdsm/storage/hsm.py", line 2955, in getVolumeSize
  File "/usr/share/vdsm/storage/volume.py", line 322, in getVSize
  File "/usr/share/vdsm/storage/fileVolume.py", line 459, in getVSize
  File "/usr/share/vdsm/storage/remoteFileHandler.py", line 290, in callCrabRPCFunction
Exception: No free file handlers in pool