If you face APD’s in your environment you can follow the KB below to possible improve the situation.
When using NFS datastores on some NetApp NFS filer models on an ESXi/ESX host, you experience these symptoms:
* The NFS datastores appear to be unavailable (grayed out) in vCenter Server, or when accessed through the vSphere Client
* The NFS shares reappear after few minutes
* Virtual machines located on the NFS datastore are in a hung/paused state when the NFS datastore is unavailable
* This issue is most often seen after a host upgrade to ESXi 5.x or the addition of an ESXi 5.x host to the environment but can also occur in vSphere 6 environment.
NFSLock: 515: Stop accessing fd 0xc21eba0 4
NFS: 283: Lost connection to the server 192.168.100.1 mount point /vol/datastore01, mounted as bf7ce3db-42c081a2-0000-000000000000 (“datastore01”)
NFSLock: 477: Start accessing fd 0xc21eba0 again
NFS: 292: Restored connection to the server 192.168.100.1 mount point /vol/datastore01, mounted as bf7ce3db-42c081a2-0000-000000000000 (“datastore01”)
Additionally VMware released a new Patch for ESXi 5.5 / 6 which contains improvements of the NFS implementation which should make the ESXi more resilient to APDs.
Besides running the latest version of ESXi it is highly recommended to apply the NetApp NFS vSphere recommendations.