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: …