What may be a cause for failure to unmount an NFS datastore?
A.
It has active snapshot files.
B.
It is being used for High Availability (HA) heartbeat.
C.
It is part of a Cluster.
D.
It is managed by Distributed Resource Scheduler (DRS).
Explanation:
vSphere HA heartbeating does not prevent you from unmounting the datastore. If a datastore is used for heartbeating, unmounting it might cause the host to fail and
restart any active virtual machine. If the heartbeating check fails, the vSphere Client displays a warning.
https://pubs.vmware.com/vsphere-50/index.jsp?topic=%2Fcom.vmware.vsphere.storage.doc_50%2FGUID-1B56EF97-F60E-4F21-82A7-
8F2A7294604D.html
A
https://communities.vmware.com/thread/399071
C
A is the correct answer. B,C and D are mentioned as pre-requisites before unmounting the datastore, but it doesn’t necessarily cause to fail the operation:
https://kb.vmware.com/s/article/1037393