Once you have VSAN configured and enabled, you may find that the hosts are not communicating with each other properly. As VSAN is a distributed storage system, it depends on healthy, functional networking to work properly. If you have a cluster where not all nodes can communicate via both unicast and multicast IP, then one or more nodes will be in a different network partition from that of the other node(s). To work as expected, all VSAN nodes must be in the same network partition.
If the VSAN cluster is partitioned, you may notice one or more of the following behaviors:
The capacity of the VSAN Datastore is smaller than expected
You have experienced an HA failover event
One or more hosts report Host cannot communicate with all other nodes in the VSAN enabled cluster in vSphere Web Client: