Chapter 2 – HA requirements for VSAN enablement

During the initial VSAN configuration, we went through the process of disabling and then re-enabling vSphere HA on the VSAN cluster. This step was necessary due to changes in how vSphere HA works in VSAN-enabled clusters.

HA behavior in non-VSAN clusters

In non-VSAN infrastructures, vSphere HA uses the host management network to determine network isolation. The hosts communicate with each other over the management network and the hosts communicate with the default gateway periodically. If this communication fails, vSphere HA determines that the ESXi host is isolated and will take corrective action.

vSphere HA datastore heart beating adds another layer of communication via the shared datastores but does not change the fundamental network-related assumptions.

HA behavior in VSAN clusters

Within a VSAN cluster, however, certain HA assumptions must change. As opposed to the typical case where host manageability is the paramount networking consideration...