Now that the VSAN cluster is created and validated, we are ready to re-enable vSphere HA. This process is the same as it was prior to the introduction of VSAN.
From the vSphere Web Client, navigate to: Home | Hosts and Clusters | Datacenter | Cluster | Manage | Services | vSphere HA.
Click on the Edit… button:
In the subsequent menu, check the Turn ON vSphere HA checkbox.
Select any monitoring, admission control, and Datastore Heartbeating options, as per your infrastructure and administrative needs.
Click on OK:
This process can take some time. Monitor the progress in the Recent Tasks pane and investigate any HA-related failures as needed.