vCenter High Availability (VCHA) is the new feature introduced in vSphere 6.5 which is available with only VCSA deployment. It is a multi node architecture with active passive configuration plus a witness node. It is actually designed to reduce downtime during vCenter failures.
Soon after the VCHA is configured, a drs rule is created ensure that both active and passive never reside in the same host for better resiliency.
When VCHA configuration is completed, only the active VC will have an active management interface. VCHA network is created in all 3 nodes (2 VC’s and 1 witness) for private communication. Replication just happens between active and passive nodes, whereas witness is just a light version clone of active node that provides the quorum to protect from a split-brain situation. One of the key note of VCHA is, it requires only single vCenter license.
VCHA topology can be configured with vCenter setup with an embedded PSC or external PSC,
Embedded PSC: In this case, all PSC related services are also cloned during the process of VCHA configuration. After the configuration is completed, VCHA starts replicating Active to Passive node including PSC data, but the services and PSC data are available in passive node.
Single PSC: It is possible to configure vCenter(s) with single PSC, but this setup is potentially single point of failure.
Two PSC’s with load balancer: For production environment with large number of hosts, it is always a good idea to have load balancer for PSC’s.
VCHA is very easy to setup and whole configuration can be completed using vCenter web client. steps as given below: