VMware vCenter High Availability (VCHA)

With the release of vCenter 6.5, a built-in native High Availability (HA) feature was introduced. This has been a long-awaited feature since the end of availability of vCenter Server Heartbeat since vCenter 5.x.

With the release of VCHA, I came across many times people asking how can we implement it?

There are a few articles from VMware that show some of the supported topologies. However, with the realize of vSphere 6.7 U2, the recommended vCenter Server deployment is with embedded PSC. In this case, we will just look at the topology that has an embedded PSC. This is welcoming since we have less component to handle and need not require a load balancer just to load balance PSC.

Let us go through some of the common questions been asked.

How many instances does VCHA deploy?
With VCHA, you would have three instances of vCenter namely: vCenter Server  (Active), vCenter Server (Passive), vCenter Server (Witness).

How many vCenter Server licenses do I need and which edition?
The licensing requirement for this case only needs one vCenter Server Standard license to utilize this feature without having to license all three instances.

In VCHA, the vCenter Server instance is of the same configured sizing for all three, can we resize the witness?
Yes. In the Basic configuration, this is done automatically for you. If you are doing in Advanced, you can change the vCPU and memory to 1 vCPU and 1 GB respectively.

Can I place the witness on a 3rd site?
Yes, you can but why do you need to. There is no strong value. The reason is VCHA is a local site availability to keep vCenter Server available at the local site and not a disaster recovery solution. It is not used for site failure purpose but local site component failure. Placing the witness to another site is not wrong but you added complexity when there is a breakage between the site where the witness lose connection to the main site. The bandwidth round trip time (RTT) requirement for the three instances between each other needs to be within 10ms. The recommendation is to place all three instance on different ESXi server in the same cluster or if you are worried on cluster outage, then across cluster within the same site.

Can the witness run as a physical server?
No. As VCHA instances are all preconfigured virtual appliance, it cannot be installed on a physical machine. VCHA is only available in the virtual appliance option so you cannot do your own installation.

Can the witness run on a standalone free ESXi hypervisor?
Yes, however, the free ESXi hypervisor does not have a license attached to it. Naturally, the witness will not have VMware support even though you have purchased support for the vCenter Server.

How to upgrade VCHA?
The easiest way is to destroy and upgrade the vCenter Server and deploy VCHA again. Refer to this article.

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