vCenter HA Gotcha’s (vSphere 6.5)

There are a few gotcha’s and known issues that I have found with vCenter HA. Hopefully the following will be of use and avoid the need to engage VMware Support to resolve.

For more on VCHA please see my previous post which also includes short videos of both deployment methods.

Gotcha 1: Anti-Affinity Rule

If you have a DRS Cluster, during the Basic (or Automatic) VCHA deployment, a VM Anti-Affinity rule will be automatically created to keep the three VMs on separate ESXi Hosts to maximise availability of the VCHA Cluster.

If you have, for  whatever reason a single node DRS Cluster (maybe it’s a lab) your deployment of VCHA will fail as the “Peer” node will not be able to be powered on. The DRS rule doesn’t get created until after the “Peer” node clone is complete and before the split second in which the VM is told to power on.

If you can’t turn off DRS on this one node cluster, or add additional ESXi Hosts you’ll have to let VCHA fail to deploy once and then you can go an disable the DRS rule. Don’t delete it, as it will just get re-created, just disable it.

Now when you go to try deploy VCHA again on the single node DRS Cluster, the “Peer” and “Witness” VMs will not be bound by the DRS rule and will power on and form the VCHA Cluster.

Update: There appears to be an advanced setting you can set to false to bypass this automatic DRS rule creation. See a post by William Lam for more

http://www.virtuallyghetto.com/2016/11/how-to-enable-vcenter-server-high-availability-vcha-in-vsphere-6-5-wsingle-esxi-host.html

Gotcha 2: Snapshots / ISOs

When attempting to automatically configure VCHA you might encounter the error message:

The operation is not allowed in the current state.
vCenter HA does not support an Active node having disks on more than one datastore.

Apart from what the message says about having disks on more than one datastore there are two other reason why this error may be seen.

  1. Ensure No Snapshots exist on the VCSA.
  2. Ensure CD/DVD is set to Client Device.

(Just having an ISO disconnected is not enough)

Gotcha 3: Restoring from backup

If you restore a VCSA 6.5 from backup using the built-in backup/restore function, certain tasks will not immediately work, namely enabling VCHA.

After you restore a VCSA 6.5 from backup and try to enable VCHA you may hit one of the following errors:

Basic Deployment:

Cannot find a network adapter for the vCenter Server management network (NIC0) on the vCenter Server Appliance guest OS. Once available, the first guest OS network adapter will be selected. Use Edit VM settings to add a network adapter.

Advanced Deployment:

No static IP address is configured on the guest OS network interfaces. vCenter HA requires static IP addresses. Go to System Configuration to add a static IP address on the networks adapters.

The reason is that during the restore of the VCSA 6.5, the VAMI service does not get issued a full restart after the restored data is consumed. To resolve this, either reboot the VCSA or simply run the following command from the BASH Shell of the VCSA

service vami-lighttp restart

This issue may also manifest itself in you not being able to enable/disable SSH of the VCSA via the vSphere Web Client.

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