How to Powerdown vCLS VMs

vCLS is a collection of multiple VMs acting as the backbone for all clustering services. These VMs pop up all the time when new ESXi hosts are being added so these can’t be vMotioned off or powered off , so let’s see how this is done.

Distributed Resource Scheduling ( DRS ) has been there for every version of vCenter and it has the sole responsibility to ensure even placement of VM’s in a cluster based on the load scenarios on the ESXi hosts. Thus if vCenter is unavailable, it simply means that DRS won’t function. In order to address this issue of vCenter unavailability, a cluster of tiny virtual appliances that can just do the clustering duties to take them out of vCenter’s hands and improve availability was introduced and these are known as the vSphere Cluster Service VMs.

These cluster VMs are tied to hosts via anti-affinity DRS rules and are enabled by default to maintain the DRS health of the cluster. They can’t be powered off by default and if we attempt to do so, they will automatically be powered on.

So if we do have to remove these VMs during a vSAN Shutdown for example, we have to disable the vSphere Clustering Service to automatically remove the DRS VMs and this is basically what’s known as turning on VMware Retreat Mode.

In version 8.0 U2 and above, retreat mode can be enabled or disabled via the UI itself but on the previous versions, this needs to be done from the CLI or through an advanced setting at the vCenter level targeting a specific cluster. To turn on retreat mode on a cluster, open the vCenter UI, select the cluster and look for the “domain-cXXX” section in the vCenter URL