vCenter 7 vCLS HA/DRS cluster VMs questions

  • 2 June 2021
  • 0 replies


Hello, all. We’re running vCenter 7 with AOS 5.15.x, and I’m learning about how VMware has now decoupled the DRS/HA cluster availability from vCenter appliance and moved that into a three VM cluster (the vCLS VMs).

In the interest of trying to update our graceful startup/shutdown documentation and code snippets/scripts, I’m trying to figure out how to handle these vCLS VMs. They reside on the Nutanix shared storage, so I obviously would like to shut them down before gracefully shutting down the Nutanix CVMs/ADSF cluster as well as ensure the CVMs are up and cluster is good before allowing them to power back on using that storage. Evidently, these vCLS VMs are very aggressive about powering back on or recreating themselves once deleted, so I’m a little unsure what to expect.

So with regard to powering back on the ESX hosts, I assume when I take them back out of maintenance mode the CVMs will be powered back on (or maybe I have to do that manually?), and after waiting a few minutes, I would SSH to one of them and issue the `cluster start` command to bring up the storage, but in the meantime I think these vCLS VMs are going begin attempts to start back up. They will apparently try to use shared storage as a preference and will try local storage if shared isn’t available.

In the timing of events when the CVMs are powering up and in some state of bringing the cluster up, do they present the NFS storage to the ESX hosts in such a way that the vCLS VMs might be able to start up on that storage and cause any problems, or is the NFS storage really not presented as available until cluster status is “UP” across the nodes? Also, I notice that each CVM has a ~200GB local datastore associated with it, and I know we were told by Nutanix professional services to never touch that of course, but could these cluster VMs attempt to use that storage if the shared storage weren’t available? What would happen in this case?

Obviously just looking for some answers to help flesh out this story, so thank you in advance for any tips or insight!

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