vCLS Agent VMs - Host Maintenance

[rellan1]

Hi All.

I want to put a host in maintenance mode, but it has a vCLS Agent VM running on it.  This DRS is set to manual on this cluster.  Do I simply vmotion the agent VM and pass through the warning message and move the agent VM back when I'm done the work on the host?

DR

 

[mbufkin]

You should be able to migrate to a different host. You can override default vCLS VM datastore placement. https://docs.vmware.com/en/VMware-vSphere/7.0/com.vmware.vsphere.resmgmt.doc/GUID-6C11D7F9-4E92-4EA8-AA63-AABAD4B299E7.html 

[mbufkin]

Here is some information about vCLS.

https://docs.vmware.com/en/VMware-vSphere/7.0/com.vmware.vsphere.resmgmt.doc/GUID-96BD6016-4BE7-4B1C-8269-568D1555B08C.html

[rellan1]

I believe I found the answer.

https://kb.vmware.com/s/article/80472

Half-way through this article:

"

vCLS during infrastructure maintenance

• Cluster compute maintenance (more details here - Automatic power-off of vCLS VMs during maintenance mode)
  • When there is only 1 host - vCLS VMs will be automatically powered-off when the single host cluster is put into Maintenance Mode, thus maintenance workflow is not blocked. 
  • When there are 2 or more hosts - In a vSphere cluster where there is more than 1 host, and the host being considered for maintenance has running vCLS VMs, then vCLS VMs will be migrated to other hosts if there are free resources and if they have storage connectivity (shared storage). If these VMs cannot be migrated for the lack of free available resource on other hosts or if these VMs are placed in a local datastore, then these VMs will be powered off automatically to give preference to the host Maintenance Mode operation. As stated before, vSphere DRS for a cluster will not be functional where there is not at least 1 vCLS VM running in that cluster.
  • If you are decommissioning a cluster, then you have to put all the hosts into Maintenance Mode prior to deleting the cluster for proper clean-up of vCLS VMs. If you delete the cluster without placing the hosts in Maintenance Mode, there will be stale vCLS VMs running inside the hosts causing issues when these hosts with running VMs are added back to a new cluster. 
  • Disconnect Host - On the disconnect of Host, vCLS VMs are not cleaned from these hosts as they are disconnected are not reachable. New vCLS VMs will not be created in the other hosts of the cluster as it is not clear how long the host is disconnected. When disconnected host is connected back, vCLS VM in this disconnected host will be registered again to the vCenter inventory. If a disconnected host is removed from inventory, then new vCLS VMs may be created in other hosts of the clusters if Quorum is not reached. 
  • Datastore maintenance. For more information, see Impact of vSphere Cluster Services on storage workflows (80483)."

[mbufkin]

Perfect. Looks like you got your answer.

[dstadelmann]

Hi  

when you enable maintenance mode on the host the cluster will automatically move (also without DRS enablement) to another host. If you try to manually move it you will get a prompt referring to a KB.

 

recommendation: Make sure you set the datastore selection on the cluster configuration to productive datastore, so the vcls vms are not created on host local storage. This option is available starting from update 3c as far as I rember.

Please kudo and marks as solved, when your question is answered.

daniel

[padapa2022]

 Even with the DRS set to Manual, you can just put the host in maintenance mode and the vCLS vm will move to another host in the cluster with no issues.

 

Pradeep Adapa