As we know vSAN 6.6 architecture has been enhanced and networking requirement i.e. multicast has been replaced by unicast for all host membership activities. In unicast, vCenter maintains the host membership list as compare to earlier versions where CMMDS was playing vital role.
vSAN 6.6 & later has released a cluster health check named vCenter state is authoritative. During normal operations, ESXi regards vCenter as state of truth & vCenter pushes the updated membership list to all the hosts part of vSAN cluster. With the help of which all the ESXi hosts are aware about their unicast neighbors.
Now, this test is very useful in scenarios where vCenter goes down or restore VC from backup or you deploy new vCenter Server for some reason.
- If we are able to recover the VC from failure, then there should be no issues in host membership lists as VC will have updated membership entries
- At times, when we restore the VC from backup, mostly it will have outdated membership details and when hosts is connected back to vCenter, VC will push the outdated list which may affect vSAN behavior. Hence, this test will prevent VC to push unicast details to hosts.
- New vCenter deployment also run into same behavior as VC does not have updated membership details of vSAN hosts. In this case also, VC authoritative test will fail
Note, in 2 & 3 scenario once vSAN hosts are connected back to VC they will be in network partition state and when you run below command you won’t see unicast neighbors (obviously because VC hasn’t pushed updated membership to hosts)
localcli vsan cluster unicastagent list
To resolve this issue, you can simply click on update ESXi configuration and all the hosts membership lists will be updated with vCenter. Now, vCenter and hosts are in sync & test state is green.
You can run check unicast members updated as shown below:
Click on Monitor vSAN ⇒ Health ⇒ Expand cluster ⇒ vCenter state is authoritative
Click on Update ESXi configuration
Note: If still VC state is out of sync and host membership list is not updated. You must manually put unicast neighbor entries in each host. Please involve VMware Support for further investigation.
If you like this blog post, please feel free to share with your friends on social media.
Thanks for reading!!