I would like to try to add a Server 2012 Hyper-V server to my current cluster,
Currently 2 server 2016 Hyper-V servers clustered.
I need to be able to add the third because I have to do some reconfiguration on the cluster, I have to be able to Live Migrate the couple of VM's to the new 2012 server take both 2016 servers out of the cluster fix them and then add them back.
When I try to add the Server 2012 server I get an error:
* The server 'Server.domain.com' could not be added to the cluster. An error occurred while adding node 'Server.domain.com' to cluster 'ClusterName'.
The node failed to join the cluster because the joining node and other nodes in the cluster have incompatible operating system versions. To get more information about operating system versions of the cluster, run the Validate a Configuration Wizard or the Test-Cluster Windows PowerShell cmdlet
Googling this error looks like because the Cluster Fucntional Level is 9 and i think I can get it 8 i might be able to add it.
However the current run level is 9.
How can I downgrade the cluster functional level from 9 to 8?