When you try to add a Storage Spaces Direct (S2D) or Scale-Out File Server (SOFS) cluster to the storage fabric in a Microsoft System Center 2016 Virtual Machine Manager (VMM) cluster, you receive the following error message:
Registration of the storage subsystem <CLUSTER> for user <ACCOUNT> failed from <VMM NODE> with error code 1 [SM_RC_NOT_SUPPORTED].
Specify a valid subsystem name, and user credentials for registering the subsystem.
This issue occurs if the VMM cluster was upgraded from an earlier version of Windows to Window Server 2016, and if it's running at a lower functional level than the storage cluster.
To fix the issue, follow these steps on the VMM cluster:
Check that all cluster nodes are in the Up state by running the following Windows PowerShell cmdlet:
Update the cluster functional level by running the following PowerShell cmdlet:
Note Even if both the VMM cluster and storage cluster are running at the Windows Server 2016 functional level (functional level 9), you may have to run this cmdlet on the clustered VMM server to fix the issue.