Today I was testing an upgrade from Windows Server 2012 to Windows Server 2012 R2, for our Windows File Servers.

I tested two WS2012 File Servers, with iSCSI disks in a Failover Cluster. I upgraded each node in the cluster individually and had to take the node out of the cluster. After the upgrade I found that I couldn’t add the node to the Failover Cluster anymore.

At this point I decided to create the cluster again, and destroyed the ‘old’ cluster via the Failover Cluster Manager. I hoped (my mistake), that the connected disks would be released again. For one of the three disks, this was the case. I created the cluster again, but couldn’t add the iSCSI disks.

Every time I tried to look for disks, the message: “No disks suitable for cluster disks were found.”, appeared.

I checked the connection, disconnected and connected the disks again via iSCSI Initiator, tried diskpart and other logical tools and commands. The disks kept being in a RAW state.

I tried to format and delete the volume, but the error: ”The requested resource is in use.”, kept appearing.

The disk could be found, but apparently it was still assigned or in use by the previous cluster.

After some digging I found the PowerShell command:
Clear-ClusterDiskReservation –Disk
Source: http://technet.microsoft.com/en-us/library/ee461016.aspx

I looked up the disk number in disk management (in my case number 4), opened PowerShell as an admin and ran the following command:
“Clear-ClusterDiskReservation –Disk 4”

This seemed to be the solution and I could add the disk again.

I recommend running chkdsk on the disk afterwards.