Cannot find mount point

Hi,

I have just taken over a small network to support and cannot get my head around with one thing.

We have 2 Hyper-v servers with iSCSI storage clustered.  All Cluster Disks in Storage in Failover Cluster Manager points to a folder on the C drive (C:\ClusterStorage\Volume1 \Volume2 etc) but I just cannot find the place where those iSCSI volumes are actually mapped to those folders (In Disc manager   Change Drive Letter for iSCSI volumes is blank and there is no shortcuts to volumes in C:\ClusterStorage\Volume1 folders) so I cannot unmount them. I have figured out which volume for which folder, but still dont understand how it works.

Hope it makes sense. 

Thanks