Cannot find mounting point in hyper-v 2008

Hi,
I have just taken over a small network to support and cannot get my head around with one thing.
We have 2 windows 2008 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.
Thanks