When changing the drive letter or mount point for an SFW Dynamic Volume that is part of a VMDg resource in MSCS, the change has to be made on all nodes in the cluster due to the way volumes are managed via Microsoft Mount Manager (MM). The MM is responsible for managing volume names. For each volume, it stores a name that is unique and is permanently identified with the volume, even after the volume has been removed the from system. The MM also manages less permanent names, like drive letters and mount points, that persist across reboots, but whose assignments can change as volumes are added to or removed from the system.

Because the MM manages volumes that are specific to an individual node, changing the drive letter or mount point on one node does not update the MM on any other nodes. To change a drive letter or mount point for a volume in an MSCS cluster, the cluster group that contains the VMDg resource will need to be moved to each node in the cluster with the drive letter or mount point change made on each node.

For more information about the Microsoft Mount Manager, please refer to Microsoft's knowledge base.