Seems to be related to guest agent, first of all, no?
This is partially related to the guest agent and mostly already available ( with the exception for the LUN drives See BZ#957788 ) Currently this information can be found here: https://<engine-host>/ovirt-engine/api/vms/<VMID>/disks It's available as 'logical_name' entry when the information is available. Please note that this requires the RHEVM Guest agent to be installed an running on the guests. So all that would be needed right now is the UI for it in the frontend. This feature was initially implemented for Backup solutions.
*** This bug has been marked as a duplicate of bug 968435 ***