When <disk><reservations> is specified, a check should be performed that no other domain on this host is using the same shared LUN.

This is important because a VM that does not hold the reservation but is running on the same host of a VM that holds the reservation can still write to the shared LUN even if the other VM has exclusive access for example, as the storage will deny access to the node and not the the VM.

Note: this does not apply to NPIV setups.