When trying to boot a target device, we observe-
When a target device boots up with the assigned vdisk, a lock gets created on that vdisk. The locked vDisk icon appears with a small lock on it.
Under certain circumstances the locks are not released properly. In cases where a target device tries and fails to boot with a specific vdisk, the locks do not get released properly. If the same target device boots again, the same lock is used and no problem occurs.