What is UUID? UUID stand for universally unique identifier which is an identifier standard used in software construction, standardized by the Open Software Foundation (OSF) as part of the Distributed Computing Environment (DCE). UUIDs can be used to identify DVD drives, removable media (USB flashsticks) and each partition on any of your hard drives.
UUID is unique and never changes even if you switch the harddisk ordering. It is recommended to use UUID instead of traditional block name (/dev/hda1, /dev/hda5, /dev/sdb) to uniquely identify harddisk or other storage medium such as SAN, iSCSI, DAS, scsi disks volumes.