LVM2 Labels And UUID-s

• In order to identify that a physical device is managed by LVM, an LVM2 label is written on one of its first 4 sectors.
• This label is used, during LVM scans, to find its devices.
• In order to identify physical volumes belonging to volume groups, a UUID is assigned to each of them, and stored on them.
• The UUID of a physical device is stored as part of the volume-group meta-data area on the device: at the start (beginning with 5th sector), at the end, or on both sides (for redundancy).
• By default, the UUID is generated randomally.
• We can force a specific UUID when marking a physical volume, in case we are intending to load an LVM setup from backup.

Originally written by guy keren