What scenarios causes a hard drive UUID to change?

Question

What scenarios causes a hard drive UUID to change? Are there any manufacturer assigned unique ids for hard drives that is less likely to change?

Answer 1

The Universally Unique Identifier (UUID) is integrated in the filesystem. By this we can recognize a filesystem by it's unique number to avoid confusion (e.g. when mounting drives).

Anything that affects the file-system will also change its UUID. Under normal circumstances this will be

• formatting a drive
• (re-)partitioning of a drive

Under rare circumstances we may be faced with an external drive that mounts a temporary filesystem (e.g. live systems booting from an USB drive). In this case the UUID may also change.

We can manually assign a fixed UUID to a drive if we wish:

• How do I change UUID of a disk to whatever I want?

^{This would be another scenario where the UUID of a drive changes.}

In case we need manual control over the disk identifiers we may also use a disk LABEL:

• Constant UUID on USB install