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?

Solution

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