filesystem-uuid · shipping · also file system UUID, filesystem universally unique identifier

Filesystem UUID

A filesystem UUID is an identifier stored in filesystem metadata and used to select that filesystem independently of its device pathname.

Related Observatory article: Filesystem UUID on hesela.com

Ext4 stores its 128-bit s_uuid at byte offset 0x68 within the superblock; this is distinct from a containing partition's identifier. [1]

Linux mount's UUID= and PARTUUID= selectors refer to different layers. Reformatting a filesystem does not itself change the partition identifier. Copied filesystems can retain the same UUID. [2]

A filesystem UUID is an identifier, not a content digest. Matching UUIDs do not establish that two recovery artifacts are distinct or unchanged.

Relations

related

Unique partition GUID, Partition type GUID, Ext4

Limitations

• UUID availability and representation depend on the filesystem format.
• A recognized identifier does not establish filesystem health or recovery completeness.

Citations

1. Linux v6.12 ext4 superblock: s_uuid field (accessed 2026-11-03)
2. util-linux v2.41 mount(8): filesystem and partition selectors (accessed 2026-11-03)

JSON: /data/terms/filesystem-uuid.json