28.2. UUID and Other Persistent Identifiers

If a storage device contains a file system, then that file system may provide one or both of the following:
  • Universally Unique Identifier (UUID)
  • File system label
These identifiers are persistent, and based on metadata written on the device by certain applications. They may also be used to access the device using the symlinks maintained by the operating system in the /dev/disk/by-label/ (e.g. boot -> ../../sda1) and /dev/disk/by-uuid/ (e.g. f8bf09e3-4c16-4d91-bd5e-6f62da165c08 -> ../../sda1) directories.
md and LVM write metadata on the storage device, and read that data when they scan devices. In each case, the metadata contains a UUID, so that the device can be identified regardless of the path (or system) used to access it. As a result, the device names presented by these facilities are persistent, as long as the metadata remains unchanged.