Re: The "uniqueness" of UUIDs
On Tue, Nov 26, 2024 at 04:35:13PM +0100, Roger Price wrote:
My understanding is that a Linux file system is a hierachical
structure starting with the root directory (/) which organises the
directories and files. The files are stored on various devices which
have identities such as /dev/sdxn, UUID or LABEL. These identities
are for the devices, not parts of the file system.
Your understanding is wrong: the UUIDs you are talking about are a
feature of the filesystem--that's why they appear in lsblk -f
(filesystem) output. You can find the same UUID in filesystem-specific
tools such as dumpe2fs; lsblk has logic to extract a UUID from each
filesystem that it knows how to parse and which contains a UUID. There
are other UUIDs associated with some storage devices, partitions, and
all sorts of other things on a modern system, but they are not the
filesystem UUID and are not what is displayed in lsblk -f. (lsblk -f
does include some UUIDs which aren't in filesystems, but which are in
some other on-disk structure logically similar to a filesystem; an
example is LVM physical volumes [also visible via pvs -v].)
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