Hi, On Tue, Nov 26, 2024 at 09:11:58AM +0100, Roger Price wrote: > On Tue, 26 Nov 2024, George at Clug wrote: > > > "$ lsblk -f" output is very nice ! Thanks. > > I tried this and noticed UUID duplication in the output. I attach a small > text file which shows what I saw. UUID sdg6 = UUID sdh6 ! > > NAME FSTYPE UUID > ... > ├─sdg6 linux_raid_membe3 f5e37a29-357a-e3f2-c731-e29eddce5e > │ └─md3 ext4 1.039c24711-ab43-497c-bf3e-12b4032575a.4G > ... > ├─sdh6 linux_raid_membe3 f5e37a29-357a-e3f2-c731-e29eddce5e91 > │ └─md3 ext4 39c39c24711-ab43-497c-bf3e-12b403257.4G > > If I wanted to retire /dev/sdg6 from the Raid array, I would not be able to > use the UUID, only the unique SDxn. > > Aren't UUIDs supposed to be unique?
People see the phrase "UUID" and think every UUID is the same. Your computer has lots of different UUIDs. What you see above is the mdadm array UUID. It is meant to be unique PER ARRAY (on that system). Those devices are part of the same array thus they have the same ARRAY UUID. You don't have a filesystem on /dev/sdg6 or /dev/sdh6. If you did then it would have a FILESYSTEM UUID. If you want to refer to sdg6 or sdh6 without using /dev/sd* then you can use any of the /dev/disk/by-* paths for them. See also the output of "mdadm --examine /dev/sdg6" and "mdadm --detail /dev/md3". Thanks, Andy -- https://bitfolk.com/ -- No-nonsense VPS hosting
