On Tue, Nov 26, 2024 at 09:57:59AM +0100, Roger Price wrote: > On Tue, 26 Nov 2024, Felix Miata wrote: > > > Members of a raid filesystem have to be seen as an integral part of one > > filesystem, > > a special case. It's another reason I stick to use of LABELs. > > > > # lsblk -f | egrep -A1 'raid|NAME' > > NAME FSTYPE FSVER LABEL UUID FSAVAIL FSUSE% > > MOUNTPOINTS > > -- > > ├─sda5 linux_raid_member 1.0 msi85:0tmp 6cb3… > > │ └─md0 ext4 1.0 hr18md0tmp 8aea… > > -- > > ├─sdb5 linux_raid_member 1.0 msi85:0tmp 6cb3… > > │ └─md0 ext4 1.0 hr18md0tmp 8aea… > > It makes sense to me that md0 should be reported twice with the same UUID, > but surely the underlying hardware should be getting a unique UUID?
The UUID is in a slot of the /file system/. The "hardware" (what do you mean by that?) most probably doesn't know what an UUID is. > The use of LABELs is attractive, but I notice you have the same label for > sda5 and sdb5. This means you cannot intervene on "msi85:0tmp". You have > to specify sda5 or sdb5. LABELS exist at two levels: partitions (if your partition table allows for it) and file systems. All things which are "in" the file system will be "in" the RAID, because you make the file system "on top" of the RAID device. Of course, if the RAID system allows to attach individual "things" (perhaps UUIDs?) to each of its components you could do that (no idea whether Linux RAID allows that, though). But the file system UUIDs and LABELs are "above" this. You can't differentiate RAID components by this. It's as if you ask for the plate number of your rear left tyre. The whole car has one. Keep the layers apart. It gets confusing quickly. Cheers -- t
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