Re: Where do I find the definitive man page for mdadm?
On Sat 13 Nov 2021 at 14:51:05 (+0000), Andy Smith wrote:
> On Sat, Nov 13, 2021 at 09:28:46AM -0500, Gene Heskett wrote:
> > the next question is why does
> > --scan even report it if its no good? blkid returns different UUID's.
> > Would those work?
>
> Why are you under the impression that every single thing called a
> UUID must work as a *filesystem* UUID?
>
> Lots of things have a UUID. Universally Unique IDentifiers are
> useful things. But not every UUID is a filesystem UUID. This is like
> taking the VIN from your car and putting it in fstab then asking why
> it didn't mount your car as a filesystem.
>
> MD arrays aren't filesystems, they are block devices.
>
> "blkid" does report filesystem UUIDs, according to its manpage, so
> the answer to that one is is yes.
This is, of course, the explanation for posts such as:
https://lists.debian.org/debian-user/2018/01/msg00787.html
https://lists.debian.org/debian-user/2018/01/msg00791.html
https://lists.debian.org/debian-user/2020/02/msg00155.html
Because you have to dream up (PART)LABELs yourself, it's easy
to recognise them in any context. Because UUIDs mean nothing
to humans, and are ubiquitous everywhere (tautological, I know),
you have to understand which ones have meaning in which context,
otherwise it's tempting just to throw your hands in the air
and say they keep changing.
Cheers,
David.
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