[lug] Identical UUID for MD devices?

[Rob Nagler]

On Thu, Feb 8, 2018 at 11:14 AM, Lee Woodworth wrote:
>
>
> Your mdadm --detail output shows md3 and md4 having different UUIDs and
> these are different than the raid1 uuid reported by lsblk.
>

Yes, those appear to the UUIDs of the underlying devices (look at the
lsblk). Since it is a mirror, the UUIDs are the same (guess).


>
> I have a single raid1 where I also have blkid reporting a different
> uuid for the raid1 type than the uuid from mdadm --detail.  My md device
> uses metadata format 1.2 like your md3/md4 devices but has no encryption.
>
> Is the metadata version for md0/md2 the same as md3/md4? I assume md0 and
> md2 were created some time ago. Was it a different version of mdadm?


They are all 1.2.

It seems that mdadm --stop followed by mdadm --create does not clear the
UUID, which seems like a bug to me, but what do I know. :)

As soon as I shredded enough of the disk (probably first few blocks is
enough), the raid1 UUIDs disappeared from lsblk output.

Rob
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