[lug] Identical UUID for MD devices?

[Lee Woodworth]

On 02/08/2018 09:25 AM, Rob Nagler wrote:
 > I created two RAID1 devices with mdadm, but the UUIDs are identical (see
 > below). I actually created and destroyed an array with all four disks,
 > wiped the signatures, and then recreated the arrays as separate mirrored
 > disks. I'm going to recreate the arrays, but I was wondering if someone had
 > seen this before. Thanks, Rob
 > ....

Your mdadm --detail output shows md3 and md4 having different UUIDs and
these are different than the raid1 uuid reported by lsblk.

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?

sw versions:
   mdadm 3.4
   util-linux 2.30.2
   kernel 4.14.12