[SOLVED] Upgrade of L:inux loses reference to RAID array

mfoley · 01-21-2024, 07:45 PM

I've just upgraded a computer to Slackware 15.0. This computer has two RAID arrays (3 including a swap array):

Code:

/dev/md2         swap             swap        defaults         0   0
/dev/md1         /                ext4        defaults         1   1
/dev/md0        /mnt/RAID       auto    defaults,acl    0       0

MD1 is the boot device. MD0 is the NAS and was unmounted and removed from /etc/fstab during the upgrade. After upgrading, the computer booted just fine off MD1.

Then I tried to mount /dev/md0 and got "can't read superblock on /dev/md0". When I did a blkid on this system, /dev/md0 was nowhere listed, but I now have a /dev/md127! When I mounted that (ro) it does have the contents of what used to be /dev/md0. I don't know if this had anything to do with the OS upgrade, but it was definitely /dev/md0 before.

How can I "rename" this array back to /dev/md0?

michaelk · 01-21-2024, 08:51 PM

Look at the output of the command:

Quote:

mdadm --detail /dev/md127

At the bottom there will be a line

Quote:

Name : hostname:XX (local to host hostname)

Is XX 0 or 127?

Code:

mdadm --stop /dev/md127
mdadm --assemble /dev/md/0 --name=0 --update=name /dev/sdx /dev/sdy ...

Update your /etc/mdadm.conf file if necessary.

That should work but as always make sure important data is backed up...

mfoley · 01-21-2024, 09:11 PM

Quote:

Originally Posted by michaelk

Look at the output of the command:

At the bottom there will be a line

Code:

Name : hostname:XX (local to host hostname)

Is XX 0 or 127?

Before trying your other suggestions I thought I'd answer this question first:

Code:

Name : OHPRSstorage:0

Furthermore, I followed your suggestion to check mdadm.conf. As it turned out, the Slackware upgrade clobbered that file and saved the original in mdadm.conf.orig. I renamed that back to mdadm.conf, rebooted and all is back to normal!!!

I'm usually very carefully check the .new configs before keeping or overwriting, but I must have missed that one.

Thanks for putting me on the right track!