I am not for sure where to post this, so if its in the wrong spot I am sorry.

If you are having issues with mdadm after you upgraded to ubuntu 9.04, this might help.

First off, the config file for mdadm got relocated with the distrubution upgrade. The installer does not automatically move your old config file to the new location. The old location is /etc/mdadm.conf the new location is /etc/mdadm/mdadm.conf

second, If you keep receiving a resource busy error try this (no data loss):

sudo apt-get remove mdadm

restart the computer

apt-get install mdadm

then just re assemble the raid. Example: mdadm --assemble /dev/md0 /dev/sdb1 /dev/sda1

now to make sure this continues to work after a reboot:

mdadm -Es | grep md0 >>/etc/mdadm/mdadm.conf


Hope this helps some one.

I just ran into the Ubuntu 9.04 Jaunty mdadm problem last night. I did an online upgrade from 8.10, on which I had a raid1 array for the /home filesystem. The boot would stop in the middle and drop the console into a shell, complaining about mounts with /dev/md1 and other raid filesystems. There were no raid devices at all, /dev/md1, /dev/md2 etc. There were odd files named /dev/md_d1 (as I recall from memory). I noticed that there was a new file /etc/mdadm/mdadm.conf as well as the /etc/mdadm.conf which i was familiar with. I concatenated my old /etc/mdadm.conf with the new /etc/mdadm/mdadm.conf (which comments but no entries).

cat /etc/mdadm.conf >> /etc/mdadm/mdadm.conf

Then I ^D-ed out of the maintenance shell, and the boot continued successfully.

It's very odd that they moved the location of mdadm.conf from /etc to /etc/mdadm and did not migrate the entries.