Basic working system details:
I used the Ubuntu 12.04 server CD to install a server.
I have 2 disks. I made a raid 1 array just like in ubuntu server guide : https://help.ubuntu.com/12.04/serverguide/advanced-installation.html
So I have 2 MD devices - one for swap - 4 GB, one for / - remaining 496 GB.
Everything worked just fine for last 2 months.
But now I get message:
error: Unsupported RAID level: -1000000
No such disk
I tried to use rescue mode from server CD, used graphical interface to assemble raid array (partitions seem to be fine).
I tried mdadm -D /dev/md0 and mdadm -D /dev/md1 And got "md device does not appear to be active".
Any advice what to do next?
Update: I tried to follow http://superuser.com/questions/117824/how-to-get-an-inactive-raid-device-working-again But I can't use a resolution in that post, because I assembled raid array with a help of repair CD and even after that raid array is inactive and I need to boot up in the first place to add output of mdadm --examine --scan to /etc/mdadm/mdadm.conf (which is the resolution in that post)
Update2: I managed to assemble and now able to choose Ubuntu recovery mode, but during boot I get this message:
Failed to spawn friendly-recovery post-stop process: unable to execute: No such file or directory
Update3: We found some data loss and stuck again :) Then decided to ask question here, now about data loss: http://askubuntu.com/questions/174172/data-hidden-or-lost-on-hdds-in-raid1-on-ubuntu-server-12-04#174172