I accidentally overwrote all my RAID1 superblocks with garbage. I think this happened because I ALT-CTRL-DEL booted when the Ubuntu had put me in some kind of hard disk recovery mode. My display wasn't working and I did this "blind".
Looking at my RAID partitions, I see this:
# mdadm --examine /dev/sdc2 /dev/sdc2: Magic : a92b4efc Version : 0.90.00 UUID : 00000000:00000000:00000000:00000000 Creation Time : Fri Nov 1 18:59:05 2013 Raid Level : -unknown- Raid Devices : 0 Total Devices : 1 Preferred Minor : 127 Update Time : Fri Nov 1 18:59:05 2013 State : active Active Devices : 0 Working Devices : 1 Failed Devices : 0 Spare Devices : 1 Checksum : 6b1f0d22 - correct Events : 1 Number Major Minor RaidDevice State this 0 8 34 0 spare /dev/sdc2 0 0 8 34 0 spare /dev/sdc2
It is apparent that the superblocks have been fully overwritten by garbage. Both disks (sdb2, sdc2) look the same, the information is garbage, uuid is all zeros, raid level: unknown, raid devices: 0, etc.
The best bet I have is this:
mdadm --create --assume-clean --metadata=0.90 /dev/md0 --level=1 --raid-devices=2 /dev/sdb2 /dev/sdc2
Can I re-create my RAID array using mdadm --create like this?
On the RAID stack, I have an LVM2 physical volume. Can I somehow access my LVM2 data from the individual disks or backup disk images?
GRUB is able to find my initrd and kernel image from the disks, /boot is on ext4 root partition filesystem on top of LVM2, it is not a separate partition. So I believe the data is mostly intact, and the superblocks are gone.
edit: add --assume-clean to mdadm command line