Hi there
I have spent the better part of a day last week solving the same issue.
I had upgraded one of my production server from 9.10 to 10.04 w/o knowing that it was due to fail...
Anyway, here is my post (in french) on the subject:
http://forum.ovh.com/showthread.php?p=371059#post371059
For the non french readers...:
For those who have upgraded from 9.10 to 10.04 using the OVH kernel (and thus, who are stuck at boot), and if you use software RAID... here's what I ended up doing to get the server back on it's feets:
- boot in rescue mode and mount the root of your system
root@rescue:~# mount /dev/md1 /mnt
root@rescue:~# mount --bind /dev /mnt/dev
root@rescue:~# mount --bind /proc /mnt/proc
root@rescue:~# chroot /mnt
- install grub2 and the linux stock image (don't worry about some grep errors... the OVH kernel has been built without modules)
root@rescue:~# apt-get install grub2 linux-image
- manually declare the needed kernel modules (I had to add r8169: this is the network card on the OVH servers I use -- w/o it, the system would boot but couldn't reach the network)
root@rescue:~# vi /etc/modules
loop
rtc
raid
mdraid
ext2
r8169
root@rescue:~# update-initramfs -c -k all
- I also had to explicitly declare the raid devices in the raid configuration (wouldn't get auto-detected by the kernel)
root@rescue:~# mdadm --detail --scan --verbose >> /etc/mdadm/mdadm.conf
root@rescue:~# vi /etc/mdadm/mdadm.conf
(replace metadata=00.90 by metadata=0.90)
root@rescue:~# update-initramfs -c -k all
- make sure that grub is properly installed on both hard drives
root@rescue:~# update-grub2
root@rescue:~# grub-install /dev/sda
root@rescue:~# grub-install /dev/sdb
- reboot and hope for the best
The same procedure can also be used before upgrade (install a Ubuntu 9.10 stock kernel before upgrade; you will also need to declare the modules & raid configuration before rebooting on it). I have successfully tested it: if you can boot your 9.10 system with the stock Ubuntu kernel, the upgrade to 10.04 is painless (at least, on my system).
Cheers