If you have an issue booting your xen 5 because you have loose MBR information, here is how you can restore it very quickly.
Proceed booting your server with a live cd distribution, like wifiSlax, and run the next commands.
mount the necessary partitions in your harddisk to have / and /boot mounted.
Let’s say you have sda1 assigned to boot and sda2 to root partition.
# mount /dev/sda2 /mnt # mount /dev/sda1 /mnt/boot
or like in my case, mount your RAID1 partitions to access to yor root filesystem.
check you have mdad devices, and check its status to mount it.
# cat /proc/mdstat # mount /dev/md0 /mnt
Tip*: remember, you mdadm partitions are being read when the live cd boots. WifiSlax does. If your boot cd doesn’t, try other, it might do it.
and now we must assure acess to dev, proc and sys partitions.
# mount --bind /proc /mnt/proc # mount --bind /sys /mnt/sys # mount --bind /dev /mnt/dev
run chroot to jail your system and run the commands from the Xen itself.
# chroot /tmp/ahora /bin/bash
Now, check /boot configuration files for extlinux and run the next command to restore your MBR information with…
# extlinux -i /boot