I was rebuilding RAID on my production server and due to some unexpected reason sever got rebooted automatically before I could complete grub configuration, MBR got corrupted , was getting error 15 on grub prompt. I had been breaking my head from two hours , then found a link which helped me to recover from this situation.
I just want to share How can you easily recover from this
Step 1:- Reboot your server in rescue mode.
Step 2:- Mount your root partition to /mnt ,In my case / was mounted on /dev/md1.(I am using RAID1)
mount /dev/md1 /mnt
Step 3:- mount proc ,usr, and dev partiton to /mnt , Grub error 15 comes due to missing dev directory , it is important to mount this also.
mount -t proc none /mnt/proc
mount –rbind /dev /mnt/dev
mount /dev/mapper/vg00-usr /usr
Step 4 :- chroot to mnt directory
chroot /mnt /bin/bash
Step 5 :- source /etc/profile
Step 6 :- cd /boot/grub
At this stage you can reboot your server but better to follow the below steps of grub configuration :-
grub> device (hd0) /dev/sda
grub> root (hd0,0)
grub> setup (hd0)
grub> device (hd1) /dev/sdb
grub> root (hd1,0)
grub> setup (hd1)
I hope this helps you