grub overwriting mbr

leemflee · 03-17-2009, 09:43 PM

Hi. I decided that I wanted to "play" with Ubuntu and install it on an external hard drive. Unfortunately, the installation process overwrote the MBR on my internal hard drive and now I cannot boot into Windows XP, which was loaded on my internal hard drive. I had Ubuntu partition the external hard drive thinking it would only install there. Does grub store the MBR anywhere before overwriting the MBR or is there a way to get my original MBR back? Thanks!!

yancek · 03-17-2009, 10:27 PM

Use your xp Installation CD, enter "R" (for recovery?) in setup, enter FIXMBR, if that doesn't work enter "FIXBOOT"

The above should restore the xp mbr on the internal. Make sure you are pointing to the correct drive.

Default for Ubuntu is to install to mbr of first drive in boot priority. Haven't installed Ubuntu recently but most distributions have an 'Advanced' tab during the bootloader installation and if you click on that, it gives an option to install to partition rather than mbr. You will then have to install Grub to the mbr of your external drive. Suggest you get partition information and post here so someone can give you command to use to do that. To get partition info, open a terminal and enter: sudo fdisk - (that's a lower case Letter L).

beachboy2 · 03-18-2009, 02:16 PM

yancek,

There is a typo in your post.
You meant to type:

sudo fdisk -l

(that's a lower case Letter L, not the number one).

tommcd · 03-18-2009, 07:54 PM

After you fix Windows MBR you can reinstall grub to the root partition of Ubuntu on external drive from the Ubuntu live CD like this:
http://users.bigpond.net.au/hermanzo...b_with_Live_CD
First, run the command "sudo fdisk -l" from the live CD to identify the Ubuntu root partition on the external drive. If you only have 1 internal drive then Ubuntu's root partition will most likely be /dev/sdb1. So set the root command in that tutorial to (hd1,0) instead of (hd0,1) as it is in that tutorial. Then the setup command will be (hd1). Then type quit.
Now set the external hard drive to be the first boot device in the computer's BIOS. You will have the option to boot Ubuntu or Windows without altering the Windows MBR.