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Old 05-15-2009, 08:21 PM   #1
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Grub Error 21 Dual Boot.

Hello, ive looked all over online and haven't been able to find anything to help as of yet so i figured id ask you guys. The other night I installed Ubuntu 9.04 to my external hard drive through my Windows Xp Computer. Now when i disconnect my external drive and go to load Windows it just goes to grub right away and wont load since my external is not connected. I know some people said some things about putting in a windows install disk and doing something with chkdsk/fixmbr but i dont have my windows disk. Any help would be greatly appreciated. Also, really really new to linux so more detailed instructions would be a great help as well. Thanks.
Old 05-15-2009, 10:34 PM   #2
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The default installation for Ubuntu will install Grub stage1 file to the master boot record of the disk which is first in boot priority which in your case would be the internal drive with xp on it. There are a number of files which constitute the Grub bootloader and only stage1 is in the mbr, the rest of the files are in the /boot/grub/ directory - on your external drive. That would be why you can't boot with the external disconnected.

Can you boot Ubuntu? If not, use the install CD and open a terminal and run command: sudo fdisk -l (lower case letter L) and post output here. Also, what are your intentions with the external? Methods for booting will vary if you plan to keep the external always or regularly connected or if you will only occasionally have it connected. You can repair the xp mbr with your installataion CD. If you don't have one, you can download SuperGrubDisk or a boot disk from You should be able to find how to repair xp mbr with a quick search here at LQ. If you have problems understanding steps, post again.


boot, dual, error, external, grub, ubuntu, windows, xp

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