Share your knowledge at the LQ Wiki.
Go Back > Forums > Linux Forums > Linux - Newbie
User Name
Linux - Newbie This Linux forum is for members that are new to Linux.
Just starting out and have a question? If it is not in the man pages or the how-to's this is the place!


  Search this Thread
Old 11-26-2008, 02:05 PM   #1
LQ Newbie
Registered: Nov 2008
Posts: 4

Rep: Reputation: 0
Re-installing Linux on a dual-boot system: what happens with Grub and the MBR?

OK, so I've got my dual-boot system up and running with Win XP and Fedora. Grub was installed on the MBR and everything is fine.
I was just wondering - if I decide to switch distro's or reinstall Fedora for some reason, what happens with the MBR? Can I just delete the Linux partitions using Partition Manager (via Windows) and then re-install? But doesn't that mean Grub gets installed on the MBR a second time, making a mess?

Please advise.
Old 11-26-2008, 02:21 PM   #2
Registered: Jun 2007
Location: San Francisco
Distribution: Centos 4, Debian
Posts: 55

Rep: Reputation: 16
Are you adding a new distro or replacing Fedora? If you're replacing it, just go through the install process as usual and it should overwrite your Linux partitions just fine.
Old 11-26-2008, 02:22 PM   #3
LQ Guru
Registered: Feb 2003
Location: Blue Ridge Mountain
Distribution: Linux Mint 17, Debian 8
Posts: 7,865

Rep: Reputation: 311Reputation: 311Reputation: 311Reputation: 311
Grub is installed in two places, the MBR and in /boot/grub/menu.lst. The portion of Grub on the MBR points to /boot/grub/menu.lst.

You can have several Linux distributions installed in different partitions, each with its own copy of /boot/grub/menu.lst, but the MBR can only point to one of the menu.lst files.

If you delete the partition which contains the menu.lst that your MBR points to then booting the computer will fail when Grub cannot find the menu.lst file.

So when you reinstall or install a distribution to a new partition you have to plan ahead as to what you want the installer to do about the MBR. You can tell the installer to not install Grub to the MBR or you can tell the installer to create its own version of menu.lst and point the MBR at the new menu.lst.

Steve Stites
Old 11-26-2008, 02:24 PM   #4
Senior Member
Registered: Dec 2007
Location: In front of my LINUX OR MAC BOX
Distribution: Mandriva 2009 X86_64 suse 11.3 X86_64 Centos X86_64 Debian X86_64 Linux MInt 86_64 OS X
Posts: 2,369

Rep: Reputation: Disabled
Just imagine you wish to reinstall Fedora and let use here old space and install GRUB in MBR again than the old GRUB will overwritten by new one.
Same happens if you replace Fedora by for instance opensuse and let opensuse use the Fedora space and GRUB in MBR
than the GRUB will be overwritten by Opensuse GRUB
Old 11-26-2008, 02:25 PM   #5
LQ Veteran
Registered: Nov 2005
Location: Annapolis, MD
Distribution: Arch/XFCE
Posts: 17,802

Rep: Reputation: 738Reputation: 738Reputation: 738Reputation: 738Reputation: 738Reputation: 738Reputation: 738
Welcome to LQ!!

Most Linux installers give you the option of NOT installing a bootloader (or at least the option to put it on a floppy, USB stick, etc.)

Most Linux installers ALSO are quite good at detecting the other OSes present and configuring GRUB accordingly.

But doesn't that mean Grub gets installed on the MBR a second time, making a mess?
It doesn't "make a mess"---all that happens is that, when you install GRUB to the MBR, you overwrite whatever was there before.

I currently take the lazy way out--I let each installer take the MBR. Then, if it did not correctly set up for all my other installation, I just go in and fix it by hand.
Old 11-26-2008, 02:47 PM   #6
LQ Newbie
Registered: Nov 2008
Posts: 4

Original Poster
Rep: Reputation: 0
Got it, thanks everybody for clearing that up


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Dual-booting: GRUB on the /boot partition instead of the MBR doesn't work for me jem Linux - Newbie 3 11-26-2008 09:38 AM
dual boot (RHEL3 and RHEL4) problem: need guidance to edit grub.conf in MBR lgpage Linux - Software 1 02-16-2007 12:05 PM
dual boot mbr grub problems Xris718 Linux - General 4 08-09-2006 06:52 PM
mbr issue on dual boot rhl7.1 dominant system m3rajk Linux - Software 8 12-04-2003 06:17 PM
GRUB for LINUX to boot dual system kpilaiku Linux - General 2 04-11-2003 03:46 PM > Forums > Linux Forums > Linux - Newbie

All times are GMT -5. The time now is 09:52 AM.

Main Menu
Write for LQ is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration