Restoring Grub Boot Loader

masterio

Nov 15 2006, 10:55 AM

Hi guys,

Few days ago my friend ask me to reinstall Windows on his computer. The problem is he has dual OS, ubuntu linux(Dapper Drake) and Windows XP. If I reinstall the Windows the Grub loader on MBR will overwritten by Windows XP. i know after reinstalling Windows we cannot boot to Ubuntu.

I'm newbie, So my question is, How we restore the Grub Loader back? I've try to boot from ubuntu using Live CD mode. But I still confuse

the step-by-step how to restore the grub.

Please help

Thanks!

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yordan

Nov 15 2006, 11:30 AM

I'm not familiar with Ubuntu. I do this kind of things with Mandrake of Mandriva.
It should be the same kind of problem and the same solution on all distros, just try my way, it's not harmful as long as you do not clik "format the hard disk".
With Mandrake or Mandriva, and probably with Ubuntu, you boot on the first install CD (or on the install DVD), choose "install or update", then choose "update", it verifies a lot of things and you see "installing the bootloader". Choose to put the boot loader on your first disk, and everything should go fine.
Hope this helped.
Yordan

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qwijibow

Nov 15 2006, 01:55 PM

You Have Two Options............

1) The Usual Way....
After Installing WindowsXP, Boot a Linux Rescue Disk and Re-Install Grub with the command. "grub-install"

read man grub for more info.

typically....

CODE

mount /dev/your_boot_partiton /boot
grub-install --root-directory /boot /dev/hda

2) The Easy, 733T haX0r Linux GuRu Way....

The Boot Sector is Stored on the first 512 Bytes of the physical Disk.

so... Backup your boot sector to a file like so...

CODE

dd if=/dev/hda of=/BootSectorBackup.bin bs=512 count=1

Copy the backup file to a floppy disk / whatever.

Install Windows XP.

Boot a Linux Rescue Disk.

then Copy your Origonal Boot Sector Over whatever Garbage WindowsXP put there with the command

CODE

dd if=/BootSectorBackup.bin of=/dev/hda bs=512 count=1

If at all in Doubt... Use Method 1..
If you Make a Mistake With Method 2, you can waye boodbye to your Partiton Table... File System, and look forward to a full re-partiton and re-format.

Good Luck.

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masterio

Nov 15 2006, 03:27 PM

Hi qwijibow,

I have tried the first method but it seems the parameter is wrong because when I run

$ grub-install --root-directory /boot /dev/hda

the grub-install just return same as we only typed $ grub-install. When run the grub shell, I saw a few command (I think) that can be used to fix grub. Like "setup" or "install",

CODE

grub> help setup
setup: setup [--prefix=DIR] [--stage2=STAGE2_FILE] [--force-lba] INSTALL_DEVICE
[IMAGE_DEVICE]
    Set up the installation of GRUB automatically. This command uses
    the more flexible command "install" in the backend and installs
    GRUB into the device INSTALL_DEVICE. If IMAGE_DEVICE is
    specified, then find the GRUB images in the device IMAGE_DEVICE,
    otherwise use the current "root device", which can be set by the
    command "root". If you know that your BIOS should support LBA but
    GRUB doesn't work in LBA mode, specify the option `--force-lba'.
    If you install GRUB under the grub shell and you cannot unmount
    the partition where GRUB images reside, specify the option
    `--stage2' to tell GRUB the file name under your OS.

grub>

I'm still confuse about INSTALL_DEVICE.

CODE

grub> setup --prefix=/boot/grub --stage2=/boot/grub/stage2 (hd0,0)

Error 12: Invalid device requested

OR

grub> setup --prefix=/boot/grub --stage2=/boot/grub/stage2 /dev/hda

Error 11: Unrecognized device string

For method 2, I'll not do it because it's to danger and can make my partition table corrupt!. So, there is another way?

Thanks

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xboxrulz

Nov 16 2006, 02:02 AM

GRUB handles each partition as a number... so if I want to install it into the the MBR, usually it would be:

grub-install hd(0,0)

xboxrulz

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ignite

Nov 17 2006, 09:18 AM

QUOTE(masterio @ Nov 15 2006, 12:55 PM)

the step-by-step how to restore the grub.

Please help
Thanks!

If you can boot from CD, simplest method is to mount linux partitions, then chroot to it, then run grub-install.
TIP: fdisk -l will display all partitions at all drives.

In general, for any distro, even you havn't live CD, restoring can be done in such steps:
1) Find any working linux sustem
2) Create GRUB boot floppy:
# cd /usr/share/grub/i386-pc
# dd if=stage1 of=/dev/fd0 bs=512 count=1
1+0 records in
1+0 records out
# dd if=stage2 of=/dev/fd0 bs=512 seek=1
153+1 records in
153+1 records out
3) Boot from that floppy, then (quote from GRUB info page):

Once started, GRUB will show the command-line interface (*note
Command-line interface:

. First, set the GRUB's "root device"(1)
(*note Installing GRUB natively-Footnote-1:

to the partition
containing the boot directory, like this:

grub> root (hd0,0)

If you are not sure which partition actually holds this directory,
use the command `find' (*note find:

, like this:

grub> find /boot/grub/stage1

This will search for the file name `/boot/grub/stage1' and show the
devices which contain the file.

Once you've set the root device correctly, run the command `setup'
(*note setup:

:

grub> setup (hd0)

For more information type info grub

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abhay

Feb 27 2007, 05:08 AM

QUOTE(ignite @ Nov 17 2006, 02:48 PM)

. First, set the GRUB's "root device"(1)
(*note Installing GRUB natively-Footnote-1:

to the partition
containing the boot directory, like this:

grub> root (hd0,0)

If you are not sure which partition actually holds this directory,
use the command `find' (*note find:

:

grub> setup (hd0)
For more information type info grub

The RHEL installer provides the GRUB boot loader, GRUB (the GRand Unified Boot-loader).

/boot/grub/grub/grub.conf has a format of global options followed by boot stanzas. Here is a sample grub.conf:

timeout=5
splashimage=(hd0,0) /grub/splash.xpm.gz
password --md5 $1$/iX9y$Bkskfdsd4443gnff
default=0
title Red Hat Enterprise Linux AS (2.6.9-648_EL)
root(hd0,1)
kernel /vmlinuz-2.6.9.EL ro root=/dev/VolGroup00/LogVol00

initrd /initrd-2.6.9-648.EL.img
title Windows XP Pro
rootnoverify (hd0,0)
chainloader +1

IF ggrub-install fails for some reason try the following:

1. type the command grub and press enter

2. type root (hd0,0)

3. type setup (hd0)

4. type quit

IF still problem occures, then reinstall the grub by

/sbin/grub-install /dev/hda or use these three commands:

Have a nice day

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Vlastik

Mar 10 2007, 10:43 AM

QUOTE(abhay @ Feb 27 2007, 06:08 AM)

1. type the command grub and press enter

2. type root (hd0,0)

3. type setup (hd0)

4. type quit

root(hd0,0) means partition where kernel is stored w.m. where /boot/ directory is stored
hd0 = first IDE disk, 0 means first partition on this disk - you can use tab key to show alternatives

setup(hd0) means where to install grub to MBR, on which disk - so in this case in the MBR on the first IDE disk

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FeedBacker

Mar 4 2008, 04:02 PM

Restoring Red Hat Enterprise Linux Boot Loader
Restoring Grub Boot Loader

Hi

I had dual boot system of windows xp and RHEL 3.0.After some days I have reinstalled XP.But now I want to get back RHEL 3.0 again.

How Can I restore Grub boot loader again?if I can restore the grub boot loader again,will it give me the option of selecting the operating system?

Please help me out...

-question by ruhul

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FeedBacker

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Hi,
I installed solaris 10 first.Then I install windows xp in another partition.When I boot my system,there is no options for os choices.It directly goes to the windows xp ,how to get os choices menu.

Thanks in Advance.

By,
Ruban demel.

-reply by Ruban

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iGuest

Sep 18 2009, 11:14 AM

It seems I
Restoring Grub Boot Loader

Ok ,heres the long and short of it:

I have this stupid anal obession of cleaning up things. I managed to make my windows xp go away from my boot loader. I have Mandriva 2009 spring editon. Of course loaded on the first past of my primary drive. I have a second drive on a seperate IDE. It of course is Windows XP. So lately I have been going in to BIOS and just flipping the drives and it works fine. But I really want my windows back on the boot loader line of.

dev/sdb1 isn't working I tried that on the add feature on the second page of the boot loader in the boot loaders "menu" for lack of better word and then tried loading it as a "other os windos os" of course. I tried all the ones there and it still wouldn't boot. I tried it in root too but I think I need more info for milling around in there.

I actually didn't blow out the linux, liunx safe boot or windows. I blew out the two files that came up after a few time booting up linux i586 , I removed them from the loaders menu. Then added "clean /tmp at boot" checked on the loaders advanced section on the first page of the menu.

I don't think I hurt or damaged any files in doing what I've done. Could someone help me figure this out? I just want my Boot laoder to recognized Windows and boot it according to my key stroke at time of boot.

-question by an_ok_joe

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iGuest

May 1 2009, 04:31 PM

dual booting: Fixing Grub Boot Loader after installing windows
Restoring Grub Boot Loader

If you already have linux installed and you install windows afterwards, I found this was the cleanest and easiest way to fix my grub boot loader if I had to reinstall windows and my boot loader disappeared.

TO FIX THE GRUB BOOT LOADER:
1. Load a live CD
2. Find where the linux partition is installed (/dev/sda4)
$ fdisk -l
3. Make a directory to mount the real root partition on
$ sudo mkdir realroot
4. Mount the linux partition in the real root folder so you can access the boot loader
$ sudo mount /dev/sda4 realroot
5. Use grub-install to redirect the real boot loader to the windows boot partition (the first part of the disk sector)
$ grub-install --root-directory=realroot /dev/sda

-reply by KnogleMopwater

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