[CentOS] Re: VDQ Grub

Mon Jan 22 00:32:09 UTC 2007
Andy <aegoss at vicnet.net.au>

> Date: Sat, 20 Jan 2007 20:16:28 +0000 (UTC)
> From: Beartooth <Beartooth at swva.net>
> Subject: [CentOS] VDQ Grub

> Very Dumb Question : I have tried about four times now, using an old
> pentium2 with two hard drives (20 GB and 30 GB) to install both CentOS 4.4
> and Fedora Core 6 in such a way as to enable dual-boot between them.
> I've tried it by installing 4.4 first, and then FC6. I've tried it by
> installing FC6 first, and then 4.4. I've tried it with and without giving
> the installer permission to use both drives.
> I always end up with ability to boot only to one OS, usually the one
> installed last. Between tries I wipe both drives with DBAN.
> Surely there must be something I'm doing wrong, obvious to many but not to
> me. Clue, please?

The way it works for me is:

1) Install distro 1 on the first drive, and let it put its GRUB into the MBR 
of the drive. Mostly that is what installers want to do by default

2) Install distro 2 on the second drive but make it put its GRUB in the root 
partition of the second drive. Looking at the RHEL installation guide, this 
will be done via the "Configure advanced boot loader" option in the 
Bootloader Configuration phase

3) Once the installation of distro 2 is complete, boot into distro 1 and 
modify /boot/grub/menu.lst to include:

title Distro 2
	rootnoverify (hd1,0)
	chainloader +1

If there is any chance that you will want distro 2 to be the default at some 
stage, put this before distro 1, which will look like:

title Fedora Core (2.6.14-1.1656_FC4)
	root (hd0,0)
	kernel /vmlinuz-2.6.14-1.1656_FC4 ro root=/dev/VolGroup00/LogVol00 rhgb quiet
	initrd /initrd-2.6.14-1.1656_FC4.img

and modify the 

default= 0

to 1

Then if you later want distro 2 to be default you can change it back to 0 
again. Doing it this way round avoids confusion if distro 1 gets a kernel 
upgrade and a new title line is added.

I can recommend the following for GRUB wisdom:

* http://www.linuxquestions.org/linux/blog/saikee
* A grub menu booting 100+ systems of Dos, Windows, Linux, BSD and Solaris: 
* Just booting tips: http://www.justlinux.com/forum/showthread.php?t=144294
* Saikee's grub booting tips: 

Andy Goss