[CentOS] Re: VDQ Grub

Mon Jan 22 11:59:09 UTC 2007
Johnny Hughes <mailing-lists at hughesjr.com>

On Mon, 2007-01-22 at 11:32 +1100, Andy wrote:
> > 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: 
> http://www.justlinux.com/forum/showthread.php?t=143973
> * Just booting tips: http://www.justlinux.com/forum/showthread.php?t=144294
> * Saikee's grub booting tips: 
> http://www.justlinux.com/forum/showthread.php?p=837905#post837905
> 

I want to mention that this is exactly what I do (add all other booting
as rootnoverify.

This a very flexable way to do things ... for example, if you have a
drive that contains all the parts to boot the 2nd OS, you can move it to
a new machine and point grub to boot it there very easily.

You can also easily add a 3rd or 4th or 5th OS, etc. 

More recently, I have been setting up VMs via VMware instead of setting
up dual boots, but this method is the one I personally use for dual
booting.
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