[CentOS] I need help with GRUB

Al Sparks data345 at yahoo.com
Mon Sep 1 22:44:35 UTC 2008


--- On Mon, 9/1/08, Lanny Marcus <lmmailinglists at gmail.com> wrote:

> From: Lanny Marcus <lmmailinglists at gmail.com>
> Subject: Re: [CentOS] I need help with GRUB
> To: "CentOS mailing list" <centos at centos.org>
> Date: Monday, September 1, 2008, 9:53 AM
> On Sun, Aug 31, 2008 at 11:31 PM, Sadaruwan Samaraweera
> <slinuxworld at gmail.com> wrote:>
> > On Mon, Sep 1, 2008 at 9:55 AM, Ian Forde
> <ian at duckland.org> wrote:
> >>
> >> On Mon, 2008-09-01 at 09:47 +0530, Sadaruwan
> Samaraweera wrote:
> >> > Hello,
> >>
> >> >    And the problem that I'm having is
> with my two Linux distros. Ive
> >> > installed CentOS & Windows in my SATA HDD
> and I've used my complete
> >> > 40GB PATA HDD for Ubuntu. Well all OS's
> work fine with out any
> >> > problems but when I want to boot into CentOS
> I've to select the SATA
> >> > as my booting HDD from the BIOS if I want to
> go to Ubuntu the I've to
> >> > select my PATA as the default HDD from the
> menu. So what I want to do
> >> > is I need to add Both distros in to one GRUB
> boot loader and the other
> >> > thing is that both grubs that I've on
> both HDD s only detects the
> >> > windows Partition not the Linux partion. So I
> need to to know how to
> >> > add bothe Linux versions I've into one
> GRUB. I want to use the SATA
> >> > HDD as my default HDD.
> >>
> >> You'll want to merge the grub boot stanzas
> into one file, apply it to
> >> one (or both) of the drives, and keep it in sync
> when you do kernel
> >> updates (because those affect the grub menu)...
> This way, you won't have
> >> to change the BIOS setting.
> >>
> 
> > OK, thx for the quick reply but I realy don't know
> how to do that can any
> > one help on that note.
> 
> 
> Possibly what you need to do is add another entry in your
> /etc/grub.conf file, on the HD you boot from.  Below is 
> mine.
> 
> [lanny at dell2400 ~]$ sudo cat /etc/grub.conf
> Password:
> # grub.conf generated by anaconda
> #
> # Note that you do not have to rerun grub after making
> changes to this file
> # NOTICE:  You have a /boot partition.  This means that
> #          all kernel and initrd paths are relative to
> /boot/, eg.
> #          root (hd0,2)
> #          kernel /vmlinuz-version ro
> root=/dev/VolGroup00/LogVol00
> #          initrd /initrd-version.img
> #boot=/dev/hda
> default=0
> timeout=5
> splashimage=(hd0,2)/grub/splash.xpm.gz
> hiddenmenu
> title CentOS (2.6.18-92.1.10.el5)
>         root (hd0,2)
>         kernel /vmlinuz-2.6.18-92.1.10.el5 ro
> root=/dev/VolGroup00/LogVol00 rhgb quiet
>         initrd /initrd-2.6.18-92.1.10.el5.img acpi=off
> title CentOS (2.6.18-92.1.6.el5)
>         root (hd0,2)
>         kernel /vmlinuz-2.6.18-92.1.6.el5 ro
> root=/dev/VolGroup00/LogVol00 rhgb quiet
>         initrd /initrd-2.6.18-92.1.6.el5.img acpi=off
> title CentOS (2.6.18-92.1.1.el5)
>         root (hd0,2)
>         kernel /vmlinuz-2.6.18-92.1.1.el5 ro
> root=/dev/VolGroup00/LogVol00 rhgb quiet
>         initrd /initrd-2.6.18-92.1.1.el5.img acpi=off
> title Windows XP
> rootnoverify (hd0,0)
> chainloader +1
> [lanny at dell2400 ~]$
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It's handy that someone posted their grub file.

The answer to your question/situation might be complicated by the fact that you use you have been changing your boot up disk in your BIOS.

But the thing to look for in your grub.conf file is:

> title CentOS (2.6.18-92.1.1.el5)
>         root (hd0,2)
>         kernel /vmlinuz-2.6.18-92.1.1.el5 ro

Note that this example includes an entry for a hard drive:

>         root (hd0,2)

That entry points to the "first" hard drive, third partition.  If you
have 2 hard drives, and you wanted to boot off the "second" drive
first partition, you might use:
        root (hd1,0)

You basically want to look at the grub configuration for each OS on
each hard drive you installed it on, and in consolidating them, "cut
and paste" entries from what you want to be your secondary drive to
your primary boot drive.

Again, this is only using the above grub.conf as an example.  If you
have SCSI hard drives instead then probably the grub.conf will show
something like:
       root (sd0,2)

So it's important to look at your grub.conf and make modifications.

Hope this helps.  If you want more specific advice, then post BOTH
grub.conf files, and tell us which one will be from what you want to
be your secondary drive, and what you want to be your primary drive
(in BIOS).
    === Al


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