[linux-lvm] Grub 1 vs 2

Oscar Dijkhoff admin at oscardijkhoff.nl
Fri Jul 30 17:54:59 UTC 2010

On vr, 2010-07-30 at 11:26 -0400, Stuart D. Gathman wrote:
> On Thu, 29 Jul 2010, Brian McCullough wrote:
> > I guess I didn't understand the implications of switching to Grub 2, because
> > I let Ubuntu 10.04 do so when I was trying to dual boot a Grub 1 machine that
> > I had.  Once it was finished, I could not find the old system at all, and the
> > menu.lst ( or grub.conf or whatever ) in /boot/grub seems to have no effect
> > on anything.  At least changes that I make seem to do nothing.
> > 
> > Certainly I can mount the LVs that comprised the old system, so I know that
> > the install did not overwrite the LVs that I did not tell it to use, but I
> > can not seem to boot the old system.
> Ubuntu installed a new grub, with config files in a new location, probably
> in the Ubuntu root filesystem.  Those are the only config files (that
> instance of) grub will use.  I've not used grub 2 yet.  Unlikely, but perhaps
> they renamed the config?  Check man pages.
> Possible approaches:
> 1) You could mount that Ubuntu filesystem in other oses to modify its menu.lst.
> 2) You could add a Chain entry to the Ubuntu grub to load the old grub1
>    in /boot/grub.  This will require reinstalling grub1 to the partition
>    boot sector instead of the master boot sector.
> 3) Reinstall grub2 to a partition boot sector, reinstall grub1 to the
>    master boot sector, and add a chain entry to grub1 to boot grub2.
> 4) Reinstall grub2 to reside in the /boot/grub filesystem, overwriting
>    grub1.  Mount that filesystem in Ubuntu and create symlinks as
>    necessary so that Ubuntu updates work properly.
> In all cases, before playing with all that, go burn yourself a copy of
> Super Grub on CD.  Very handy when your system is unbootable...
> Distro LiveCDs are also handy, but Super Grub is much faster when you
> just want to boot grub.

The configuration system for GRUB 2 is completely different than what it
was in GRUB. The menu.lst file now gets created automatically based on
other config files. Look at /etc/default/grub. Search the web for GRUB 2
configuration if you need more info.

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