[svlug] Upgrading to grub2

[Ivan Sergio Borgonovo]

On Sun, 6 Feb 2011 22:26:46 +0000
Sanatan Rai <sanatan at gmail.com> wrote:

> Folks,
>    I just upgraded two of my home systems to Squeeze.
> 
>    As part of the upgrade, I get to use grub2. Both were running
> a mostly Lenny system with a few things from testing (eg emacs).

>    During the upgrade of the first system (64 bit m/c), I got the
> config screen from grub2 and chose /boot. It complained about
> installing on a partition other than the MBR. Now this system
> boots into grub but doesn't seem to see anything. How do I fix
> this?

>    The second system booted up, asking to `chain load to grub2',
> booted up thereafter, and asked to run upgrade-from-grub-legacy.
> When I run that, I get a screen similar to the first system, and
> got the same complaint (ie installing to a partiction other than
> MBR). I then reran it and chose all partitions, and got the same
> complaint. I am now scared to reboot this machine as am afraid it
> would render it unbootable.

Most of the problem I had were related to grub missing to guess
where my /boot and / were. At times LVM, DM and soft RAID had been a
problem.
If this is the problem you're facing you may still be unable
to boot with not too much effort since you can edit those lines after
boot in grub editor (e).

To check if this could be the culprit look at /boot/grub/grub.cfg and
check if Debian tools where smart enough to guess where your root
and /boot are.
That file will be overwritten by update-grub, that actually call
grub-mkconfig.

The most important files to edit grub configuration are:
/boot/grub/device.map
/etc/default/grub
/etc/grub.d/

/boot/grub/device.map may help grub to understand where your /
and /boot are. You may have to manually edit it if grub-mkdevicemap
fail to produce a working one.

-- 
Ivan Sergio Borgonovo
http://www.webthatworks.it