update-grub help

[Tom H]

On Tue, Jun 1, 2010 at 12:38 PM, Tom H <tomh0665 at gmail.com> wrote:
> On Tue, Jun 1, 2010 at 12:20 PM, Dave Howorth
> <dhoworth at mrc-lmb.cam.ac.uk> wrote:
>> Tom H wrote:
>>> Try:
>>>
>>> Create a device.map in Ubuntu with the same content as the OpenSuse's
>>> or the equivalent /de/disk/by-uuid values and save it (for example) in
>>> /root rather than in /boot/grub.
>>
>> I actually already tried copying the suse device.map over the ubuntu one
>> but it made no difference. grub still doesn't see hd6.
>>
>>> Run (in Ubuntu)
>>> grub-setup --root-device='(hd0)' --device-map=/root/device.map /dev/sda
>>
>> I'll give it a try though.
>
> Oops. No /dev/sda at the end... Sorry.
>
> So:
> grub-setup --root-device='(hd0)' --device-map=/root/device.map
>
> Copying it over is not enough. Hopefully using it with grub-setup will
> allow grub to see your OpenSuse drive at boot.

Was double-checking the command and it is wrong.

Run either
grub-setup --root-device='(hd0,X)' --device-map=/root/device.map '(hd0)'
where X is X of the sdaX on which /boot resides
or
grub-setup --device-map=/root/device.map '(hd0)'

Before you do this you could check whether the new device map file
allows you to find the OpenSuse partition with grub-probe with
grub-probe --device-map=/root/device.map --target=drive --device /dev/hdg
which should output (hd6), assuming that /dev/sdg is the OpenSuse disk.