Update-grub does not handle dual-disk dual-boot well

[Sergei Genchev]

I had a PC with other OS installed on it. Debian proper but that does not
really matter. What matters is that I had an existing grub install. I added
another hard drive and installed Ubuntu on it. After reboot I could not boot
into Ubuntu (or, strictly speaking, I can from grub command line but there is no
Ubuntu boot menu entry).
 The reason is that Ubuntu creates new /boot/grub/menu.lst with correct entries,
including existing Debian install but since it being installed on a second hard
drive - /dev/hdb in my case - after rebooting grub finds menu.lst on /dev/hda
first and uses it instead. menu.lst on /dev/hda is not changed by install so I
only have my old grub menu.
 Same thing when I upgrade kernel from Ubuntu - menu.lst is updated on hdb and
upon rebooting grub would not see new menu entries.

 I am not exactly sure how this problem should be handled. My Very Ugly Hack was
to change update-grub so it mounts partition on /dev/hda and copies menu.lst
from /boot/grub from one drive to another. This works for me - hardcoded
partitions etc. but obviously it would not work for everyone.
 Maybe creating /etc/fstab entry during install for old partition - noauto
option or something. Setup does find existing grub install so it should know
where to look. Then make update-grub and/or grub-install mount it and look for
grub installation there.

 This may not even qualify as a bug - maybe a wishlist...

[Matt Zimmerman (mdz)]

grub should load the menu.lst from whatever was the root device at the time
grub-install was run

[Tormod Volden (tormodvolden)]

Sergei, you can fix this by opening a grub command shell (press c) and then find the right root partition with "root (hdX,Y)" - trial and error will do for X and Y, or let "find" help you. Then "setup (hd0)".