Serious GRUB booting problem after install Ubuntu 9.10beta for testing it.

[Joseph Cooper]

Hi, panicked list newbie here! So please excuse me if I'm not conforming to
the posting etiquette here, but this was the only site I could find where
someone seems to have a similar problem to me, and it is very urgent so I
decided to jump in!

I seem to have done something similar to the OP, I have Linux Mint 7 (i.e.
Ubuntu 9.04) installed on my laptop (a hard drive, not SSD, though I doubt
that makes any difference) and tried to install the Karmic beta on my
external USB HDD. Unlike the OP I had no other OSs on there, though the
FAT32 disk did have some data on it so I went for guided resizing. I'm
unfamiliar with the new Ubiquity and so had to skip back a stage in the
partitioner after a 2.5gb partition had already been made without me
realising, since that wasn't big enough; I then cereated another larger
partition, and it listed the 2.5gb as "free space". Not sure if that space
is still free or if this was the cause of my problem.

Anyway, like the OP, I get Error 17 when I boot with the external turned on,
though I do not get an option to continue, I have no options and must
hard-reboot. Again I get "no such disk" when booting with the external off,
and am given a grub rescue> prompt. I tried the grub rescue commands
mentioned but only the first one, ls, worked; I am told that "root is not a
valid command" or similar, no matter what I put in the (hd0,X). Trying any
of the other commands just returns another "no such disk". All my files are
still there on my hard drive, though I would very much like to resolve this
without having to reinstall.

Any idea why the root command isn't working for me, and what I can do to
boot back into Mint 7? At this point I don't care what happens to the
external and just want to be back where I was when I started! I had thought
I did the whole thing without touching my internal drive, but obviously
not...

Many thanks in advance,
Joseph

++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Quote: Tom H

Luis Maceira <luis_a_maceira at yahoo.com> wrote:

> I installed 9.10 beta for testing it on an external
> USB HDD partition (/dev/sdb7), and I have 9.04 on
> /dev/sdb5 (where the default GRUB stage2 is), I
> also have 9.04 on the internal SSD drive (partition
> /dev/sda3). Now I am not able to boot Ubuntu 9.04
> on my internal SSD drive.

> When I disconnect my external USB HDD the booting
> process gives me:

> GRUB loading...
> error: no such disk
> grub rescue>_

> When the external USB HDD is connected and I call
> the GRUB menu and it appears, the system (9.04) on
> the internal SSD appears normally on the GRUB menu
> (I think everything is OK) choose booting the SSD
> but then the warning:

> Error 17 : cannot mount selected partition
> Press any key to continue...
> (and return back to GRUB menu)

> From my working systems 9.04 and 9.10 on the USB
> HDD I mount the filesystem on the internal SSD and
> everything appears OK even the /boot/grub directory,
> so in my opinion the installer of Ubuntu 9.10 beta
> messed up with GRUB stage 1 on the MBR of the internal
> SSD and the way to the right partition /dev/sda3 is
> lost.

> Any way to revert this? without installing Ubuntu
> from scratch on the internal SSD.

Since you are at the "grub rescue" prompt when you try to boot from
your internal SSD and no external HD connected, you must have grub2
installed on your SSD.

grub rescue> ls

It should list your disk and its partitions.

grub rescue> root (hd0,X)
Where X is your "/" partition (or your "/boot" partition, if it is
separate).

grub rescue> ls /boot
To confirm that you have "rooted" the correct partition.
If you have, you should see your kernel, initrd, etc and the grub directory.
If not, do another "root (hd0,X)" and try again.

Once you have the correct "root (hd0,X)".

grub rescue> insmod /boot/grub/normal.mod
To go to the normal grub prompt.

grub> insmod /boot/grub/ext2.mod
To load ext2 module.

grub> ls /boot
If you cannot see the output of the previous "ls /boot" and cannot
remember the file names of the kernel and initrd.

grub> linux /boot/vmlinuz-2.6.31-13-generic root=/dev/sda3 ro
To load the kernel.

grub> initrd /boot/initrd.img-2.6.31-13-generic
To load the initrd.

grub> boot
To boot.

You should boot into your SSD install.

Once booted, you should run "grub-install /dev/sda" to ensure that
your SSD's grub.cfg is updated/corrected and you should then check it.

Then connect the HDD and run "update-grub" to add the two HDD installs
to the SSD's grub.cfg.

(I would also check that the device.map and grub.cfg disk references
correspond.)

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