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

[Tom H]

On Mon, Oct 12, 2009 at 8:12 AM, Goh Lip <g.lip at gmx.com> wrote:
> Tom H wrote:
>> 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.)


> Tom, won't it be easier for him at the grub> prompt to type
> configfile (hd0,3)/boot/grub/grub.cfg
> to boot up his sda3 9.04 partition if it is already in grub2?


I am not familiar with the "configfile" command (I just googled it and
will try it with grub2 when I have a chance; the link that I followed
also points to "cat (hd0,X)/boot/grub/menu.lst" so it may be possible
to do "ls (hd0,X)/boot" without "root (hd0,X)"; thanks).

I agree that it is easier since it is probably safe to assume that the
config on /dev/sda3 is correct.