GRUB badly broken during upgrade

[Kevin O'Gorman]

On Fri, Oct 5, 2012 at 8:01 PM, Kevin O'Gorman <kogorman at gmail.com> wrote:
> On Fri, Oct 5, 2012 at 6:47 PM, Kevin O'Gorman <kogorman at gmail.com> wrote:
>> On Fri, Oct 5, 2012 at 4:59 PM, Avi Greenbury <lists at avi.co> wrote:
>>> Kevin O'Gorman wrote:
>>>> On Fri, Oct 5, 2012 at 3:28 PM, Avi Greenbury <lists at avi.co> wrote:
>>>> > Kevin O'Gorman wrote:
>>>> >> I had a system with a working Ubuntu 11.04 and Xubuntu 12.04.
>>>> >> I went to upgrade the Ubuntu to 11.10, and all seemed well until I
>>>> >> went to reboot.
>>>> >> It got confusing after that.  It looked like all of the right kernels
>>>> >> were listed, but they all went to the same root.
>>>> >
>>>> > What do you mean by this? Each listing should generally be the same
>>>> > root (both by grub's definition of 'root' and the kernel's).
>>>>
>>>> When I had just installed Xubuntu, the grub menu would show its
>>>> 3.0.0-26 kernel at the first two lines, followed by memtest, then the
>>>> Ubuntu 2.6.x kernels with an explicit root for Ubuntu.  The 3.0.0
>>>> lines would boot to Xubuntu, and the 2.6 lines to Ubuntu.  I'd like to
>>>> get back to that state.
>>>
>>> I'm still not sure I understand. Just to be clear, your system and its
>>> kernels are all on the same volume? That being the case, when it
>>> worked you cannot possibly have had more than one of any of the things
>>> I can think of that I'd call 'roots'. That being the case, I don't
>>> think it matters what we call them :)
>>
>> Let me try to clarify.  I did indeed have two roots on the same
>> volume, abeit not simultaneously.  The GRUB menu had entries for both
>> of them that would put me in the system I chose.  In other words, it
>> was just multibooting two alternative Linux setups.  This was
>> accomplished by the Xubuntu 12.04 GRUB, which I can no longer access.
>>
>>
>>>
>>>> >> I got in a rescue mode, and tried another update-grub.  Again it
>>>> >> seemed to work, but now grub goes directly to
>>>> >>   grub rescue>
>>>> >> and I have no idea what to do there.  So I'm writing this on another
>>>> >> system, on which I'm not likely to upgrade the Ubuntu any time soon
>>>> >> 8o)
>>>
>>>
>>> Right now, on boot, your system goes straight to a grub rescue prompt?
>>> (as in the prompt is 'grub rescue>')? That implies a broken grub and
>>> the easiest way round that is normally to boot from a grub CD or DVD
>>> and reinstall (or inspect) it from there.
>>>
>>> The Super Grub Disk is popular and here:
>>>   http://www.supergrubdisk.org/
>>>
>>> But I've found that there's a few sets of hardware on which that wont
>>> boot but Grub 1 will. I've an ISO for that here:
>>>   http://avi.co/s/grub1.iso
>>>
>>> If you do get it to boot, could you let us know what you did? And, on
>>> trying another grub-install how you invoked it and what it said.
>>
>> I'll try the supergrub.  I don't want to get too far from what was working.
>
> I tried supergrub with no luck
>
> I've burned a supergrub disk, version 0.9799, the latest not-beta I could find.
> Its help did not do that much for me, so I fumbled around a bit.
> Because I have several partitions, I chose manual operation
> -  GRUB -> MBR & !LINUX! (>-2) MANUAL
> -  This gave me
> --      selectfile /grub/stage1 /boot/grub/stage1
> --      ERROR 15: File not found!
>
> So I tried
> -   !LINUX!| (>=2) MANUAL
> -   This gave me
> --      selectfile /boot/grub/menu.lst /grub/menu.lst
> /boot/grub/grub.conf /grub/grub.conf
> --      ERROR 15: File not found!
>
> So I tried
> -   (ROOT) !LINUX! (>=2) MANUAL
> -   This gave me choices
> --      It identified the systems on the two root partitions
> correctly.  The Xubuntu partition (hd0,1) failed, so I tried Ubuntu
> (hd0,6), which also failed, but here I'll give details (the two failed
> in very similar ways):
> --      It showed me the vmlinux files, I chose the most recent
> --      It showed me the initrd files, and I chose the matching one
> --      It started booting
> --      It gave up waiting for the root device and gave me some
> possible causes (I'm  not sure how to check on rootdelay= and root=)
> --      It complained about a disk being unavailable and gave me the
> UUID it was looking for
> --      Then it could not load the /lib/modules file it wanted
> --      and dropped me in busybox, which seems to be a simple shell
> running in a ramdisk.  It has no /dev/sd* entries, so it seems pretty
> useless.
>
> I booted an Xubuntu 12.04.1 live disk
> -  with blkid, I verified that the UUID it failed to find is (hd0,6)
> aka /dev/sdb7)  There are 3 drives in the system, but only one has a
> partition 7, so there was no confusion
> -  "grub-install /dev/sda" fails, complaining it "cannot find a device
> for /boot/grub (is /dev/ mounted?)"
> -  mounting /dev/sdb7 and chrooting to it does not fix this problem
>
> I'm out of ideas at the moment....
>
> ++ kevin

Well, not completely.  The Xubuntu install is really fresh, and I
could back up the few things I configured, so I've re-installed.  It
runs and my web site is back up.  My mind is at ease enough to let it
be while I'm out of town much of tomorrow.

I think I know what caused the problem:
Ubuntu 10.10 and Xubuntu 12.04 have somewhat different grubs.  It
shows in the way hard disks are named, for instance.
After installing 12.04 all was well.
But then I upgraded Ubutnu 10.04 to 10.10 and allowed its grub to fool
with things because its kernel was upgraded.  One thing led to another
and the two grubs destroyed each others' work.

If anybody knows what I did wrong with the supergrub attempt, I'd like
to make a note of it.
-- 
Kevin O'Gorman

programmer, n. an organism that transmutes caffeine into software.