Bug#548648: grub-pc jumps straight to rescue and prints error: no such disk / file not found

[Josip Rodin]

Hi,

I've reported this bug in the Debian BTS, to no avail, so I'm cc:ing the
upstream address for help.

I've got two disks and a software RAID setup on the partition that holds
the /boot directory. I have several Linux software RAID partitions, based
on this scheme:

sda2+sdb2	-> Linux amd64 /
sda3+sdb3	-> Linux i386 /
sda4+sdb4	-> Linux swap
sda5+sdb5	-> Linux /home

The first two become md0, differentiated by old GRUB menu entries -
Linux parameters raid=noautodetect and md0=first,second ... settings.
The second two become md1 and md2, respectively, and the fourth array
is simply left unassembled on the non-applicable architecture.

On the amd64 partition I installed the new grub (1.97whatever), using all of:

# grub-install /dev/md0
# grub-install /dev/sda
# grub-install /dev/sdb

All of those reported the identical message:

Installation finished. No error reported.

Yet after a reboot I now still can't get any further than:

Welcome to GRUB!

Entering rescue mode...
error: file not found
grub rescue> 

Since this is my primary development machine that is wedged, this is most
unpleasant...

I had also tried to add --modules="ext2 raid mdraid ntfs" to make sure it
has all the drivers early, but that didn't help much.

Based on information at
http://grub.enbug.org/Manual#head-d782c3ed07197a089c4fdf66abce08744adcc0eb
I tried to run "help", but that says it's an unknown command. D'oh!

I tried to get insmod /boot/grub/normal.mod, but that repeated the
file-not-found error.

I then tried an assortment of commands guessing names from /boot/grub/*.mod
files and I seem to have the command "ls" which outputs all the partitions
in a space-separated list, including (md0), (md1), (md2), (md3), as well as
all the numerous (hd*) entries. So it seems to have assembled all four
software RAID arrays, but I don't know which is which.

The command "set" also works, and it displays:

prefix=(md0)/boot/grub
root=(md0)

Because of my non-trivial setup, I'm guessing something related to md0
initialization confused grub, but I've no idea what because it's not saying
anything useful.

So I tried guessing my way out of it - I manually set root and prefix
variables to md1, tried to insmod normal.mod, it repeated the file not found
error. Tried it with md2, it said unknown filesystem - so that might be the
swap. Tried it with md3 - ha! it executed something, cleared the screen and
showed me the intro lines, but again only the rescue> shell. Running "set"
there displays a few more variables, but still no "help" or anything.

I'll keep trying, but any hints would be most appreciated.

( More supplemental information can be found in the original report
http://bugs.debian.org/548648 )

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