Bug#500157: grub-common: no such disk after un- and replugging disk belonging to RAID1 array

[Paul Menzel]

Dear Felix,


I tried it out this morning with even less success.

Am Freitag, den 26.09.2008, 18:56 +0200 schrieb Felix Zielcke:

Am Donnerstag, den 25.09.2008, 18:34 +0200 schrieb Paul Menzel:

> wanting to reinstall something I unplugged one of the two disks in the
> RAID1 array as a backup. Anyway I just accessed (cryptsetup luksOpen the
> md1 "partition")  the still connected disk and did not write anything
> onto it.
>
> After that a connected the other disk and got
>
> Welcome to GRUB !
>
> Error: no such disk
> Entering rescue mode...
> grub rescue>
>
> I could not find anything regarding to grub rescue on the net. ls does
> show (md0) (md0) (hd0) (hd1) (hd0,0) and so on.
>
> The strange thing is if I just leave either one of the two drives
> connected GRUB is showing up as it used to.
>
>
> Do you have any idea what caused this and how this can be fixed?

Did you do grub-install with ..24-10 or at least ..24-9?
In 24-9 there was a little RAID fix from me included.
People do forget that they have to really update grub by hand.

$ sudo grub-install --no-floppy /dev/md0
Installation finished. No error reported.
This is the contents of the device map /boot/grub/device.map.
Check if this is correct or not. If any of the lines is incorrect,
fix it and re-run the script `grub-install'.

(fd0) /dev/fd0
(hd0) /dev/sda
(hd1) /dev/sdb

Here is the output of the mdadm command from the thread of your patch.

    Number   Major   Minor   RaidDevice State
       0       8        1        0      active sync   /dev/sda1
       1       0        0        1      removed

Now it even got worse and GRUB is not even starting from this one
plugged in disk.

Error: no such disk
Entering rescue mode...
grub rescue> ls
(hd0)
grub rescue> root (hd0)
(hd0): Filesystem is unknown.
grub rescue> insmod normal # got that from another bug report
Error: no such disk
grub rescue> lsmod # abbreviated
[…]
raid
biosdisk
ext2
fshelp

Before grub-install ls showed
(md0) (md1) (hd0,1) ...

Not knowing what to do, I unplugged this disk (say A) and plugged in
the second one (say B). GRUB showed up and I thought everything is
fine. But then a user with no administrative privileges started and
used the computer. After a restart GRUB does not work anymore and
shows

Error: unknown filesystem
Entering rescue mode...
grub rescue> ls
(md1) (md0) (hd0) (hd0,1) (hd0,2)
grub rescue> root (md0)
(md0): Filesystem is unknown
grub rescue> root (md1)
(md1): Filesystem is unknown
grub rescue> root (hd0) # expected output!?
(hd0): Filesystem is unknown.
grub rescue> root (hd0,1)
(hd0,1): Filesystem is ext2
grub rescue> root (hd0,2) # expected, since encrypted lvm
(hd0,2): Filesystem is unknown.

I am even more puzzled about this incident and have no clue how this
could have happened.

> Else I don't have yet a clue for this.

Can you give me a int how to use a USB memory stick to boot a system
with? I just found howtos referring to grub legacy. And the IRC
channel #grub on irc.freenode.org was not active as probably expected
to this time on the weekend.


Thanks a lot,

Paul