Re: moving an installed Debian system onto RAID-1

[Nate Duehr <nate@natetech.com>]

Robert Waldner wrote:

> However, when I boot with "Linux root=/dev/md3 ext3" it can't find a 
>  valid ext3/ext2/reiserfs superblock on md(9,3). There's a couple lines 
>  right before that that tell me that md is autodetecting RAID arrays 
>  (can't copy/paste that for obvious reasons).
>
> Any hints/pointers? The various howtos etc. aren't all that 
>  helpful for this kind of problem.

If you're running an initrd kernel, you'll need to create a new initrd 
image that points to /dev/md3 instead of the physical disk.

mkinitrd -r /dev/md3 -o /boot/initrd-raid-X.X.X

And then point your bootloader at that initrd image.  I ran into this 
exact same error a few days ago.

I use GRUB, so my config ended up looking something like this when I was 
done. I have ability to boot from either disk alone or the RAID, but 
obviously if you boot from one of the disks you would have to be ultra 
careful to mark the other disk as "bad" in the MD arrary before 
rebooting with RAID support or things would get very corrupted/messy 
quickly.

(And yes before anyone gives me any grief I already know both disks are 
on the same IDE chain and controller which is dumb, but there is a 
reason for it.  Robert, in your case, replace the hdb's below with 
hdc's, if I read your message correctly.)

title           Debian GNU/Linux, kernel 2.4.26-1-k7 (RAID)
root            (hd1,0)
kernel          /vmlinuz-2.4.26-1-k7 root=/dev/md3 ro
initrd          /initrd-raid-2.4.26-1-k7.gz
savedefault
boot

title           Debian GNU/Linux, kernel 2.4.26-1-k7 (hda)
root            (hd0,0)
kernel          /vmlinuz-2.4.26-1-k7 root=/dev/hda3 ro
initrd          /initrd.img-2.4.26-1-k7
savedefault
boot

title           Debian GNU/Linux, kernel 2.4.26-1-k7 (hdb)
root            (hd1,0)
kernel          /vmlinuz-2.4.26-1-k7 root=/dev/hdb3 ro
initrd          /initrd.img-2.4.26-1-k7
savedefault
boot

title           Debian GNU/Linux, kernel 2.4.26-1-k7 (hda:recovery mode)
root            (hd0,0)
kernel          /vmlinuz-2.4.26-1-k7 root=/dev/hda3 ro single
initrd          /initrd.img-2.4.26-1-k7
savedefault
boot

title           Debian GNU/Linux, kernel 2.4.26-1-k7 (hdb:recovery mode)
root            (hd1,0)
kernel          /vmlinuz-2.4.26-1-k7 root=/dev/hdb3 ro single
initrd          /initrd.img-2.4.26-1-k7
savedefault
boot

Nate Duehr, nate@natetech.com