Software RAID1

Paul Tansom paul at
Mon Aug 20 16:24:09 UTC 2007

** Brian Fahrlander <brian at> [2007-08-17 19:41]:
>     In a perfect world, I'd stick the root and /home onto two huge
> whopping RAID drives, but the inability to do it at install time has
> always held me back...but surely it won't be long- our developers are
> fabulous!
** end quote [Brian Fahrlander]

It is already there if you use the alternate CD. I've installed Ubuntu
6.06 LTS straight onto a RAID mirror using the 64 bit server CD. You do
have to do the partitioning manually, as in creating the identical set
of partitions on each drive and then pairing them up and setting the
mount points, but it is straigh forward to do. I was doing the same with
Debian from 3.1 onwards iirc, and the alternate CD pretty much uses the
Debian installer I believe (OK, ready for somebody to shoot me down in
flames on that one!).

** Below is from memory, so use with caution and have a boot CD handy **

On the subject of fail over booting, I found that, given I am booting
off a RAID mirror it made sense to add duplicate entries in the menu.lst
file, the main ones quote the root as (hd0,0) and the secondary ones
quote (hd1,0) as below:

title           Debian GNU/Linux, kernel 2.6.8-3-686 (Disk 2)
root            (hd1,0)
kernel          /boot/vmlinuz-2.6.8-3-686 root=/dev/md0 ro
initrd          /boot/initrd.img-2.6.8-3-686

I then installed GRUB into the MBR on both HDs using the setup command
from the grub console:

grub> setup (hd1)

You can check the mapping GRUB uses for your devices by finding where
youre stage1 file is using:

grub> find /boot/grub/stage1

Interestingly mine now comes up with 4 entries for that as it not only
finds /boot/grub/stage1 on my / partition, but also
/var/boot/grub/stage1 on my /var partition. I don't remember that

My setup may be regarded as a little odd though as both my HDs are
running off a PCI card and not the motherboard IDE (due to the
motherboard being too old to support the capacity of the drives). This
means my file looks like this:

(hd0)   /dev/hde
(hd1)   /dev/hdg

** I'll repeat that this is from memory as I can't find my notes for
some bizarre reason. I'll now find them and see the errors in my
description !! **

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