[PLUG] Reliable storage on a shoestring

[Fedor Pikus]

On 8/7/05, Eli Stair <eli.stair at gmail.com> wrote:
> 2) RH (and some other distros) don't install GRUB to the bootsect of
> the drives properly... if your install goes fine, but you can't get
> the OS to boot post back here (presuming you have another box ;)

First of all, you cannot boot from software RAID-5, only from a mirror
RAID (RAID-1).
As far as GRUB, any distro which relies on grub-install won't be able
to install GRUB on soft-RAID. I don't think GRUB documentation
mentions how to do it either. But there is a way, you have to get to
the grub prompt and do it manually. Here is how to do it for a RAID-1
built from hda1 and hdb1 (# is shell prompt, grub> is GRUB prompt,
everything else is what GRUB prints out):

# grub
grub> root (hd0,0)
 Filesystem type is ext2fs, partition type 0xfd 
grub> setup (hd0) 
 Checking if "/boot/grub/stage1" exists... yes
 Checking if "/boot/grub/stage2" exists... yes
 Checking if "/boot/grub/e2fs_stage1_5" exists... yes
 Running "embed /boot/grub/e2fs_stage1_5 (hd0)"...  16 sectors are embedded.
succeeded
 Running "install /boot/grub/stage1 (hd0) (hd0)1+16 p
(hd0,0)/boot/grub/stage2 /boot/grub/grub.conf"... succeeded
Done.

grub> root (hd1,0)
 Filesystem type is ext2fs, partition type 0xfd

grub> setup (hd1) 
 Checking if "/boot/grub/stage1" exists... yes
 Checking if "/boot/grub/stage2" exists... yes
 Checking if "/boot/grub/e2fs_stage1_5" exists... yes
 Running "embed /boot/grub/e2fs_stage1_5 (hd1)"...  16 sectors are embedded.
succeeded
 Running "install /boot/grub/stage1 (hd1) (hd1)1+16 p
(hd1,0)/boot/grub/stage2 /boot/grub/grub.conf"... succeeded
Done.

grub> quit

If you look carefully, you're actually booting from either half of the
mirror. Your /etc/grub.conf should reflect this:

default=0
fallback=1
timeout=5
splashimage=(hd0,0)/boot/grub/splash.xpm.gz
hiddenmenu
title Fedora Core (2.6.12-1.1372_FC3)
        root (hd0,0)
        kernel /boot/vmlinuz-2.6.12-1.1372_FC3 ro root=/dev/md0
        initrd /boot/initrd-2.6.12-1.1372_FC3.img
title Fedora Core (2.6.12-1.1372_FC3) Mirror
        root (hd1,0)
        kernel /boot/vmlinuz-2.6.12-1.1372_FC3 ro root=/dev/md0
        initrd /boot/initrd-2.6.12-1.1372_FC3.img


-- 
Fedor G Pikus (fpikus at gmail.com)
http://www.pikus.net
http://wild-light.com