[ale] SW RAID install problem - can't find root on raid at boot time

[Jeff Hubbs]

Danny -

That HOWTO you cited appears to apply to the 2.4-era raidtools, which
have since been supplanted by mdadm.

On the other hand, if you look at the doc I linked to in the original
message (http://tinyurl.com/mauwd), specifically that grub.conf example
that looks like

    title=Gentoo
    root (hd0,0)
    kernel /boot/kernel root=/dev/md3


you can see that they're doing nothing of the sort - just using /dev/mdX
as the root device.

*My* grub.conf looks like this in its entirety:

    default 0
    timeout 10

    title Virtual Hosting Platform (default): Xen 3.0.2 /
    vmlinuz-2.6.16.26-xen-dom0
    root   (hd0,0)
    kernel /xen.gz dom0_mem=256M
    module /vmlinuz-2.6.16.26-xen-dom0 root=/dev/md1

    title Normal Non-Xen kernel (maintenance/emergency):
    kernel-2.6.17-gentoo-r4
    root (hd0,0)
    kernel /boot/kernel-2.6.17-gentoo-r4 root=/dev/md1

You can see that the first entry is meant to bring up the Xen dom0.  The
other one is a straight kernel, identically configured in the ways that
count. 


Danny Cox wrote:
> 	Well, the auto-detect isn't working.  When it works correctly, you'll
> see something like this:
>
> md: Autodetecting RAID arrays.
> md: autorun ...
> md: considering hde1 ...
> md:  adding hde1 ...
> md:  adding hdb2 ...
> md: created md0
> md: bind<hdb2>
> md: bind<hde1>
> md: running: <hde1><hdb2>
> md: raid1 personality registered for level 1
> raid1: raid set md0 active with 2 out of 2 mirrors
> md: ... autorun DONE.
>
> 	I think the problem is that root is mounted first, and then LATER, RAID
> autodetect is invoked.  So, /dev/md1 isn't available yet.  There's a
> trick to this.  At one time you mounted one disk of the array just to
> get things going, and later, when the array was activated, a
> "switchroot" was done to establish the root fs on the RAID.
>
> 	See http://tldp.org/HOWTO/Software-RAID-HOWTO-7.html#ss7.3 for specific
> information on setting up GRUB to use it.  Sorry, I don't remember if
> you said you're using GRUB or not.  Hope this helps!
>
>