[CentOS] RAID problem when building new computer

[fred smith]

On Wed, Jul 22, 2009 at 10:13:38PM -0400, Rob Kampen wrote:
> fred smith wrote:
> >Hi all!
> >
> >I'm building up a new box and plan to use Centos 5 on it.
> >
> >i've got a pair of SATA 320 GB drives to make a RAID1.
> >
> >I'm trying to follow the "howto" on the centos wiki for making a
> >"partitionable RAID" installation.
> >
> >Given that my partition scheme has a separate /boot partition, while
> >the one in the HOWTO apparently does not, I've had to tweak the steps
> >just slightly. But they all succeed without any problems, including
> >watching mdadm create the mirrored pair.
> >
> >however, when I pop out the DVD (booted in rescue mode, per the HOWTO)
> >and reboot, it gets past the GRUB screen and gives me these errors:
> >
> >	Mount: could not find filesystem '/dev/root'
> >	setuproot: moving /dev failed: no such file or directory
> >	setuproot: error mounting /proc: No such file or directory
> >	setuproot: error mounting /sys: No such file or directory
> >	switchroot: mount failed: No such file or directory
> >	Kernel panic - not syncing: Attempted to kill init!
> >
> >I have no idea what these errors mean. I assume they all cascade from
> >whatever failure the first one is trying to inform me of. I don't see
> >"/dev/root" anywhere in any of the config files I changed, per the
> >HOWTO.
> >
> >I'd appreciate clues, hints, suggestions, etc.
> >
> >Thanks in advance!
> >
> >  
> >------------------------------------------------------------------------
> >
> >_______________________________________________
> >CentOS mailing list
> >CentOS at centos.org
> >http://lists.centos.org/mailman/listinfo/centos
> >  
> Looks like it is not finding /
> The boot partition and grub appear okay, thus you may want to look at 
> the /boot/grub/grub.conf file and check
> the kernel statement with root=/dev/md3
> this is where my root is.
> HTH
> Rob

grub.conf contains root=/dev/md_d0p3 in this context. But since raid isn't running at this point in the
boot process, should it be something else? this is what Ralph's HOWTO said to do...

BTW, here's the specific HOWTO: http://wiki.centos.org/HowTos/Install_On_Partitionable_RAID1

also, since I can't boot the system yet, I have to boot the dvd in rescue mode. when in rescue mode, how
do I start RAID? I don't know much of anything about mdadm, so all I know how to do is what's in the HOWTO,
which shows how to add a drive to an existing single-disk raid, and that takes 3/4 of an hour (or more) to
sync the two drives, every time I do it. since they're already synced, I should be able to just start it up
and have it recognize the pair, but having read the man page for mdadm it isn't obvious to me how to do that.

Thanks!

-- 
---- Fred Smith -- fredex at fcshome.stoneham.ma.us -----------------------------
                        The Lord is like a strong tower. 
             Those who do what is right can run to him for safety.
--------------------------- Proverbs 18:10 (niv) -----------------------------
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