[CentOS] CentOS 6.2 on partitionable mdadm RAID1 (md_d0) - kernel panic with either disk not present

Wed Jun 20 17:27:45 UTC 2012
m.roth at 5-cent.us <m.roth at 5-cent.us>

Arun Khan wrote:
> On Wed, Jun 20, 2012 at 10:06 AM, Arun Khan <knura9 at gmail.com> wrote:
>> On Wed, Jun 20, 2012 at 1:00 AM,  <m.roth at 5-cent.us> wrote:
>> .... snip ....
>>> For one thing, edit grub.conf and get *rid* of that idiot rhgb and
>>> quiet,
>>> edit the kernel line in grub, and add rdshell at the end, so you boot
>>> into grub's rudimentary shell if/when it fails, and you can look
around and
>>> find what it's seeing.
>> Will try your suggestion and report back.
> Reboot the system with disk1 removed, the kernel boots, the 'md'
> driver  tries to bind sda.  At this point the systems seems to hang
> for a few seconds and then 'dracut' reports that it cannot find
> /dev/md_dop1 (the root partition)
>          dracut Warning: No root device "block:/dev/md_d0p1" found
> Console image pasted here <http://imagebin.org/217229>

At this point, I'm starting to wonder if the initrd.img has the drivers
for software RAID. You *might* need to rebuild that.
> In the "rdshell" environment I can see that /etc/mdadm.conf is defined
> but beyond this I don't know what to look for.
> Changing the Partition Id for the RAID1 partitions to 'fd' does not help.
> Any further suggestions and/or comments?

What devices are there in /dev/? /dev/sd? /dev/md?