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

Wed Jun 20 20:14:02 UTC 2012
Arun Khan <knura9 at gmail.com>

On Wed, Jun 20, 2012 at 10:57 PM,  <m.roth at 5-cent.us> wrote:
> Arun Khan wrote:

>> 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.

Using 'dracut'  I did create a new initramfs file per the instruction
in the wiki.

Nonetheless, assuming that the md module is missing in the new
initramfs, one would expect the boot to fail with /dev/sda and
/dev/sdb both connected to the system. The fact the system boots in
this case shows that the md driver is present.

See screenshot here <http://imagebin.org/217246>

>> 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?


Please see screenshot <http://imagebin.org/217263>

-- Arun Khan