On 12/31/2009 11:27 AM, James Bensley wrote:
I can't say this with 100% certainty but I would of thought that it would been fine. I've lost my mdadm.conf (reinstalled OS) with a separate 4 disk RAID 5 array and re-assembled the array and carried on as if nothing had happened.
Yes, in general, you don't need the mdadm.conf at all. As long as the array is built out of partitions marked as type "fd: Linux raid autodetect".
However, whenever CentOS installs a new kernel and initrd image file, it creates (or uses?) an mdadm.conf file within the initial boot environment. Back when I was migrating a server to a new environment, I had to unpack the image, edit that copy of mdadm.conf, and then repack it all in order to get a proper boot.
So I suspect (but am not certain) that the ARRAY lines in /etc/mdadm.conf are useless on a CentOS system but that the ARRAY lines inside the initrd image file are the real ones used. But the former may be used to generate the latter when you install a new kernel.