CENTOS boot over raid partition

[Thomas Neumann]

Uhm. Don't do that. The canonical solution is to mount sda1 directly as a
normal filesystem and manually sync sda1 to sdb1 after a successfull boot.

Everything else is creating a dependency problem between initrd, md and
whatever filesystem you're using. It could be wrangled into a working by
using Lilo and fixed blocklist maps, but who's still using LiLo today?