CentOS - Sep 2017 - CentOS 7 on PPC64le booting from a MD RAID volume

I've been trying to install CentOS 7 AltArch ppc64le onto a new Power 8 
system and I want to configure mdraid for the volumes.? I can get 
everything working if I install to a single disk, but when I configure 
for RAID 1, the system fails to boot.
So, is mdraid1 supported for booting a Power 8 system?
Tom Leach
leach at coas.oregonstate.edu