[CentOS] CentOS 7 install on one RAID 1 [not-so-SOLVED]

So, it installed happily.

Then wouldn't boot. No problem, I'll bring it up with pxe, then chroot and
grub2-install.

Um, nope. I edited the device map from hd0 and hd1 being the RAID to
/dev/sda and /dev/sdb, then ran grup2-install. It now tells me can't
identify the filesystem on hd0, and can't perform a safety check, and
gives up.

What am I missing? Google is not giving me any answers....

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