[CentOS] C7, mdadm issues

I've no idea what happened, but the box I was working on last week has a
*second* bad drive. Actually, I'm starting to wonder about that
particulare hot-swap bay.

Anyway, mdadm --detail shows /dev/sdb1 remove. I've added /dev/sdi1... but
see both /dev/sdh1 and /dev/sdi1 as spare, and have yet to find a reliable
way to make either one active.

Actually, I would have expected the linux RAID to replace a failed one
with a spare....

Clues for the poor? I *really* don't want to freak out the user by taking
it down, and building yet another array.

      mark