Unable to do mdconfig(8) early in boot

I just updated my current system which had last been updated about
Aug. 7. Suddenly profile.sh fails to run because mdconfig is returning
an error:
mdconfig: ioctl(/dev/mdctl): Read-only file system

It looks like it is not writable until after root is done. Why?

Right now, profile.sh requires fsck and must be run before root. It
seems that starting it after root and before mountcritlocal works, but
there may be some subtleties that I am missing that makes this a bad
idea.

Is the inability to create an md device before root has run a problem or
something expected? 
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman_at_es.net			Phone: +1 510 486-8634