I had a RAIDframe level 1 RAID with the first component marked as failed, e,g, component0: failed /dev/dkN: optimal and although the set was configured -A softroot, the kernel didn't configure raid0a as the root file system, presumably because the dk numbers didn't match. I was sitting in front of the console, so I could easily type raid0a etc., but this would have prevented an automatic boot.
I'm afraid little can be done about that weird situation?