Randem Systems Support Board

Check in drive manager and see if you can break the mirror. Being that one drive has failed I would believe that the mirror should have already been broken.
 
If you remove the bad drive then the system will reset itself and only have one drive.
 
There can not be only one drive in BIOS unless the other drive has had a hard crash you should still see it there. Anyway just remove drive and all should be ok.

I set up mirroring in XP over a year ago. now one of the drives is failed (ok, has failed). how can I boot from the lone mirror?  When it's the only drive connected BIOS says no boot device.