Question: Disk Mirroring preceding RAID?

Hi, Need help in settling argument...does disk mirroring (via hardware) predate RAID's mirroring capability? (I'm not interested in OS software implemented mirroring here.) Also, are there any hardware mirror methods that one could point to and say: this is not capable of being called any kind of RAID! (The argument in question is over the statement that "all hardware based mirroring is a form of RAID".) For example, is there any "stealth hardware mirroring" mechanism, where a drive watches the bus, and obeys writes, but nothing else? (This would be "drive-based" mirroring, as opposed to "controller- based mirroring") (Since RAID is controller-based, a drive-based mirroring mechanism would seem to be clearly not any kind of RAID.) thanks! Stan Stan Sieler sieler(a)allegro.com www.allegro.com/sieler/wanted/index.html www.allegro.com/sieler