This article is from the storage FAQ part1, by Rodney D. Van Meter with numerous contributions by others.
Pinnacle Micro has been advertising what they call the Orray -- essentially RAID done with removable magneto-optical disk drives. They claim sustained transfer rates up to 8 MB/sec., which seems implausible given that it's only four drives, and even HP MO drives are below 2 MB/sec. sustained. Apparently no redundancy in the system for that configuration (so I guess my ROAT designator is a misnomer), but it should be generally less necessary for MO than magnetic disk (drive failures normally don't result in the destruction of data or media). --rdv, 94/7/20