One of the very few software RAID programs for Mac. I would read the requirements in the package very carefully, and follow them to the letter.
Conley SoftRaid superseded Apple Raid, and came bundled with the Macintosh G3 server.Compatibility
2.0.2 is compatible through Mac OS 8.1.
Softraid 2.2.2 is compatible with Mac OS 7.1 through 9.2.2.
Softraid 2.2.2 was released in 2000, and should be compatible with G4-based macs also, at least the early ones. G4 compatibility is mentioned at SoftRaid's website.