I suppose in principle you could partition a drive n ways the run RAIDZ1? Though performance would probably be mediocre and there'd be some oddities.

Occurs to me know that as a practical matter perhaps raw storage will solve this for a lot of people. The pace of increase in storage/$ still seems to be steady, and in turn continues to mean more and more people trivially have their total needs exceeded. At some point may be perfectly reasonable to throw half at redundancy?