While I definitely sympathize with the desire here, mirrored disks are almost always the best way to go. It has saved my butt just in my home setup a couple of

While I definitely sympathize with the desire here, mirrored disks are almost always the best way to go. It has saved my butt just in my home setup a couple of times, most recently when a power connector got loose and started shutting a disk on and off basically at random. Mirrored disk mean quick recovery from such scenarios and relatively-limited impact during degradation. My opinion after trying both parity-checked redundancy and true mirrored redundancy is that any serious data storage should be strictly on mirrored volumes (preferably with disks of substantially different ages so you don't risk them dying within a couple weeks of each other, possibly before a replacement gets installed). I once read "50% storage efficiency is plenty, don't be greedy". Although painful for the home user, that seems like the right attitude to take for important stuff, especially as volume sizes increase. It can be a very slow and very fraught process to recover several TBs from parity data.