I just found this project by browsing the mergerfs documentation. It claims to be an opensource fork of the Unraid software that makes it so flexible. The documentation isn't great, but has all the basic info to get going. It works kinda like Snapraid in that each disk has it's own filesystem and parity is calculated across all of the drives, but it happens in real time (unlike with snapraid).

Thoughts? comments? Would you trust this with important data?