Figure software RAID under Ubuntu is good enough (?)
Yup, works great and is easy to recover from failures. You have to install the Server version if you want to set up the RAID config during install, then you can add the desktop GUI if you want after install.
Can anyone recommend a decent i7 or Xeon based system, smallest form-factor possible, capable of housing at least 4 x 3.5" drives ?
Chenbro makes a nice case (4x hot-swap bays) if you don't mind installing your own CPU&motherboard.
https://www.newegg.com/Product/Product.aspx?Item=9SIA4R86ME2329&cm_re=chenbro-_-11-123-173-_-Product




