Use vortexbox (vortexbox.org). Its free, open source. Easy to build using a lower power, fanless motherboard (e.g.J1900 series boards, ASROCK, ASUS, Gigabyte). Use a 'pico' power supply module and 12V brick. Most motherboards have 4 SATA sockets so you can use 4 drives. This gives you a media...