I'm looking to build a RAID-5 or RAID-6 hard disk array to be used as a centralized backup location for my home network. I have a lot of 4-8GB DVD ISO files which I intend to serve over the network to my TV using DLNA or something similar. I need decent write times, fast read times, and preferably a way to connect this array to my network router over USB. I'll probably be using ext3/4 on it (I'd use btrfs if my router supported it :-[).
Is there a way to build a RAID array that is accessible over USB? I'm kind of new to this and most guides assume you're running a RAID array inside your machine. I need at least 5TB of space, and I need redundancy, so I prefer RAID-6. How can I go about accomplishing this?