So I am switching from a MyBook Live Duo to a 4 Bay QNap Nas drive with four 2TB drives for a total of 8TBs. I've only ever had experience with a RAID 1 configuration, and now I'm using a RAID 5 configuration. Can someone please explain how I have over 5 TBs of available space. My understanding is RAID 5 is more secure, but in a RAID 1 configuration I only have access to half of the total space. Why does RAID 5 give me more?