In using Synolog's online RAID Calculator I see that if I were to say fill a DS1019+ for example, with five 6gb drives, that I would end up with 24GB of space on the combined four drives and that one 6GB drive would be "Used For Protetion". I guess that "Used for Protection" is another way of saying that all that's in the 24GB of space is on the 6GB of the Used For Protection Drive ? Is that what it means. And if so, how does 6GB hold 24GB of data? Is is compressed?