I just ordered The Synology DS411J with 4 Hitachi 2TB 7200RPM Drives. This will be my first NAS. Right now my Itunes library is sitting at about 2TB. I want to use the NAS obviously for backing up my itunes library which currently is not backed up, and time machine. Ive been reading up on raids and I dont know if I should use the Synology Hybrid Raid, or Raid 5. What is the difference and benefits of these two? How much space will I have out of the 8TB that will be useable? I wanted the 3TB drives but they are just to costly right now. So later on I will swap them out as my demands increase.