My photo and video library has grown beyond the capacity of my internal HDD and I want to move away from my convoluted system of multiple Aperture libraries. Instead, I want to have 1 Pro library and 1 Personal library, with the Aperture libraries sitting in my iMac's 1TB internal drive and all of the masters residing in an external. I'm new to RAID and have only begun to understand how it works. I'm hoping a kind and knowledgeable fellow MacRumors member will help me choose the best solution for my setup. I've come across the LaCie 6TB 2big Thunderbolt Series RAID Hard Drive which appears to do what I need. 1 - I want to have both internal drives mirror each other 100% so I always have 2 exact copies on site. 2 - I need a 3rd HDD that I will keep off site in my bank's safety deposit box. I think the first part will be straightforward. Set up RAID 1 and put my files on the drive and both HDDs will mirror each other. Am I correct so far? Now the second part, I'm not sure how this will work. Can I swap out a drive every week with the one held off site? Will RAID see the differences and go to work on matching the data or do I have to format the offsite drive, and then set it up to copy one of the on site drives? Because I'm going to be doing this pretty regularly, I don't want the mess and confusion of having to set this up every week. I know the DROBO might do what I need, but I'm not sure I'm prepared to spend $1K on just the device without any HDDs inside. How is the DROBO different than a traditional RAID?