I'm looking into a new storage system for my rMBP based photography studio. I use Weston Digital 3tb USB 2 disks for time machine and for Lightroom library manual back ups. This is a cheap and easy system and Speed is not important for these things, as I work them overnight. However: I'm looking at a Pegasus2 R4 disk array. My thinking is that I could set it up in RAID 10, and then use it as my main 'completed project' libraries. This would free the mega fast PCIe on my MB to be used as just the system disk, and as my current project disk (scratch disk). RAID 10 would be both fast and redundant. Another extra back up strategy, and super fast access to back catalogues. All in a fairly portable, easy to use, future proof (potentially a nMP on the distant horizon) package. It's not that cheap. Is it overkill? Another question I would like to know is, is there a limit to the size (in Tb) of the disks I put inside? Anyone got any thoughts?