"Oh damn...I didn't know this and I have 2x2TB drives waiting to be added to my array (once my backup to CrashPlan is complete), but I already have a 3TB drive in the array... Guess I'm going to be buying more drives! 4TB of spare HD is no bad thing; I can use it for cold storage. I think DSM should warn you about this before starting to create the array." - Jalada