Summary: I purchased this raid in a 2x500gb configuration and also purchased two additional 500gb drives to fully populate it. Before ever powering it on, I inserted the additional drives hoping that what I read was true, that it would automatically configure itself to use them. Sure enough, once I installed the software on my computer and plugged the NAS in, it showed the first two drives as usable while it initialized the two new ones. Once they were initialized, they were automatically added to the RAID...couldn't have been simpler. File transfers were very straightforward, just a matter of mounting the shares that you set up in the wizard. Even pluggin in a USB drive was a painless affair. All in all, I am exceptionally pleased with this unit and wouldn't hesitate to recommend it to someone looking for a little peace of mind for their digital memories.