Without going into great detail, I've had tons of reliability issues using a single USB3 enclosure for my Time Machine and a boot drive. I currently have a 3TB NAS drive with two partitions a 2.25TB partition for TM and 750GB partition for a boot drive. The boot drive is made with Carbon Copy Cloner which runs a nightly job at 2am. Basically I need to separate the partitions so that they are are on their own physical drives which means buying a second 1TB NAS drive and moving the clone drive on to it. I could buy a second USB enclosure but I'd like to keep everything as tidy as possible by buying one enclosure that holds two drives and sees each separately. Does this fit the bill? If not, what would you recommend given the situation?