I'm looking to add two 3TB HDD's and one 2TB HDD as storage attached to a 2 bay Synology DS212J NAS box. They will only be attached via the USB 2.0 connection. Each drive is prefilled with content, so I won't necessarily be transferring large amounts of data via USB 2.0. The 2TB drive is setup as a backup drive already. The new 3TB HDD's will be there just for storage, to be accessed randomly. These 3TB HDD's are WD Green's taken from individual, fan less external cases.