The RX1217 is a 12-bay storage expansion unit that adds capacity to a Synology RackStation — it has no compute of its own and works only when connected to a host NAS, letting a project outgrow a single chassis without a second host. Its 12 hot-swappable bays each take a 3.5" SATA hard drive, 2.5" SATA hard drive or 2.5" SATA SSD. The unit connects to the host RackStation via an included Infiniband cable for maximum data throughput, and three 80mm fans cool the drives and the unit itself. A single 500W power supply powers the unit and drives — the one feature that sets it apart from the RX1217RP, which carries two redundant 500W supplies for uptime if a PSU fails. It's built specifically for Synology's RackStation range.