As I’ve written above, the NAS offers three USB 2.0 and two eSATA ports for external devices. The latter interface is almost as fast as the internal HDDs. Unfortunately, you cannot integrate eSATA drives into RAID arrays. You can only access them via an appropriate network folder. The same goes for USB drives. When you connect an external drive to the NAS, resources called USBDiskN and eSATADiskN are created where N is the volume number in the order of identification. You can specify any access rights for these folders and they will keep on working when you unplug and connect a new device.
USB hubs are not supported, but three ports should be enough even considering a printer and a UPS. Multiple HDD partitions are supported, too. The NAS can work with FAT, NTFS, EXT3 and EXT4. If necessary, you can format your external drive using the NAS’s web-interface.
If you plug your drive into the front USB port, you can then press the special button to copy data from and to the drive. Copying is done with a NAS resource specified in the settings or into a folder created specially for each such operation. A synchronization mode is available for this feature.
The TS-219P can serve as a print-server for USB printers. Scanners in all-in-ones are not supported.
You can also connect a UPS into a USB port to correctly shut the NAS down in case of a power failure. The system can start up automatically later if its power supply is restored. Many UPS models from APC and compatibles are supported. You can find the entire list on the QNAP website. You can use SNMP devices, too.