For important data (images, documents, etc.) I would recommend a RAID. However, you can also connect an external HD via SATA and on data secure (runs with me also without any problems).
To secure: Super easy to set via the software - Regular backup in live situations (for example, images) is working properly. Played image on the server - a few seconds later it is backed up to the external HD. Also backups of all directories in the weekly or daily rhythm can be adjusted.
The device is in operation not very warm (according to the monitoring so about 35-40 degrees (CPU)) As a result, the fans do not run so fast and so reasonably quiet. For operation in the living room that is not recommended. My server is located in a plant room and is housed in a small server rack. Here he performs his work inconspicuously.
The software QNAP is veratändlich for the home user, but goes beyond my needs go far. I use eg even the server for my MP3 collection and can order anywhere in the house via a LAN (or WLAN) to access my music library. Also per app (QNAP) from the smartphone the music is available. More App's for control and Überachung there QNAP free. So all what you need (or may not ;-).
The hunger for energy mE considers himself such a device still limited (see. The manufacturer's instructions). But I have not yet measured the Energievebrauch itself.
If a server rack is present, a fine thing to have a lot of space in the home LAN.
