Hi Eloise,<br />
<br />
I have an older model of the Synology 4-bay NAS (CS-407e), and I have an external drive connected to one of the USB ports on the device.<br />
<br />
I have an automated, incremental backup scheduled to the USB drive. I would be surprised if that feature is not included in this device - even though it is a "slim" version.<br />
<br />
You are, of course, completely correct in saying "RAID is not backup". I learnt that one the hard way