For the longest time my backup strategy consisted of two parts: Personal files are automatically synced with OneDrive on my PC and laptop. My NAS mirrors some of that data and occasionally exports it to an external HDD. And then every few months I rotate that external HDD with a different one and store the other at my parents. So for most of my data I did actually have 3 copies on 2 different media types with 1 (or 2 even) stored off-site. But when I upgraded my NAS to 4 TB drives I couldn’t backup all the data anymore...