- Synology NAS is accessible on LAN & phones sync photos when at home
- Nightly rsync from internal NAS storage to 1 external (non-raid) hard drive
The nightly rsync does not delete files, so the external hard drive is pretty close to an off-site backup even though it's still attached. The only better thing I've thought of doing is mounting it ro after backups + re-mounting before backups.
At the end of the day we get 3 copies of data: the photo on your phone, the photo on the shared NAS, and the photo on an external hard drive that spends 99% of its life spun down.