What storage software could I run to have an archive of my personal files (a couple TB of photos) that doesn’t require I keep a full local copy of all the data? I like the idea of a simple and focused tool like Syncthing, but they seem to be angling towards replication.
Is the simple choice to run some S3-like backend and use CLI or other client to append and browse files? I’d love something with fault tolerance that someone can gradually add disks to. If ceph were either less complicated or used less resources I’d want to do that.
It is not that easy to understand what you want, to me it reads like you want something like Nextcloud - i.e. your own little cloud, where you can put all your stuff, and view it through the webbrowser or the nextcloud apps, and also keep selected parts of your stuff in sync with your devices (or automatically upload photos take with your smartphone for example).
Backup of Nextcloud (or whatever you want to use) is a seperate topic. Any incremental backup tool would apply though, so there’s much to choose from. I personally use btrbk which uses Btrfs Send+Receive to push incremental snapshots to an offsite server.