mergerfs combines all those drives/mounts/etc into one. so if you have e.g. “Movies” folders on two drives, the new one has one “Movies” folder with the combined contents of those two drives. when writing to this array, the files are stored where there’s (more) space. so searching stuff recursively is simple.

needless to say, there is no redundancy so if a drive dies, its conent is gone from the array.

Check out git-annex: https://git-annex.branchable.com/

It’s super cool if you know git. It lets you track where your files are without having them all in the same place. You could have a bunch of disconnected hard disks, and git-annex will remember where you put your stuff.

You can also set a minimum number of copies and it will only let you delete stuff from one place when it’s sure there are sufficient copies elsewhere.

I do not recommend using the assistant (edit: nor the webapp) if you’re planning on ever reviewing the repo’s history. It generated a bajillion automatic commits that drown out any handwritten commit messages.