What I‘m looking for is a mixture of an overlaying file system like overlayfs or aufs that does a copy-up on read access. Or, from the other side, a service like unison that sync only files that have been requested so far. You could call it a cache, too, but my research didn‘t yield any results.
My use case: I want to prepare updates/relaunches of CMS-driven websites on my local machine. Some of them bring tons of files that clutter my local SSD. I‘d like to mount a remote storage and copy up files on read access - that way I could save both disk space and band width. When I access a remote storage directly I save disk space but waste bandwidth and suffer from latency…
Remote storage might be accessible via SSH or VPN/Samba but I can also mount those to a local folder. So a local-only solution would be fine.
