Thanks a lot for explaining. Maybe I can make good use of it. For Mac, I'll try to make a DIY https://en.wikipedia.org/wiki/Fusion_Drive where the large/slow part is a 20 TB network volume. At most ~50 GB would have to be cached when in use (totally pruneable before caching some other portion). There's a lot of automagic with https://en.wikipedia.org/wiki/Core_Storage , but provided it actually works, it's ok if I have to trigger pruning manually or something like that. As long as there's some indicator that it needs to be done. I'll try CloudDrive when I'm on Windows and maybe find uses for it there. It'll be a great reference at any rate.