Ooh, I'd love that. Or native steam functionality for the same. I never install games onto my SSD for that reason, so I'm at the mercy of whatever windows naturally does in that space. (Possibly nothing, as I don't remember manually configuring a SSD cache file on this computer, and last I checked that was required).

i recommend primocache on Windows

seconded. Primocache is wonderful, and doesn't suffer from the glaring issue using the powershell hack of Windows Storage Spaces [1]. You can set this up, with proper powershell scripts/commands, but Xbox games won't install to a Storage Space. It boggled my mind when I finally tracked this down.

Primo Cache [2] has one disadvantage over storage spaces - the SSD cache space is dedicated as Cache, and does not add to the total space of the drive. 1TB SSD + 4TB hdd = 4TB available, vs storage spaces which will give you 5TB. This minor (to me) downside is outweighed by the fact it works for everything. It shows up as a normal drive, not a virtual disk, and it just works. I recommend it highly for anyone who has limited SSD space.

1: https://github.com/freemansoft/win10-storage-spaces 2: https://www.romexsoftware.com/en-us/primo-cache/

On Linux you have bcache and flashcache, but they work on the block layer and not file layer.

And I believe the work-in-progress bcachefs also supports this use case.