I'm still waiting for an overlayfs that does read caching on the overlay without the need to format the backing storage.
This is what bcachefs is based on.
> You'll need make-bcache from the bcache-tools repository. Both the cache device and backing device must be formatted before use.
So, it's far from overlayfs. I could accept formatting the cache device, but not the backing storage.
I got partway thru setting up a script to copy recently accessed files from the HDD to the read-prioritized SSD.
My LLMs load up way faster, and I still have a source of truth volume in the huge HDD. It’s not something I’d use professionally though, way too janky.