the idea behind VFS is you have data stored on the server and only a subset exist on the client.. files from the server are visible on the client but only download on demand. This is how it works.
If your goal is to upload more data than your client can handle there are multiple options:
- upload directly to the server (using web, webdav etc) and “sync” using VFS
- upload through the client but split into batches so the client uploads the files to the server in background and “dehydrate” files freeing up space for the next batch
I recommend you to go through 101: Self-hosting information for beginners to understand what you need to know as an admin to avoid frustration and data loss