I've been struggling with 1) for years. My current attempt is to exploit ZFS snapshot shipping, since modern ZFS ports are available for both mac and linux (an

I've been struggling with 1) for years. My current attempt is to exploit ZFS snapshot shipping, since modern ZFS ports are available for both mac and linux (and apparently one for windows is on the way). Unlike rsync, ZFS always knows what's changed since the last snapshot, so there's no directory scanning. Unlike inotify, there is (seemingly) no(?) risk of dropped events, which I've experienced with tools like watchman. My ZFS solution still needs prompting event to start the snapshot, but it no longer needs to be told _what_ changed. Critically the sync flows in one direction. This is a deal breaker for applications that need to communicate file changes back out to the host, but that hasn't been an issue in my use cases. Unlike NFS, it also means we must (and can) relax the strong consistency model, and so using the filesystem is not so latency bound. This becomes important if the virtual machine is not running locally..