We will need a separate state file to store info on what's happening in order to support extracting status from a running instance. This should be separate from the last mirror time file, as the information in the state file will be non-critical and may be re-written during a run (which would break a lock).

Will also need a defined place to persistently store info like the last N transfer logs. That's sorely needed for me to understand the internals of transfer list extraction without having to catch a live transfer.

Both should of course be configurable and all of the functionality should be disabled by default.