File synchronisation

Have two sites, the main site with the Terminal Server in it and a remote site that has a small file server.

My mind is not getting the easy answer I expect there is to this for some reason so I thought I'd call for help.

What would be the best way to make some files available at the remote site in the event of a failure to the internet connection between the sites or a problem with the terminal server?

We can, I would imagine, use something like synctoy to synchronise the files overnight or every hour or something but is there a way to keep them synchronised live?