Use tools like Seafile and Owncloud that keep old versions and offsite. They offer both hosted service and self-installation option. The client notifies you tha

Use tools like Seafile and Owncloud that keep old versions and offsite. They offer both hosted service and self-installation option. The client notifies you that "files X,Y changed" which can make you notice anything untoward is happening to files you are not working with at the moment.