When you install Revit Server, you can store the central model of a workshared project on a server to improve performance for team members working across a WAN.
When upgrading to Revit 2011 Subscription Advantage Pack, Revit 2012, Revit 2013, or Revit 2014, you can migrate from the file-based system for storing the central model to the server-based system. For instructions, see Implementing Server-Based Worksharing from File-Based Worksharing.