CS3 (Cloud Services for Synchronization and Sharing) is a new and growing community, which was initiated at the kick-off event in 2014 at CERN. Over the past few years CS3 workshops have become a point of excellence for cloud storage services and featured four editions hosted across Europe: CERN, ETH Zurich, SURFSara Amsterdam and CYFRONET Krakow. The distinct mark of CS3 is that it grew...