A wide range of detector commissioning, calibration and data analysis tasks is carried out by CMS using dedicated storage resources available at the CMS CERN Tier-2 centre. Relying on the functionalities of the EOS disk-only storage technology, the optimal exploitation of the CMS user group resources has required the introduction of policies for data access management, data protection, cleanup campaigns based on access pattern, and long term tape archival. The resource management has been organised around the definition of working groups and the delegation to an identified responsible of each group composition. In this paper we illustrate the user group storage management, and the development and operational experience at the CMS CERN Tier-2 centre in the 2012-2015 period.