CMS Space Monitoring

During the first LHC run, CMS saturated one hundred petabytes of storage resources with data. Storage accounting and monitoring help to meet the challenges of storage management, such as efficient space utilization, fair share between users and groups, and further resource planning.We present newly developed CMS space monitoring system based on the storage dumps produced at the sites. Storage contents information is aggregated and uploaded to the central database. Web based data service is provided to retrieve the information for a given time interval and a range of sites, so it can be further aggregated and presented in the desired format.The system has been designed based on the analysis of CMS monitoring requirements and experiences of the other LHC experiments. In this paper, we demonstrate how the existing software components of the CMS data placement system PhEDEx have been re-used, reducing dramatically the development effort.