Dr Vincent Garonne (CERN)
The DQ2 Distributed Data Management system is the system developed and used by ATLAS for handling very large datasets. It encompasses data bookkeeping, managing of largescale production transfers as well as endusers data access requests. In this paper, we will describe the design and implementation of the DQ2 accounting service. It collects different data usage informations in order to show and compare them from the experiment and application perspective. Today, the DQ2 data volume represents more than 8 petabytes, ~70 million file and 500 k dataset replicas, distributed in more than 500 grid storage endpoints.