M. Schulz (CERN)
LCG2 is a large scale production grid formed by more than 40 worldwide distributed sites. The aggregated number of CPUs exceeds 3000 several MSS systems are integrated in the system. Almost all sites form an independent administrative domain. On most of the larger sites the local computing resources have been integrated into the grid. The system has been used for large scale production by LHC experiments for several month. During the operation the software went through several versions and had to be upgraded including non backward compatible upgrades. We report on the experience gained setting up the service, integrating sites and operating it under the load of the production.