Graeme Andrew Stewart (CERN)Dr Stephane Jezequel (LAPP)
This paper will summarize operational experience and improvements in ATLAS computing infrastructure during 2010 and 2011. ATLAS has had 2 periods of data taking, with many more events recorded in 2011 than in 2010. It ran 3 major reprocessing campaigns. The activity in 2011 was similar to that in 2010, but scalability issues had to be adressed due to the increase in luminosity and trigger rate. Based on improved monitoring of ATLAS Grid computing, the evolution of computing activities (data/group production, their distribution and grid analysis) over time will be presented. The major bottlenecks and the implemented solutions will be described. The main changes in the implementation of the computing model that will be shown are: the optimisation of data distribution over the Grid, according to effective transfer rate and site readiness for analysis; the relaxation of the cloud model, for data distribution and data processing; software installation migration to cvmfs; changing database access to a Frontier/squid infrastructure.
Collaboration Atlas (Atlas)