The U.S. ATLAS Tier-2 Meeting agenda centered on moving the Computing Facilities from development and deployment into stable and continuous operation. The goal is to enable ATLAS Physics Analysis in time for U.S. physicists to participate in the worldwide effort in a competitive manner.

Meeting topics included choices and scalability of site architecture, in particular scalability of middleware components which we are using to access the available distributed resources Still on the critical path are data storage and transfer services.

A smooth transition from enthusiastic development and deployment to stable operation is the next natural step. We expect both the OSG and the ATLAS software and services to continue to evolve in 2007, and reach a point of stability by the time LHC data taking starts. Stability is likely to be more important than performance.

Since the Tier-2 centers will soon become a precious resource for physics analysis, in addition to Monte Carlo production, we need to implement the full ATLAS Computing Model on each of the sites that will support ATLAS data analysis. In particular, we need to develop ways to host and handle the great diversity of datasets that will be arriving.

To ensure effective collaboration among all people involved in this effort, from the Tier-1 down to the Tier-3 centers, we are in the process of defining the necessary steps, roles and schedule, aligned with the ATLAS milestones. Following each installation and configuration step, a validation step will follow in order to certify a site's readiness.