The ATLAS computing model and distributed computing evolution

Despite only a brief availability of beam-related data, the typical usage patterns and operational requirements of the ATLAS computing model have been exercised, and the model as originally constructed remains remarkably unchanged. Resource requirements have been revised, and cosmic ray running has exercised much of the model in both duration and volume. The operational model has been adapted in several ways to increase performance and meet the asdelivered functionality of the available middleware. There are also changes reflecting the emerging roles of the different data formats. The model continues to evolve with a heightened focus on end-user performance, the key tools developed in the operational system are outlined, with an emphasis on those under recent development.