The ATLAS computing model

Abstract

The ATLAS Offline Computing Model is described. The main emphasis is on the steady state, when normal running is established. The data flow from the output of the ATLAS trigger system through processing and analysis stages is analysed, in order to estimate the computing resources, in terms of CPU power, disk and tape storage and network bandwidth, which will be necessary to guarantee speedy access to ATLAS data to all members of the Collaboration. Data Challenges and the commissioning runs are used to prototype the Computing Model and test the infrastructure before the start of LHC operation. The initial planning for the early stages of data-taking is also presented. In this phase, a greater degree of access to the unprocessed or partially processed raw data is envisaged.