2.1 Introduction to the Basics of CMS Offline Computing

This chapter introduces you to the CMS computing environment and to CMSSW, the CMS software framework used to perform analysis using collision data and MC datasamples.

The CMS Computing Model section describes how computing centres available to CMS around the world are distributed and configured in a tiered architecture that functions as a single coherent system. It also describes how detector data and MC data travel through the tiers, and how data are distributed, stored, and accessed.

CMSSW consists of over a thousand subpackages which have been created to provide an extensive toolkit for users to carry out analyses of data and perform other software-related tasks with only a small contribution of code by themselves. The CMSSW Application Framework section describes:

• the modular architecture of the CMSSW framework
• what comprises an Event
• how data are uniquely identified in an Event
• how Event data are processed
• the basics of provenance tracking.

Review status

Responsible: SudhirMalik
Last reviewed by: KatiLassilaPerini - 02 Feb 2011