Data preparation for the Compact Muon Solenoid experiment

During the first 3 years of operations at the Large Hadron Collider, the Compact Muon Solenoid detector has collected data across vastly evolving conditions for the center of mass energy, the instantaneous luminosity and the events' pile up. The CMS collaboration has followed this evolution in a continuous way providing high-quality and prompt data reconstruction, necessary for achieving excellent physics performance requested by such high energy physics experiment. The scientific success of CMS came from keeping a constant attention on the key areas: a careful preparation and maintenance of the reconstruction algorithms and core software infrastructure, efficient and robust strategies and algorithms for the calibration and the alignment of the diverse detector elements, up to a continuous and meticulous scrutiny of the data quality and validation of any software infrastructure and detector calibration changes which was deemed necessary. This contribution covers the major development and operational aspects of the CMS offline workflows during data taking experience of 2010-2013, underlying their essential role towards the main physics achievements and discoveries of the CMS experiment during the last years.