ATLAS Online Data Quality Monitoring

Every minute of an ATLAS data taking session, the monitoring framework serves several thousands of physics events to the monitoring data analysis applications and handles millions of histogram updates coming from many di erent applications. This framework also executes over forty thousand advanced data quality checks for a subset of those histograms and displays those histograms together with the results of all those checks on several dozens of monitors installed in main and satellite ATLAS control rooms. The Data Quality Monitoring Display (DQMD) is the visualization tool for the automatic data quality as- sessment. It is the interface through which the shift crew and the experts can validate the quality of the data being recorded or processed, be warned of problems related to data quality, and identify the origin of such prob- lems. This tool allows great exibility for visualization of histograms, with an overlay of reference histograms when applicable, con gurations used for automatic checking of those histograms, and the results. The display con guration is stored in a database, that can be easily created and edited with the Data Quality Monitoring Con gurator (DQMC) tool. The rst months of collisions data taking turned into a very successful experience for the monitoring framework and translated into several improvements to easy usability and ecient information transfer. A description of the design and implementation of th e DQMD and DQMC will be presented, as well as the performance of the monitoring framework during the rst ATLAS run and the recent upgrades concerning alarm handling and parameters finding.