EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH European Laboratory for Particle Physics Online Performance Monitoring of the Third ALICE Data Challenge (ADC III)

AbstractThe ALICE data acquisition system has been designed for a maximum band-width of 2.5 GB/s for event building and of 1.25 GB/s for mass storage. Inorder to attain a gradual integration of the overall computing infrastructure,the present hardware components and software prototypes are tested duringregular ALICE data challenges.The third one (ADC III) took place fromJanuary to March 2001 as a joint effort between the ALICE online/offlineteam and the CERN IT division.The main goal of this data challenge wasto achieve a stable 300 MB/s throughput in the event building network anda 100 MB/s throughput to CASTOR over period of a few days.Performance monitoring was another goal of this exercise, where a proto-type ( dateStat ) was developed to collect and display statistics.In this paperwe will introduce this online monitoring system and report on some of theobtained results.It is structured in three parts: (1) An overview will be givenon the testbed hardware, the software running on it, and the data flow.(2)The architecture of the monitoring system will be described, which consistsof a set of C programs, Perl/gnuplot/CGI scripts, and a MySQL database.It allows to measure individual/aggregate data rates, collected data volumes,and CPU loads.All these values can be visualized on web pages both on arun-by-run and global basis.(3) Various plots will be shown to illustrate theusefulness of this online monitoring system and to document the outcome ofthe ADC III.Finally, some ideas will be pointed out how to advance