Speaker
Description
The CMS Tier-0 system is responsible for the prompt processing and distribution of data collected by the CMS experiment. During Run 3, the LHC delivered almost twice the luminosity of Run 2, while the CMS physics program intensified and diversified year by year, resulting in an average data rate of up to 12 GB/s and a total RAW data volume of 110 PB so far. Higher load places increased pressure on the Tier-0 system, making changes necessary to cope with the higher throughput. The sustained high data rates require increased use of CPU resources up to 150 k cores, using the worldwide computing resources available to CMS in order to promptly reconstruct the data. Furthermore, the higher data volumes require increased utilization of disk and tape resources, as well as improvements to the workload management system. In this work, we demonstrate the CMS Tier-0 performance for proton-proton, light-ion, and heavy-ion collisions during Run 3. We show how Tier-0 scaled up to cope with increased pressure by utilizing record-breaking CPU resources, expanding its disk and tape storage capacities, and adapting its workload management system accordingly.