The WLCG Data Challenge

During Run-3 the Large Hadron Collider (LHC) experiments are transferring up to 10PB of data daily across the Worldwide LHC Computing Grid (WLCG) sites. However, following the transition from Run-3 to Run- 4, data volumes are expected to increase tenfold. The WLCG Data Challenge aims to address this significant scaling challenge through a series of rigorous test events. The primary objective of the 2024 Data Challenge (DC24) was to achieve 25% of the anticipated bulk transfer rate required for Run-4. Six experiments participated: the LHC experiments—ATLAS, CMS, LHCb, and ALICE—as well as Belle II and DUNE. These experiments utilize many of the same networks, sites and data management tools. Additionally, DC24 aimed to test new technologies such as token-based authorization and advanced network monitoring tools. The direct benefits of DC24 included identifying bottlenecks within the centralized data management systems of each experiment, gaining experience with significantly higher data transfer rates, and fostering significant collaboration among experiments and stakeholders. These stakeholders encompassed site administrators, storage technology providers, network experts, and middleware tool developers, all contributing to the preparedness for the demands of Run-4.