First Deployment of XCache for Workflow and Efficiency Optimizations on Opportunistic HPC Resources in Germany

The future German HEP computing strategy will partially rely on national scientific HPC centers for providing the CPU pledges to the WLCG. The pilot phase for this endeavor is starting in 2025 from which on the share provided by HPC resources will gradually increase. To make this courageous step a success, it is essential that the integrated HPC sites can be utilized just as reliable and efficient for HEP workflows as the traditional, dedicated Grid sites. Motivated by I/O limitations observed at HoreKa, the scientific HPC cluster at KIT, the integration was optimized and an XRootD-based approach for data access bottleneck mitigation was developed and deployed, resulting in a comparable performance of the cluster. This is an important result supporting the future HEP computing strategy in Germany and shows that national scientific HPC centers are capable of delivering the performance and reliability required to be used for providing pledges to the WLCG. Moreover, the findings underline the potential of integrating HPC clusters into the Grid, paving the way for a scalable and sustainable computing infrastructure in the HL-LHC era.