Speakers
Description
In preparation for Run-4 and the HL-LHC era, WLCG has initiated the redesign of its XRootD monitoring to provide a coherent and scalable view of data-access activity across distributed sites and experiments. Developed in close collaboration with CMS, the new architecture aims to serve both WLCG-level needs for global observability (such as assessing traffic patterns and validating large-scale data challenges) and CMS operational needs for fine-grained visibility into data-access performance and failure modes. At present, only ALICE provides validated XRootD monitoring by using experiment-specific site-level components. While CERN could theoretically aggregate all data centrally, doing so would require operating and coordinating multiple collectors at scale. In practice, the centrally received streams from other experiments remain incomplete and unverified, underscoring that a central-only model is operationally complex and fragile. Assigning lightweight validation responsibilities to sites offers a more scalable and reliable approach. Building on a systematic assessment of existing deployments, the proposed framework introduces standardised message schemas, resilient transport and buffering semantics, and a clearer separation of responsibilities between site-level and central services. This contribution presents the design, early validation results, and the roadmap towards a unified WLCG–CMS XRootD monitoring infrastructure ready for HL-LHC operations.