Speaker
Description
The ATLAS detector at the Large Hadron Collider processes 40 million proton-proton collision events per second. The Readout system is a central component of the ATLAS data-acquisition infrastructure, interfacing with the detector electronics. For the HL-LHC, starting in 2030, the Readout system will receive data from more than 15,000 optical links, each operating at 1 MHz, corresponding to an aggregated throughput of 5 TB/s. The system will ingest and de-serialise data using custom FPGA-based PCIe cards (FELIX); process and aggregate data with the Data Handler software; and distribute data via a 400 Gb/s network. In addition, the Readout infrastructure will deliver timing and trigger information, configuration and control commands, and monitoring data.
In the original design, FELIX and the Data Handler were hosted on separate server pools, interconnected by a dedicated network and requiring about 1,000 computing units. Following a requirements review, lessons learned during the ongoing data-taking period, and the recent computing hardware capabilities, the design was updated in 2025 to integrate both components onto a single server platform. The new architecture provides a more reliable, serviceable, and compact system, requiring only about 300 servers with minimal feature loss.
This talk presents the ATLAS HL-LHC Readout architecture, highlighting requirements and challenges. Operational and technological aspects enabling the design update will be discussed, together with the performance of the updated system. Lessons learned in executing demanding I/O workloads on modern computer systems will also be presented, including software optimisations, application layout, and operating system configuration.
| Minioral | Yes |
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| IEEE Member | No |
| Are you a student? | No |