Mar 21 – 27, 2009
Europe/Prague timezone

Architecture of the CMS Data Acquisition System

Mar 26, 2009, 8:00 AM


Prague Congress Centre 5. května 65, 140 00 Prague 4, Czech Republic
Board: Thursday 099
poster Online Computing Poster session


Dr Vivian ODell (FNAL)


The CMS event builder assembles events accepted by the first level trigger and makes them available to the high-level trigger. The system needs to handle a maximum input rate of 100 kHz and an aggregated throughput of 100 GBytes/s originating from approximately 500 sources. This paper presents the chosen hardware and software architecture. The system consists of 2 stages: an initial pre-assembly and several independent Readout Builder (RU builder) slices. The RU builder is based on 3 separate services: the buffering of event fragments during the assembly, the event assembly, and the data flow manager. A further component is responsible to handle events accepted by the high-level trigger: the Storage Manager compresses and stores the events on disk at a peak rate of 2 GBytes/s and makes them available for offline processing. In addition, events and data-quality histograms are served to online monitoring clients. We discuss the operational experience from the first months of reading out the complete CMS detector.

Primary author

Dr Vivian ODell (FNAL)

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