14-18 October 2013
Amsterdam, Beurs van Berlage
Europe/Amsterdam timezone

Prototype of a File-Based High-Level Trigger in CMS

15 Oct 2013, 16:25
Verwey Kamer (Amsterdam, Beurs van Berlage)

Verwey Kamer

Amsterdam, Beurs van Berlage

Oral presentation to parallel session Data acquisition, trigger and controls Data Acquisition, Trigger and Controls


Dr Remi Mommsen


The DAQ system of the CMS experiment at the LHC is redesigned during the accelerator shutdown in 2013/14. To reduce the interdependency of the DAQ system and the high-level trigger (HLT), we investigate the feasibility of using a file-system-based HLT. Events of ~1 MB size are built at the level-1 trigger rate of 100 kHz. The events are assembled by ~50 builder units (BUs). Each BU writes the raw events at ~2GB/s to a local file system shared with O(10) filter-unit machines (FUs) running the HLT code. The FUs read the raw data from the file system, select O(10^-3) of the events, and write the selected events together with monitoring metadata back to a disk. This data is then aggregated over several steps and made available for offline reconstruction and online monitoring. We present the challenges, technical choices, and performance figures from the prototyping phase. In addition, the steps to the final system implementation will be discussed.

Primary author


Andre Georg Holzner (Univ. of California San Diego (US)) Andrea Petrucci (CERN) Andrei Cristian Spataru (CERN) Dr Attila Racz (CERN) Aymeric Arnaud Dupont (CERN) Carlos Nunez Barranco Fernandez (CERN) Christian Deldicque (CERN) Christian Hartl (CERN) Christoph Paus (Massachusetts Inst. of Technology (US)) Christoph Schwick (CERN) Christopher Colin Wakefield (Staffordshire University (GB)) Dominique Gigi (CERN) Emilio Meschi (CERN) Fabian Stoeckli (Massachusetts Inst. of Technology (US)) Frank Glege (CERN) Frans Meijers (CERN) Gerry Bauer (Massachusetts Inst. of Technology (US)) Dr Giovanni Polese (University of Wisconsin (US)) Hannes Sakulin (CERN) James Gordon Branson (Univ. of California San Diego (US)) Dr Jose Antonio Coarasa Perez (CERN) Konstanty Sumorok (Massachusetts Inst. of Technology (US)) Lorenzo Masetti (CERN) Luciano Orsini (CERN) Dr Marc Dobson (CERN) Marco Pieri (Univ. of California San Diego (US)) Matteo Sani (Univ. of California San Diego (US)) Olivier Chaze (CERN) Olivier Raginel (Massachusetts Inst. of Technology (US)) Petr Zejdl (CERN) Robert Gomez-Reino Garrido (CERN) Samim Erhan (Univ. of California Los Angeles (US)) Sergio Cittolin (Univ. of California San Diego (US)) Srecko Morovic (Institute Rudjer Boskovic (HR)) Ulf Behrens (Deutsches Elektronen-Synchrotron (DE)) Vivian O'Dell (Fermi National Accelerator Laboratory (FNAL)) Wojciech Andrzej Ozga (AGH University of Science and Technology (PL))

Presentation Materials