Abstract

The DAQ system of the CMS experiment at the LHC is upgraded 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 Q(10) filter-unit machines (FUs) running the HLT code. The FUs read the raw data from the file system, select Q(1%) of the events, and write the selected events together with monitoring meta-data 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.

Details

Title
Prototype of a File-Based High-Level Trigger in CMS
Author
Bauer, G 1 ; Bawej, T 2 ; Behrens, U 3 ; Branson, J 4 ; Chaze, O 2 ; Cittolin, S 4 ; Coarasa, J A 2 ; G-L Darlea 1 ; Deldicque, C 2 ; Dobson, M 2 ; Dupont, A 2 ; Erhan, S 5 ; Gigi, D 2 ; Glege, F 2 ; Gomez-Ceballos, G 1 ; Gomez-Reino, R 2 ; Hartl, C 2 ; Hegeman, J 2 ; Holzner, A 4 ; Masetti, L 2 ; Meijers, F 2 ; Meschi, E 2 ; Mommsen, R K 6 ; Morovic, S 7 ; Nunez-Barranco-Fernandez, C 2 ; O'Dell, V 6 ; Orsini, L 2 ; Ozga, W 2 ; Paus, C 1 ; Petrucci, A 2 ; Pieri, M 4 ; Racz, A 2 ; Raginel, O 1 ; Sakulin, H 2 ; Sani, M 4 ; Schwick, C 2 ; Spataru, Ac 2 ; Stieger, B 2 ; Sumorok, K 1 ; Veverka, J 1 ; Wakefiled, C C 2 ; Zejdl, P 2 

 Massachusetts Institute of Technology, Cambridge, Massachusetts, USA 
 CERN, Geneva, Switzerland 
 DESY, Hamburg, Germany 
 University of California, San Diego, California, USA 
 University of California, Los Angeles, California, USA 
 FNAL, Chicago, Illinois, USA 
 CERN, Geneva, Switzerland; Also at Institute Rudjer Boskovic, Zagreb, Croatia 
Publication year
2014
Publication date
Jun 2014
Publisher
IOP Publishing
ISSN
17426588
e-ISSN
17426596
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2576664291
Copyright
© 2014. This work is published under http://creativecommons.org/licenses/by/3.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.