Online data handling and storage at the CMS experiment
Name
Online data handling.pdf
Size
5.18 MB
Format
Adobe PDF
Checksum (MD5)
ab79e0f6882430c421f772697f0fdb7c
Author(s)
Darlea, G.-L.
Demiragli, Zeynep
Gomez-Ceballos, Guillelmo
Paus, Christoph M. E.
Sumorok, Konstanty C
Veverka, Jan
Date Issued
December 2015
Journal
Journal of Physics: Conference Series
Publisher
IOP Publishing
Citation
Andre, J-M et al. “Online Data Handling and Storage at the CMS Experiment.” Journal of Physics: Conference Series 664.8 (2015): 082009.
Version
Final published version
Abstract
During the LHC Long Shutdown 1, the CMS Data Acquisition (DAQ) system underwent a partial redesign to replace obsolete network equipment, use more homogeneous switching technologies, and support new detector back-end electronics. The software and hardware infrastructure to provide input, execute the High Level Trigger (HLT) algorithms and deal with output data transport and storage has also been redesigned to be completely file- based. All the metadata needed for bookkeeping are stored in files as well, in the form of small documents using the JSON encoding. The Storage and Transfer System (STS) is responsible for aggregating these files produced by the HLT, storing them temporarily and transferring them to the T0 facility at CERN for subsequent offline processing. The STS merger service aggregates the output files from the HLT from ~62 sources produced with an aggregate rate of ~2GB/s. An estimated bandwidth of 7GB/s in concurrent read/write mode is needed. Furthermore, the STS has to be able to store several days of continuous running, so an estimated of 250TB of total usable disk space is required. In this article we present the various technological and implementation choices of the three components of the STS: the distributed file system, the merger service and the transfer system.
MIT Department
Massachusetts Institute of Technology. Laboratory for Nuclear Science
Terms of Use
Creative Commons Attribution 3.0 Unported license
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1088/1742-6596/664/8/082009
