DAQExpert the service to increase CMS data-taking efficiency

Abstract

The Data Acquisition (DAQ) system of the Compact Muon Solenoid (CMS) experiment at the LHC is a complex system responsible for the data readout, event building and recording of accepted events. Its proper functioning plays a critical role in the data-taking efficiency of the CMS experiment. In order to ensure high availability and recover promptly in the event of hardware or software failure of the subsystems, an expert system, the DAQ Expert, has been developed. It aims at improving the data taking efficiency, reducing the human error in the operations and minimising the on-call expert demand. Introduced in the beginning of 2017, it assists the shift crew and the system experts in recovering from operational faults, streamlining the post mortem analysis and, at the end of Run 2, triggering fully automatic recovery without human intervention. DAQ Expert analyses the real-time monitoring data originating from the DAQ components and the high-level trigger updated every few seconds. It pinpoints data flow problems, and recovers them automatically or after given operator approval. We analyse the CMS downtime in the 2018 run focusing on what was improved with the introduction of automated recovery; present challenges and design of encoding the expert knowledge into automated recovery jobs. Furthermore, we demonstrate the web-based, ReactJS interfaces that ensure an effective cooperation between the human operators in the control room and the automated recovery system. We report on the operational experience with automated recovery.

Development of the CMS detector for the CERN LHC Run 3

“…The monitoring clients typically display instant data with a latency of a few seconds and can also be used to browse historic data to facilitate post-mortem analysis. The Java-based DAQ expert tool [283][284][285] detects all common data-taking problems by evaluating rules encapsulated in logic modules using snapshots of monitoring data. This helps the shift-crew with the sometimes difficult task of pin-pointing the cause of data-flow problems.…”

Data Acquisition System for the COMPASS++/ AMBER Experiment

“…The FPGA-based system requires only a fast reset signal to recover in contrast to the software-based systems which have to reload and reinitialize the full software stack. The reliability translates into the uptime of the system: the data acquisition systems with software-based event builder showed an uptime of 91.7 % (ATLAS 2016 [6]) and 95.87 % (CMS 2018 [7]) while the COMPASS data acquisition system with fully FPGA-based event builder showed an uptime of 99.6 % [8].…”