File-based data flow in the CMS Filter Farm Andre, J-M; Andronidis, A; Bawej, T ...
Journal of physics. Conference series,
12/2015, Letnik:
664, Številka:
8
Journal Article
Recenzirano
Odprti dostop
During the LHC Long Shutdown 1, the CMS Data Acquisition system underwent a partial redesign to replace obsolete network equipment, use more homogeneous switching technologies, and prepare the ground ...for future upgrades of the detector front-ends. 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. This approach provides additional decoupling between the HLT algorithms and the input and output data flow. All the metadata needed for bookkeeping of the data flow and the HLT process lifetimes are also generated in the form of small "documents" using the JSON encoding, by either services in the flow of the HLT execution (for rates etc.) or watchdog processes. These "files" can remain memory-resident or be written to disk if they are to be used in another part of the system (e.g. for aggregation of output data). We discuss how this redesign improves the robustness and flexibility of the CMS DAQ and the performance of the system currently being commissioned for the LHC Run 2.
The data-acquisition system of the CMS experiment at the LHC performs the read-out and assembly of events accepted by the first level hardware trigger. Assembled events are made available to the ...high-level trigger which selects interesting events for offline storage and analysis. The system is designed to handle a maximum input rate of 100 kHz and an aggregated throughput of 100GB/s originating from approximately 500 sources. An overview of the architecture and design of the hardware and software of the DAQ system is given. We discuss the performance and operational experience from the first months of LHC physics data taking.
The CMS data acquisition system software Bauer, G; Behrens, U; Biery, K ...
Journal of physics. Conference series,
04/2010, Letnik:
219, Številka:
2
Journal Article
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The CMS data acquisition system is made of two major subsystems: event building and event filter. The presented paper describes the architecture and design of the software that processes the data ...flow in the currently operating experiment. The central DAQ system relies on industry standard networks and processing equipment. Adopting a single software infrastructure in all subsystems of the experiment imposes, however, a number of different requirements. High efficiency and configuration flexibility are among the most important ones. The XDAQ software infrastructure has matured over an eight years development and testing period and has shown to be able to cope well with the requirements of the CMS experiment.
The CMS experiment at the LHC features a two-level trigger system. Events accepted by the first level trigger, at a maximum rate of 100 kHz, are read out by the Data Acquisition system (DAQ), and ...subsequently assembled in memory in a farm of computers running a software high-level trigger (HLT), which selects interesting events for offline storage and analysis at a rate of order few hundred Hz. The HLT algorithms consist of sequences of offline-style reconstruction and filtering modules, executed on a farm of 0(10000) CPU cores built from commodity hardware. Experience from the operation of the HLT system in the collider run 2010/2011 is reported. The current architecture of the CMS HLT, its integration with the CMS reconstruction framework and the CMS DAQ, are discussed in the light of future development. The possible short- and medium-term evolution of the HLT software infrastructure to support extensions of the HLT computing power, and to address remaining performance and maintenance issues, are discussed.
The error and alarm system for the data acquisition of the Compact Muon Solenoid (CMS) at CERN was successfully used for the physics runs at Large Hadron Collider (LHC) during first three years of ...activities. Error and alarm processing entails the notification, collection, storing and visualization of all exceptional conditions occurring in the highly distributed CMS online system using a uniform scheme. Alerts and reports are shown on-line by web application facilities that map them to graphical models of the system as defined by the user. A persistency service keeps a history of all exceptions occurred, allowing subsequent retrieval of user defined time windows of events for later playback or analysis. This paper describes the architecture and the technologies used and deals with operational aspects during the first years of LHC operation. In particular we focus on performance, stability, and integration with the CMS sub-detectors.
The data-acquisition (DAQ) system of the CMS experiment at the LHC performs the read-out and assembly of events accepted by the first level hardware trigger. Assembled events are made available to ...the high-level trigger (HLT), which selects interesting events for offline storage and analysis. The system is designed to handle a maximum input rate of 100 kHz and an aggregated throughput of 100 GB/s originating from approximately 500 sources and 10^8 electronic channels. An overview of the architecture and design of the hardware and software of the DAQ system is given. We report on the performance and operational experience of the DAQ and its Run Control System in the first two years of collider runs of the LHC, both in proton-proton and Pb-Pb collisions. We present an analysis of the current performance, its limitations, and the most common failure modes and discuss the ongoing evolution of the HLT capability needed to match the luminosity ramp-up of the LHC.
The CMS experiment at the LHC features over 2'500 devices that need constant monitoring in order to ensure proper data taking. The monitoring solution has been migrated from Nagios to Icinga, with ...several useful plugins. The motivations behind the migration and the selection of the plugins are discussed.
Upgrade of the CMS Event Builder Bauer, G; Behrens, U; Bowen, M ...
Journal of physics. Conference series,
01/2012, Letnik:
396, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The Data Acquisition system of the Compact Muon Solenoid experiment at CERN assembles events at a rate of 100 kHz, transporting event data at an aggregate throughput of 100 GB/s. By the time the LHC ...restarts after the 2013/14 shut-down, the current computing and networking infrastructure will have reached the end of their lifetime. This paper presents design studies for an upgrade of the CMS event builder based on advanced networking technologies such as 10/40 Gb/s Ethernet and Infiniband. The results of performance measurements with small-scale test setups are shown.
The Compact Muon Solenoid (CMS) experiment at CERN is a multi-purpose experiment designed to exploit the physics of proton-proton collisions at the Large Hadron Collider collision energy (14TeV at ...centre of mass) over the full range of expected luminosities (up to 1034cm−2s−1). The CMS detector control system (DCS) ensures a safe, correct and efficient operation of the detector so that high quality physics data can be recorded. The system is also required to operate the detector with a small crew of experts who can take care of the maintenance of its software and hardware infrastructure. The subsystems size sum up to more than a million parameters that need to be supervised by the DCS. A cluster of roughly 100 servers is used to provide the required processing resources. A scalable approach has been chosen factorizing the DCS system as much as possible. CMS DCS has made clear a division between its computing resources and functionality by creating a computing framework allowing plugging in of functional components. DCS components are developed by the subsystems expert groups while the computing infrastructure is developed centrally. To ensure the correct operation of the detector, DCS organizes the communication between the accelerator and the experiment systems making sure that the detector is in a safe state during hazardous situations and is fully operational when stable conditions are present. This paper describes the current status of the CMS DCS focusing on operational aspects and the role of DCS in this communication.
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