The CMS experiment data acquisition (DAQ) collects data for events accepted by the Level-1 trigger from the different detector systems and assembles them in an event builder prior to making them available for further selection in the High Level Trigger, and finally storing the selected ones for offline analysis. In addition to the central DAQ providing global acquisition functionality, several separate, so-called “MiniDAQ” setups allow operating independent data acquisition runs using an arbitrary subset of the CMS subdetectors.
During Run 2 of the LHC, MiniDAQ setups were running their event builder and high level trigger applications on dedicated resources, separate from those used for the central DAQ. This cleanly separated MiniDAQ setups from the central DAQ system, but also meant limited throughput and a fixed number of possible MiniDAQ setups. In Run 3, MiniDAQ-3 setups share production resources with the new central DAQ system, allowing each setup to operate at the maximum Level-1 rate thanks to the reuse of the resources and network bandwidth.
The configuration management tool defines the assignment of shared resources to subdetectors and provides functionality to evolve it, for example when hardware becomes unavailable, minimizing changes to unaffected parts of the system, in such a way as to not disturb ongoing independent runs. A system has been implemented to automatically synchronize MiniDAQ configurations to that of the central DAQ in order to minimize required operator and expert interventions in case of re-assignment of resources. The configuration management tool further provides expert features needed during the commissioning of the new DAQ system, to enable for example performance tests of most of the resources, concurrently to providing MiniDAQ for the commissioning of selected subdetectors.
We report on the new configuration management features and on the first year of operational experience with the new MiniDAQ-3 system.
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