LHCb: Handling online information in the LHCb experiment

The LHCb experiment is a complex particle physics detector, large amount of information is needed for its run time configuration, control and monitoring. All these data are stored in the three main logical databases of the online system: configuration database, archiving database and conditions database. The configuration database contains information needed by the online hardware and software components, like for example the electronics boards, high voltage and low voltage power supplies and trigger algorithms, to be configured, according to the partitioning mode (which components are needed) and running mode(which data are being produced: physics, cosmic, test, etc.). The archiving database contains all data read from hardware used for the monitoring and debugging of the experiment, like for example temperature readings. The third online database, the conditions database, contains a subset of the monitoring data, read from hardware, that are needed for physics processing and also some configuration data, like for example, the trigger settings. The interfaces to these databases have been developed as a component of the LHCb control framework and they are based on a SCADA (Supervisory Control and Data Acquisition) system called PVSSII. The implemented solution will be explained in detail, from the motivation of all choices, in term of design and implementation, to the integration of the databases in the online system.