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LHCb Online

LHCb Online. & the Conditions DB. Online Usage of CondDB. Two completely independent users: The Experiment Control System Writes Online Conditions in the DB The Event Filter Farm Algorithms Need Conditions for their processing/filtering tasks. LHCb Online.

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LHCb Online

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  1. LHCb Online & the Conditions DB

  2. Online Usage of CondDB • Two completely independent users: • The Experiment Control System • Writes Online Conditions in the DB • The Event Filter Farm Algorithms • Need Conditions for their processing/filtering tasks

  3. LHCb Online DCS Devices (HV, LV, GAS, Temperatures, etc.) Detector Channels Trigger Front End Electronics Experiment Control System Readout Network Processing/Filtering Farm Storage DAQ External Systems(LHC,Technical Services,Safety,etc)

  4. Experimental Equipment Data Handling Architecture Conf. DB ... ... PVSS PVSS PVSS PVSS PVSS Arch. PVSS PVSS PVSS PVSS ... ... . . Cond. To Offline To Offline DB

  5. Conditions DB • From the Control System point of view: • Only output • Only one interface: • from the ECS i.e. PVSS • Clients (offline algorithms) determine: • Data organization • Data format: XML (?) • Data update rate • Data could be stored in the Cond DB only if it changed by more than X or every hour • independently of the PVSS read-out rate.

  6. Online Conditions Sources • DCS • High Voltages, temperatures, pressures, etc. • DAQ & Trigger • Pedestals, thresholds, zero suppression parameters, gains, etc. • DAQ & Trigger setup parameters • EFF (Event Filter Farm) • Pedestals, Thresholds, Gain Calibration, Alignment Constants, etc. • External Systems • Accelerator data: energy, luminosity, average bunch currents, etc.

  7. Conditions Data Types • Raw DataValues read directly from hardware (ex.: HV readings, Temperatures, raw alignment data, etc.) • No Versions, no Tags (not sure yet…) • Processed DataResults of calculations done on raw data (ex.: calibration constants, alignment, etc.) • Automatic Versioning, User Tags

  8. Event Builder Switch SFC SFC SFC CPU CPU CPU . . . CPU CPU CPU . . . . . . . . . CPU CPU CPU Event Filter Farm & CondDB • The Sub Farm Controller (SFC) builds complete events • Sends each event to a free CPU for processing/filtering • A Control PC controls ~2 Sub-farms (< 50 PCs) • ~ 2000 CPUs in total

  9. Event Filter Farm CPUs • Run "Offline" Algorithms Online: • Ex: trigger, reconstruction, calibration, alignment, etc. • Within the Gaudi "Offline" Framework.(has been interfaced to PVSS for Online Monitoring and Control) • Need Conditions data: • The Control PCs will get a snapshot of the CondDB (at the Start of Run) and send it to the CPUs • This snapshot will get an ID stored in the event data to be able to reproduce the algorithm results later • Not clear yet if conditions need updating during a run…

  10. COOL Usage • Both Applications: • ECS writing Conditions for "Offline" • ECS reading conditions for the EFF • Will use the COOL API • We don't mind how COOL is implemented as long as: • The necessary functionality is available (not the case yet) • Its efficient enough • But the API seems to depend on: • RAL, SEAL, POOL, BOOST, etc. • So we'll probably setup a "stand-alone" machine running one or more Cond DB servers (prob. via DIM)

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