1. Timm M. Steinbeck - Kirchhoff Institute of Physics - University Heidelberg 1 HLT and the Alignment & Calibration DB

2. Timm M. Steinbeck - Kirchhoff Institute of Physics - University Heidelberg 2 Contents ● HLT Alignment & Calibration Data Flow ● HLT Alignment & Calibration Data Usage ● HLT Alignment & Calibration DB Usage

3. Timm M. Steinbeck - Kirchhoff Institute of Physics - University Heidelberg 3 HLT Alignment & Calibration Data Flow Alignment & Calibration Data ● Reaches HLT's front-end-processor nodes – From D-RORC DDL splitter ● Can be processed by detector specific components inside the HLT chain ● Processed Results can be – sent to HLT reconstruction components for inclusion – sent to HLT output and DAQ for storage – sent to components to feed data directly into DB – discarded ● Only raw alignment & calibration data is stored

4. Timm M. Steinbeck - Kirchhoff Institute of Physics - University Heidelberg 4 AlCal Data Output via HLT Output ALICE DAQ LDCs HLT FEPs HLT Calibration Components HLT Reconstruction Components HLT Output Components Processed Calibration Data is output via HLT Output Nodes to DAQ HLT-LDCs DDL Splitters DDLs

5. Timm M. Steinbeck - Kirchhoff Institute of Physics - University Heidelberg 5 AlCal Data Output via DB Components ALICE DAQ LDCs HLT FEPs HLT Calibration Components HLT Reconstruction Components HLT DB Write Components Alignment & Calibration DB Processed Calibration Data is output via HLT Components to AlCal DB DDL Splitters Network

6. Timm M. Steinbeck - Kirchhoff Institute of Physics - University Heidelberg 6 No AlCal Data Output from HLT ALICE DAQ LDCs HLT FEPs HLT Calibration Components HLT Reconstruction Components Only Raw Calibration Data is stored by DAQ DDL Splitters

7. Timm M. Steinbeck - Kirchhoff Institute of Physics - University Heidelberg 7 HLT AlCal Data Usage ● Processed Alignment/Calibration Information is needed by HLT reconstruction components ● Process it (from raw Alignment/Calibration data) close to where it is needed ● Processing has high local parts (like normal event processing/reconstruction) ● Utilize locality by distributing processing on cluster nodes like normal event

8. Timm M. Steinbeck - Kirchhoff Institute of Physics - University Heidelberg 8 HLT DB Usage ● Reduced DB accesses ● No DB read accesses necessary – AlCal data arrives automatically in HLT through readout – Maybe read in last values on HLT restart, but can be stored internally as well ● Write accesses only if HLT processed data is to be stored – Frequency of detector alignment/calibration – Data volume most likely less than raw alignment/calibration data – Up to detector groups to determine/decide

9. Timm M. Steinbeck - Kirchhoff Institute of Physics - University Heidelberg 9 Feasibility ● Feasibility depends mainly on amount of computing required for processing – 100 CPUs for processing one set of calibration data with 100 calibrations per second probably not feasible