Summary of User Requirements for Calibration and Alignment Database Magali Gruwé CERN PH/AIP ALICE Offline Week Alignment and Calibration Workshop February 22 nd 2005

2 Magali Gruwé CERN PH/AIP ALICE Offline Week, February 22 nd, 2005 Layout  Context  Call for User Requirements  Outcome of questionnaire  Answers  Remaining questions  Conclusion

3 Magali Gruwé CERN PH/AIP ALICE Offline Week, February 22 nd, 2005 Context  The ALICE off-line group is:  Compiling an extensive set of user requirements  Evaluating the various data sources, relation with other DB or raw data  Estimating the volume, update frequency, access pattern and run-time environment  We need to have a fair understanding of :  Use cases  DB content  Implementation of tools for DB population, query, information retrieval and communications with other DB  Definition of development responsibilities  Design and building of the necessary computing infrastructure

4 Magali Gruwé CERN PH/AIP ALICE Offline Week, February 22 nd, 2005 Layout  Context  Call for User Requirements  Outcome of questionnaire  Answers  Remaining questions  Conclusion

5 Magali Gruwé CERN PH/AIP ALICE Offline Week, February 22 nd, 2005 Call for user requirements  Essential parameters of the Alignment and Calibration DBs:  Access pattern and frequency  Only offline reconstruction?  Typical record size  Very difficult to estimate from first principles  Frequency of updates  We expect the majority of the updates to be infrequent  This probably will not be the case  Validity range parameters  Run, event, time, version – what else?  These all have to come from the user community More details/explanations in next slides…

6 Magali Gruwé CERN PH/AIP ALICE Offline Week, February 22 nd, 2005 Questions to be answered by detector community (I):  Context:  The alignment and calibration constants will be ROOT files, registered in a distributed file catalogue. The files will have proper tags, described in the AliEn (gLite) metadata catalogue:  validity period – run, event, time  Version  Questions:  What type and size of Root objects will be needed for the alignment and calibration procedures?  For example:  One calibration object could be a set of gain constants of a calorimeter, written in a root file. This object will have a certain size and will be valid for a given period of time, until the next calibration is taken or the present one is refined (new version).

7 Magali Gruwé CERN PH/AIP ALICE Offline Week, February 22 nd, 2005 Questions to be answered by detector community (II):  Questions (cont’d)  How frequently will these root objects have to be updated (new version produced)?  How frequently will these root objects have to be accessed?  What kind of and how much access to external databases will be needed?  External databases could be:  Construction database (DCDB)  ECS  DAQ  DCS  Trigger  HLT

8 Magali Gruwé CERN PH/AIP ALICE Offline Week, February 22 nd, 2005 Layout  Context  Call for User Requirements  Outcome of questionnaire  Answers  Remaining questions  Conclusion

9 Magali Gruwé CERN PH/AIP ALICE Offline Week, February 22 nd, 2005 Answers to questionnaire  Answers received from all 14 detectors  Some by mail  Last ones during the workshop Thank you all!!  But:  Some are still preliminary:  Need update  Most are incomplete:  Need to be thought about and completed  Some show misunderstanding:  Need clarifications from both sides

10 Magali Gruwé CERN PH/AIP ALICE Offline Week, February 22 nd, 2005 Outcome of questionnaire (I)  Three types of objects:  Calibration related  Alignment related  Dead/bad channel maps  Note:  Some detectors specify “one object per channel”  This will NOT happen: there will be ONE object for all channels  Examples:  One “gain” object being an array containing all gains of all channels  One calibration object being and array of all gains and pedestals of all channels

11 Magali Gruwé CERN PH/AIP ALICE Offline Week, February 22 nd, 2005 Outcome of questionnaire (II)  Size: (rough counting, from information sent by )  ITS: ~80 MB  TRD: few MB  PHOS: ~1MB  EMCAL: ~1MB  RICH: ~1MB?  CRT: few kB  MUON: ~70MB  ZDC: few kB  V0: 2.4 kB  PMD: ~9MB  TOF: ~7MB  TPC: ???

12 Magali Gruwé CERN PH/AIP ALICE Offline Week, February 22 nd, 2005 Outcome of questionnaire (III)  Update frequency:  In general: anything between 1/run and 1/year  Note:  Some parameters vary quickly, but update frequency will not be higher than once per run. Stored objects would be histograms for example.  Example:  One drift velocity object being a histogram with the time dependence of the drift velocity within a run

13 Magali Gruwé CERN PH/AIP ALICE Offline Week, February 22 nd, 2005 Outcome of questionnaire (IV)  Access pattern/frequency:  For most detectors: no answer, or there seems to be confusion with update frequency  Questions:  How often do you need the data?  Only in reconstruction jobs?  Is there an iterative procedure?  Clearly, there is better understanding thanks to workshop

14 Magali Gruwé CERN PH/AIP ALICE Offline Week, February 22 nd, 2005 Outcome of questionnaire (V)  External Database access:  Very little input from detectors:  Most detectors said:  No external database access needed  Or did/could not answer  Other detectors:  FMD:  Need to know how the detector was operated at the time of data acquisition, beam species, etc…  ITS:  Construction/geometry/calibration databases???  TRD:  ESD only?  CRT:  Need run header  ZDC:  General run conditions  Machine Database!  V0:  General trigger  T0:  DCDB

15 Magali Gruwé CERN PH/AIP ALICE Offline Week, February 22 nd, 2005 Conclusions  Thanks again to detector representatives for the answers to the questionnaire  s/discussions/presentations  We received a lot more information during the workshop than via s  These give us an excellent starting point  Problem with respect to size of objects needed for some detectors:  Need to find a way to reduce it  A note is being written summarizing our understanding of detectors requirements. It will be circulated soon.  Home work for detector groups:  Think again about requirements (with the highlight of the other detectors’ presentations)  And more specifically about External Database access