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Offline framework for conditions data

Offline framework for conditions data. L.Betev TPC commissioning meeting Geneva, February 17, 2006. Outline. Conditions data in Offline Content and access Status of offline framework and plans. Conditions data in Offline

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Offline framework for conditions data

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  1. Offline framework for conditions data L.Betev TPC commissioning meeting Geneva, February 17, 2006

  2. Outline • Conditions data in Offline • Content and access • Status of offline framework and plans

  3. Conditions data in Offline • Conditions data are stored and accessible by the applications on the GRID • Treating all source databases as potentially containing conditions information and as “closed”, i.e. only accessible at CERN • It would be difficult to provide access methods to all DBs from the production and analysis code • The conditions DB framework is providing access methods to all external DBs • Conditions data stored as read only ROOT files: • Object store technology already incorporated in the ALICE offline Conditions DB relations in ALICE

  4. Conditions DB relations in ALICE (2) • Conditions data access in a Grid distributed production and analysis environment: • The root files are registered in the Grid Distributed File Catalogue: • No need for distributed DBMS in a traditional sense and with all accompanying problems (remote access, replication, authentication, load) – a very big plus • Assures worldwide access to all files and associated tags • Drawbacks: • Replication of information – potentially large parts of ‘external’ DBs have to be put in the offline conditions DB • However the same is true for all LHC experiments

  5. Physicsdata files calibration procedures API ECS DAQ API calibration files Trigger API Calibration classes GRID FC: metadata file store DCS API AliRoot DCDB API API HLT API External sources of conditions data and relations to offline

  6. Conditions DB – content and access • Update frequency: • The condition DB will have rather infrequent updates (max: once per run) • The objects themselves can have rich internal structure with finer granularity, depending on the detector calibration / alignment needs • Access framework: • Simple user interface and data identification (strings) • Automatically get the right valid object • Modification of the objects is handled through versioning • Same interface for different types of data sources (local file, Grid)

  7. Data organisation - simple filesystem-like storage: • Calibration/DETECTOR/FirstRun-LastRun.version

  8. Status of the access framework • AliRoot implementation: • Classes to put/get conditions objects are ready and tested by all ALICE detector groups • Access methods: • GRID file and metadata storage (AliEn GRID File catalogue) – deployed • Conditions data dump in local files - expert use, new versions of conditions, ‘disconnected from the GRID’ mode – deployed • Combination of the above - deployed

  9. Status of the access framework (2) • Current issues: • Availability of conditions data • ‘Quasi-online’ first pass reconstruction – good enough version of the conditions data should be available almost immediately • Who provides what: offline is a pure consumer of conditions data – should make sure that the methods and procedures exist to store the data in the relevant ‘external’ DBs • APIs to external sources • Access to some of the DBs not solved yet (especially LHC machine information)

  10. Conditions DB – automatic information gathering • Automated system – Shuttle: • Collecting conditions data from external DB at predetermined time intervals (for example at the end of every run) • Processing collected data using detector-specific preprocessor • Storing conditions data in the Conditions DB

  11. Conditions DB – information gathering (2) • Similar systems can be used to process conditions data from other sources: • Only new interfaces needed • The processing of the data is done in AliRoot (no change of framework) • Allows detector groups to do analysis and reduction of the raw data volume before storing it in the Conditions DB • The Shuttle program access to DCS and DAQ DBs is deployed and tested: • Real life test (Summer 2006) running with detector data – ALICE TPC cosmic ray tests

  12. Summary on status and plans • GRID/ROOT based Conditions DB framework ready • Implementation in detector reconstruction and analysis code ongoing • Automatic gathering of conditions data from external sources – prototype ready • Tests with real detector data – Sumer 2006 • Continuous tests ‘on the GRID’ as part of the ALICE PDC’06/LCG SC4 • Current issues • Availability of conditions data to offline from external sources • ‘good enough’ conditions data available for the first round of ‘quasi-online’ processing

  13. Status of TPC

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