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STAR Databases: DB-Types Conditions | Configurations | Calibrations | Geometry | RunLog | Scalers | Tagdb | Run/CodeParams | Production | |
| Offline computing tutorial | Maintained by Jeff Porter |
| Last modified Fri Jul 03 00:19:00 1998 | |
listed items are linked to more detailed discussions on:
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Description: The Conditions Database serves to record the experimental running conditions. The database system is a set of "subsystem" independent databases written to by Online "subsystems" and used to develop calibration and diagnostic information for later analyses. Some important characteristics of the Conditions/DB are:
There are essentially 4 types of use scenarios for the Conditions/DB. (1) Online updates: Each Online sub-system server (or subsystem code directly) needs the capability to update thier database with the data representing the sub-system operation. These updates can be triggered by a periodic (automated) sub-system snap-shots, a manually requested snap-shot, or an alarm generated recording of relevant data. In any of these cases, the update record includes the TimeStamp associated with the measurement of the sub-system data for future de-referencing. (2) Online diagnostics: The snap-shots, which may include a running histogram of Conditions data, should be accessible from the sub-system monitors to diagnose the stability of the control & detector systems and correlations between detector performance and system conditions. (3) Offline diagnostics: The same information as (2) is needed from Offline codes (running, for example, in the Online-EventPool environment) to perform more detailed analyses of the detector performance. (4) Offline calibrations: The conditions/DB data represent the finest grained & most fundamental set of data from which detector calibrations are evaluated (excepting, of course, for the event data). The Conditions data is input to the production of Calibration data and, in some cases, Calibration data may simply be the re-time-stamp of Conditions data by the time interval of the Calibration's stability rather than that of some automated snap-shot frequency.
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Description: The Configuration Database serves as the repository of detector-hardware "set-points". This repository is used to quickly configure the systems via several standard "named" configurations. The important characteristics of the Configuration/DB are;
There are essentially 3 types of use scenarios for the configurations database. (1) Online Registration: A configuration for a sub-system is created through the Online SubSystem Server control by direct manipulation of the subsystem operator. That is, a "tree-structured" object catalog is edited to specify the "named" objects included in the configuration. The individual named objects can, if new, have input values specified or, if old, will be loaded as they are stored. The formed configuration can then be registered for later access by configuration name. There exists an Online GUI to perform these basic tasks (2) Online Configuration: Once registered, a configuration is made available for enabling the detector sybsystem as specified by the configuration's content. The Online RunServer control can requesta named configuration under the Online protocols and parse the subsytem Keys (named collection) to the subsystem servers which access the Configurations/DB directly. (3) Offline use: In general Offline codes will use information derived from the conditions/DB to perform reconstruction/analysis tasks (e.g. not the set-points but the measured points). However, some general information about the setup can be quickly obtained from the Configurations/DB as referenced from the RunLog. This will tell, for example, what set of detectors were enabled for the period in question.
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Description: The Calibration/DB contains data used to correct signals from the detectors into their physically interpretable form. This data is largely derived from the conditions/DB information and event data by reformulating such information into usefull quantities for reconstruction &/or analysis tasks. There are essentially 3 types of use scenarios for the calibrations database. (1) Offline in Online: It is envisioned that much of the calibration data will be done produced via Offline processing running in the Online Event-Pool. These calibration runs will be fed some fraction of the real data produced by the DAQ Event-Builder. This data is then written or migrated into the Calibration/DB for use in Offline production and analyses. (2) Offline in Offline: Further reprocessing of the data in the Offline environment, again with specific calibration codes, can be done to produce additional calibration data. This work will include refinements to original calibration data with further iterations or via access on data not available in the Online Event Pool. Again the calibration data produced is written or migrated to the calibration database which resides in Offline. (3) Offline reconstruction & analyses: The calibration data is used during production and analysis tasks in, essentially, a read-only mode.
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Description: The Geometry database stores the geometrical description of the STAR detectors and systems. It is really part of the calibration database except that the time-constant associated with valid entries into the database will be much longer than typical calibration data. Also, it is expected that many applications will need geometrical data from a variety of sub-systems while not needing similar access to detector-specific (signal) calibration data. Thus the access interface to the geometry database should be segragated from the calibration database in order to optimize access to its data. There are a few generic categories of geometry uses that while not independent may suggest indecate differen access scenarios. (1) Offline Simulations: (2) Offline Reconstruction: (3) Offline Analyses & Event Displays:
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Description: The RunLog holds the summary information describing the contents of an experimental run and "pointers" to the detailed information (data files) that are associated with the run. A more complete description can be found on the Online web pages. (1) Online Generation: The RunLog begins in Online which the run is registered, stored when the run is enabled, and updated when the run has ended. Furhter updates from Online may be necessary e.g. once verification is made as to the final store of the event data on HPSS. (2) Online (& Offline) Summaries: The RunLog can be loaded and properties displayed in order to assertain progress toward overall goals that span Runs. (3) Offline Navigation : The RunLog will have a transient representation in the offline infrustructure which will allow the processes to navigate to other database entities (i.e. Configurations & Scalers)
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