• Created by Unknown User (chamont), last modified on Jan 08, 2008

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Use of the skimmer on Noric machines

The skimmer is only usable on linux, and most of its features will not work outside of SLAC network, because it needs the access to intput ROOT data files, and to the metadata database for the pipeline I data files (at least for the step which is preparing the list of input ROOT data files). This is why it is recommended to use the skimmer only on noric machines, where any new release is installed by its developers.

If one want to use the last release v3r10, he can simply set the relevant shell variables (as described in the user guide) and type : 

/afs/slac/g/glast/ground/DataServer/v3r10/bin/skimmer

Of course, it is sane to define an alias in your Unix account setup files, or add the DataServer bin directory to the Unix PATH.

For what concerns the external tools, skimmer v3r10 depends on :

  1. Perl 5, which should be found with "/usr/bin/env perl".
  2. ROOT 5.10.00 to 5.16.00 : the user can specify $ROOTSYS to any ROOT release, and it will be used as is by the skimmer, but the only validated releases are 5.10.00, 5.14.00g and 5.16.00 ; if not defined, the skimmer will search for $GLAST_EXT/ROOT/v5.10.00/root ; if GLAST_EXT is not defined, it will be set to /nfs/farm/g/glast/u05/GLAST_EXT/rh9_gcc32.

The predefined data kinds

The list of kinds of input data files which can be skimmed is currently hardcoded, and especially targetted to GLAST needs. For each of those kinds, we expect to have a main ROOT tree, with a main ROOT branch. Actually, we distinguish two sets of files : the ones which only rely on predefined ROOT types and have a single level of branches under the main one (the tuple-like files), and the others. The latter typically requires the loading of a dedicated data description library before the skimming.

The last release v3r10 should understand the following types :

  1. merit (tuple-like)
  2. mc (requires libmcRootData.so)
  3. digi (requires libdigiRootData.so)
  4. recon (requires libreconRootData.so)
  5. cal (tuple-like)
  6. svac (tuple-like)
  7. gcr (requires libgcrSelectRootData.so)

Worth to be noted, in the specific case of merit input files, the skimmer will also systematically merge the pointing_history and jobinfo trees and write them to separate output files.

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