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The ATLAS ROOT-based data formats: recent improvements and performance measurements
Bhimji W., Cranshaw J., van Gemmeren P., Malon D., Schaffer R.D. et al
Dans Journal of Physics: Conference Series - Computing in High Energy and Nuclear Physics (CHEP2012), New York : États-Unis (2012) - http://hal.in2p3.fr/in2p3-00700562
Informatique/Architectures Matérielles
Informatique/Performance et fiabilité
The ATLAS ROOT-based data formats: recent improvements and performance measurements
W. Bhimji, J. Cranshaw1, P. van Gemmeren1, D. Malon1, R.D. Schaffer, I. Vukotic2
1 :  ANL - Argonne National Laboratory
http://www.anl.gov
US Department of Energy – University of Chicago
9700 S. Cass Avenue Argonne, IL 60439
États-Unis
2 :  LAL - Laboratoire de l'Accélérateur Linéaire
http://www.lal.in2p3.fr/
CNRS : UMR8607 – IN2P3 – Université Paris XI - Paris Sud
Centre Scientifique d'Orsay B.P. 34 91898 ORSAY Cedex
France
We detail recent changes to ROOT-based I/O within the ATLAS experiment. The ATLAS persistent event data model continues to make considerable use of a ROOT I/O backend through POOL persistency. Also ROOT is used directly in later stages of analysis that make use of a flat-ntuple based "D3PD" data-type. For POOL/ROOT persistent data, several improvements have been made including implementation of automatic basket optimisation, memberwise streaming, and changes to split and compression levels. Optimisations are also planned for the D3PD format. We present a full evaluation of the resulting performance improvements from these, including in the case of selected retrieval of events. We also evaluate ongoing changes internal to ROOT, in the ATLAS context, for both POOL and D3PD data. We report results not only from test systems, but also utilising new automated tests on real ATLAS production resources which employ a wide range of storage technologies.
ATLAS

Communications avec actes
2012
21/05/2012
Journal of Physics: Conference Series
internationale
396
022006
Institute of Physics Publishing

Computing in High Energy and Nuclear Physics (CHEP2012)
New York
États-Unis
21/05/2012
25/05/2012
W. Bhimji

LAL 12-186