UnderstandingI/Opatterns and performance of CMS Data Analysis across T2s worldwide
L. Sala · Journal of Physics Conference Series · 2011
We discuss the I/O patterns and performance of CMS Data Analysis based on measurements on "the bench" as well as operational observations during the initial LHC data taking period. It was observed the default I/O settings for CMS data analysis resulted in poor CPU efficiency and high I/O load at many T2 sites. This effort developed tools to measure CMSSW I/O performance for grid-based analysis. Our work enabled CMSSW developers to understand how new I/O strategies work across the full range of deployed T2 storage solutions. We discuss our results, based upon aggregate statistics collected worldwide.