From detailed analysis of IO pattern of the HEP applications to benchmark of new storage solutions

The problem of file access on the site level has been one of the main issues since the start of the WLCG project. A lot of studies have already been performed using both industry standard benchmarks and actual physicist jobs. However, such studies are typically bound to one particular LHC experiment supported on a given site and/or one type of job. In this paper, we present an application suitable for detailed study of applications' file access behavior. We have also developed an application for exact replaying of IO requests of the previously run applications. This enables to benchmark performance of solutions without a need of installing the whole working environment.