Studying ROOT I/O performance with PROOF-Lite

Parallelism aims to improve computing performance by executing a set of computations concurrently. Since the advent of today's many-core machines the full exploitation of the available CPU power has been one of the main challenges. In High Energy Physics (HEP) final data analysis the bottleneck is not only the available CPU but also the available I/O bandwidth. Most of today's HEP analysis frameworks depend on ROOT I/O. In this paper we will discuss the results obtained studying the ROOT I/O performance using PROOF-Lite, a parallel multi-process approach whose results can be directly applied to the generic case of many jobs running concurrently on the same machine. We will also discuss the impact of running the applications in virtual machines.