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The resources of the HPC centers are a potential aid to meet the future challenges of HL-LHC [1] in terms of computational requirements. Spanish HPC centers have recently been used to implement all necessary edge services to integrate resources into the LHC experiment workflow management system. In this article, we describe the integration of ATLAS with the extension plan to other LHC experiments. We chose to configure a dedicated ARC-CE [2] and interact with the HPC login and transfer nodes using ssh commands. The repository that includes a partial copy of the ATLAS experiment software on CVMFS is packaged in a singularity image to overcome network isolation for HPC nodes and reduce software requirements. ATLAS provided the initial container, and the authors adapted it to the specific HPC environment. This article shows the Spanish contribution to the simulation of experiments after the Spanish Ministry of Science agreement and the Barcelona Supercomputing Center (BSC), the center that operates MareNostrum 4. Finally, we discuss some challenges to take advantage of the next generation of HPC machines with heterogeneous architecture combining CPU and GPU.

25th International Conference on Computing in High-Energy and Nuclear Physics, vCHEP2021, Online, France, 17 May 2021 - 21 May 2021; The European physical journal / Web of Conferences 251, 02002 - (2021). doi:10.1051/epjconf/202125102002, The High Luminosity LHC project at CERN, which is expected to deliver a ten-fold increase in the luminosity of proton-proton collisions over LHC, will start operation towards the end of this decade and will deliver an unprecedented scientific data volume of multi-exabyte scale. This vast amount of data has to be processed and analysed, and the corresponding computing facilities must ensure fast and reliable data processing for physics analyses by scientific groups distributed all over the world. The present LHC computing model will not be able to provide the required infrastructure growth, even taking into account the expected evolution in hardware technology. To address this challenge, several novel methods of how end-users analysis will be conducted are under evaluation by the ATLAS Collaboration. State-of-the-art workflow management technologies and tools to handle these methods within the existing distributed computing system are now being evaluated and developed. In addition the evolution of computing facilities and how this impacts ATLAS analysis workflows is being closely followed., Published by EDP Sciences, Les Ulis

The ATLAS Spanish Tier-1 and Tier-2s have more than 15 years of experience in the deployment and development of LHC computing components and their successful operations. The sites are already actively participating in, and even coordinating, emerging R&D computing activities and developing new computing models needed for the Run3 and HighLuminosity LHC periods. In this contribution, we present details on the integration of new components, such as High Performance Computing resources to execute ATLAS simulation workflows. The development of new techniques to improve efficiency in a cost-effective way, such as storage and CPU federations is shown in this document. Improvements in data organization, management and access through storage consolidations (“data-lakes”), the use of data caches, and improving experiment data catalogs, like Event Index, are explained in this proceeding. The design and deployment of new analysis facilities using GPUs together with CPUs and techniques like Machine Learning will also be presented. Tier-1 and Tier-2 sites, are, and will be, contributing to significant R&D in computing, evaluating different models for improving performance of computing and data storage capacity in the High-Luminosity LHC era.