ATLAS Distributed Computing Evolution: Developments and Demonstrators Towards HL–LHC

The computing challenges at the HL–LHC require fundamental changes to the distributed computing models that have served experiments well throughout LHC. ATLAS planning for HL–LHC computing started back in 2020 with a Conceptual Design Report outlining various challenges to explore. This was followed in 2022 by a roadmap defining concrete milestones and associated effort required. Today, ATLAS is proceeding further with a set of "demonstrators" with focused R&D in specific topics described in the roadmap. The demonstrators cover areas such as optimised tape writing and access, data recreation on–demand and the use of commercial clouds.