About the Worldwide LHC Computing Grid

The Worldwide LHC Computing Grid (WLCG) is a globally distributed, tiered computing infrastructure that provides near real-time access to LHC data for a community of over 12,000 scientists from more than 100 nationalities, based at institutes in over 70 countries.

The scale and complexity of data from the LHC is unprecedented. This data needs to be stored, easily retrieved and analysed by physicists all over the world. This requires massive storage facilities, global networking, immense computing power, and, of course, funding.

Using the Grid

The WLCG computing model has been designed to be very flexible, to allow for worldwide access and analysis in near real-time.

WLCG provides seamless access to a wide range of computing resources, including data storage, processing power, sensors, visualization tools, and other services. Users submit jobs through one of the many entry points to the system. These jobs typically involve processing specific datasets using software provided by the LHC experiments.

The Grid authenticates users, verifies their credentials, and identifies available sites capable of providing the required resources. Researchers do not need to know where the computing resources are located; the Grid transparently delivers computing power and storage on demand, enabling them to focus on their scientific work.

From CERN to the world via WLCG

Long Shutdown 3: 2026 – ~2028

CERN is currently in Long Shutdown 3 (LS3), a major maintenance and upgrade programme running until around 2028, involving thousands of experts across its accelerator complex and experimental facilities. The centrepiece of LS3 is the High-Luminosity LHC upgrade, which will significantly increase the number of particle collisions and enable new scientific discoveries. Major detector enhancements, infrastructure improvements, and facility renovations are also underway to prepare experiments for the increased data volumes and performance demands of future operations.

LHC Run 3 – 2022-2025

LHC Run 3 concluded in mid-2026 and proved even more demanding than its predecessors. During the run, the LHC experiments collected as much data as had been gathered during Runs 1 and 2 combined.

This achievement resulted in a dramatic increase in the volume of data distributed across the WLCG, making it accessible to physicists around the world. At the same time, the computing requirements of ALICE, ATLAS, CMS, and LHCb continued to grow, driven by increasingly ambitious physics programmes and the enhanced precision of the experiments’ detectors.

LHC Run 4: HiLumi-LHC, ~2029-2032

The High-Luminosity Large Hadron Collider (HL-LHC) project aims to crank up the performance of the LHC in order to increase the potential for discoveries after 2029.

Requirements for data and computing will skyrocket dramatically during this time. The needs for processing, network transfer and storage are expected to increase many times over and above what technology evolution will provide.

As a consequence, partnerships – such as those with CERN openlab and other programmes of R&D – are essential to investigate how the computing models could evolve to address these needs. They will focus on applying more intelligence into filtering and selecting data as early as possible. Investigating the distributed infrastructure itself (the grid) and how one can best make use of available technologies and opportunistic resources (e.g. grid, cloud, HPC, volunteer, etc), and most notably improving software performance to optimise the overall system.

In 2017 the High Energy Physics community produced a roadmap Community White Paper (arXiv:1712.06982) that explores these software challenges and describes a number of potential mechanisms by which the community can address these problems of capacity and efficiency that will be faced during the next decade.