CERN, the European Laboratory for Particle Physics, is well underway in building the most powerful particle accelerator called LHC (Large Hadron Collider), which will probe deeper into matter than ever before. This circular 27-km long superconducting installation is extremely complex, and its functioning has to be closely monitored. The LHC Logging service is aimed to satisfy the requirement of capturing and storing of any relevant piece of information to track its variation over time. Web-deployed tools have been developed to visualize, correlate and export the data into dedicated off-line analysis tools. The quality of the data, the manageability of the service and the overall system performance are key factors for the service. Oracle technology has been used extensively to support this mission-critical service, which has proven already to be useful during the commissioning phase of individual subsystems of the LHC. The architecture, design and implementation of the LHC Logging service, based on Oracle Database, Application Servers and the Enterprise Manager, are described in this paper
