The CDF online system

Abstract The CDF Online System is described. A VAX cluster acts as the primary control and monitoring environment for a large FASTBUS-based data-acquisition system. The system is highly redundant and allows multiple experiments (or partitions) to run simultaneously on subsets of the experimental apparatus for performing calibrations or diagnostics in parallel. For physics runs, consumer processes residing on any of the VAX computers can access the data in parallel, allowing sophisticated online monitoring to be performed.