Distributed data access and resource management in the D0 SAM system

SAM (Sequential Access through Meta-data) is the data access and job management system for the D0 high energy physics experiment at Fermilab. The SAM system is being developed and used to handle the Petabyte-scale experiment data, accessed by hundreds of D0 collaborators scattered around the world. In this paper, we present solutions to some of the distributed data processing problems from the perspective of real experience dealing with mission-critical data. We concentrate on the distributed disk caching, resource management and job control. The system has elements of Grid computing and has features applicable to data-intensive computing in general.