By analysing large data-sets on jobs processed in major computing centres, we study how operations management principles apply to these modern day processing plants. We show that Little's Law on long-term performance averages holds
to computing centres, i.e. work-in-progress equals throughput rate multiplied by process lead time. Contrary to traditional
manufacturing principles, the law of variation does not hold to computing centres, as the more variation in job lead
times the better the throughput and utilisation of the system. We also show that as the utilisation of the system increases
lead times and work-in-progress increase, which complies with traditional manufacturing. In comparison with current
computing centre operations these results imply that better allocation of jobs could increase throughput and utilisation,
while less computing resources are needed, thus increasing the overall efficiency of the centre. From a theoretical point
of view, in a system with close to zero set-up times, as in the case of computing centres, the law of variation does not
hold. We observe that the more variation in job lead times and resource usage, the higher the throughput of the system.