Characteristics of the workload on ASCI Blue-Pacific, a 336-node IBM SP2 SMP-cluster machine at Lawrence Livermore National Laboratory (LLNL), are discussed in this paper. It is shown that majority of jobs have very short inter-arrival time and execution time with relatively long waiting delay. It is also shown that the node and memory demands of jobs are surprisingly small. This findings strongly encourage the use of a scheduling technique which combines both space- and time-sharing to improve system performance. Contrary to our expectations, there is little correlation between job's execution time and resource demands. Although large jobs constitute a relatively small fraction of total job population, they consume most of the resources.