Most cases were run for a single replication of about 100 weeks of simulated time, but about 50 cases were selected for further scrutiny. This required 50 more replications of each case, for a total of about 8500 replications. We estimated this to take about 3 months of CPU time on a single SparcStation 2 such as hierarchy. Using our virtual supercomputer, the entire job was done in four days of real time. In addition, we did extensive model validation runs and a number of false starts before getting it right.
More speed is available by using more hosts.
The approach is not limited to Sun computers,as our Pentium PC demonstrated. Anything that supports UNIX stream sockets can be used. This allows other fast computers to be added by the simple expedient of getting an account, recompiling the simulation for that machine type, and adding the host name to the server list of target hosts. In conclusion, our approach gives supercomputer speed at very little cost.