The communications system currently in use is called gigabit, which is supposed to be several times faster than previous systems. But the performance has not matched the prediction. So part of the SCL team's research is to determine how best to optimize gigabit. And that's one of the major problems they're looking at here at Ames Lab. So they're tackling what is probably the most significant problem in realizing the potential that PC clusters have.
Configuration also has a lot to do with how well large networks of PC clusters perform.
You can arrange them in lots of different ways, and the further one computer has to go to communicate with another, the more arrangements you have. So there's a traffic-directing problem to deal with. In addition, Halstead reminds us of the obvious issue. There's a definite storage concern for a large cluster network. Also, all the energy that goes into a computer comes out as heat, so you'll use more power for air conditioning.