a computer cluster may be a simple two-node system which just connects two personal computers, or may be a very fast supercomputer. a basic approach to building a cluster is that of a beowulf cluster which may be built with a few personal computers to produce a cost-effective alternative to traditional high performance computing. an early project that showed the viability of the concept was the 133-node stone soupercomputer. the developers used linux, the parallel virtual machine toolkit and the message passing interface library to achieve high performance at a relatively low cost.