In the summer of 1994 Thomas Sterling and Don Becker, working at the Center of Excellence in Space Data and Information Sciences (CESDIS) at the Goddard Space Flight Center in Greenbelt Maryland, built a cluster computer consisting of 16 processors connected by Ethernet. They called their machine Beowulf. The machine was an instant success and their idea of providing COTS (Commodity off the shelf) based systems to satisfy specific computational requirements quickly spread through NASA and into the academic and research communities. A non-technical measure of success is the observation that researchers within the High Performance Computer community are now referring to such machines as "Beowulf Class Cluster Computers." That is, Beowulf clusters are now recognized as genre within the HPC community.
The COTS industry now provides fully assembled subsystems (microprocessors, motherboards, disks and network interface cards). Mass market competition has driven the prices down and reliability up for these subsystems. The development of publicly available software, in particular, the Linux operating system, the GNU compilers and programming tools and the MPI and PVM message passing libraries, provide hardware independent software.
In the taxomony of parallel computers, Beowulf clusters fall somewhere between MPP (Massively Parallel Processors, like the nCube, CM5, Convex SPP, Cray T3D, Cray T3E, etc.) and NOWs (Networks of Workstations). The Beowulf project benefits from developments in both these classes of architecture. A Beowulf class cluster computer is distinguished from a Network of Workstations by several subtle but significant characteristics, e.g., the nodes in the cluster are dedicated to the cluster; since the interconnection network is isolated from the external network, the network load is determined only by the application being run on the cluster; because all the nodes in the cluster are within the administrative jurisdiction of the cluster, the interconnection network for the cluster is not visible from the outside world so the only authentication needed between processors is for system integrity.
The Beowulf Project grew from the first Beowulf machine and likewise the Beowulf community has grown from the NASA project. Like the Linux community, the Beowulf community is a loosely organized confederation of researcher and developer. Each organization has its own agenda and its own
set of reason for developing a particular component or aspect of the Beowulf system. As a result, Beowulf class-cluster computers range from several node clusters to several hundred node clusters.
