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Overview of Beowulf Systems | | | | | | | | | A Beowulf is a collection of personal computers (PCs) interconnected by widely available networking technology running any one of several open-source Unix-like operating systems. Beowulf programs are usually written in C or FORTRAN, adopting a message passing model of parallel computation but other open, standards based approaches are possible, including process level parallelism, shared memory (OpenMP, BSP), other languages (Java, LISP, FORTRAN90), and other communication strategies (RPC, RMI, CORBA). This definition, albeit a bit lengthy, captures the complete essence of the factors contributing to what makes a system a Beowulf. | | | | | | | | | The PCs benefit from the economy of scale of the mass production of millions of microprocessors, memory chips, input/output (I/O) controllers, and motherboard chip sets as well as the mass production of the systems in which the components are incorporated the complete personal computers found in offices, labs, and homes. These same PCs are the constituent elements of Beowulf high performance parallel computers. Beowulfs, with no special hardware development costs or lead times, exploit the exceptional (almost extraordinary) cost effectiveness of these complete systems. ''Parts by dawn, processing by dusk" is an apt description of the Beowulf revolution. While many commercial massively parallel processors (MPPs) use the same processor, memory, and controller chips that are employed by both PCs and Beowulfs, they also must incorporate custom "glue" (internal communications networks, packaging, advanced compiler technologies, etc.), that greatly increase cost and development time. Consequently, the advantages of using mass-market commodity-off-the-shelf (M2COTS) components in these systems is significantly reduced. Beowulfs use only mass-market components and are not subject to the delays and costs associated with custom parts and custom integration. | | | | | | | | | The interconnection networks that allow processors to work together also benefit from the same mass-market economy that provides low-cost processing. Derived from technology developed over many years to provide robust, scalable, high bandwidth local area networks (LANs), the system area network (SAN) integrating the processors of a Beowulf is implemented with COTS communications subsystems including network interface controllers and switches. Among those available, Ethernet in its various configurations and capacities is the technology most widely used. A Beowulf system of a hundred nodes or more may be integrated by a system area network derived from Fast Ethernet LAN technology at a total cost of about a quarter of that of the entire system. | | | | |
