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Beowulf is a design for high-performance parallel computing clusters on inexpensive personal computer hardware. Originally developed by Thomas L. Sterling and Donald Becker at NASA, Beowulf systems are now deployed worldwide, chiefly in support of scientific computing.
A Beowulf cluster is a group of usually identical PC computers running a Free and Open Source Software (FOSS) Unix-like operating system, such as Linux or BSD. They are networked into a small TCP/IP LAN, and have libraries and programs installed which allow processing to be shared among them.
There is no particular piece of software that defines a cluster as a Beowulf. Commonly used parallel processing libraries include MPI (Message Passing Interface) and PVM (Parallel Virtual Machine). Both of these permit the programmer to divide a task among a group of networked computers, and recollect the results of processing. It is a common misconception that any software will run faster on a Beowulf. The software must be re-written to take advantage of the cluster, and specifically have multiple non-dependent parallel computations involved in its execution.
The name comes from the main character in the Old English epic Beowulf.
Original Beowulf HOWTO Definition
The following is the definition of a Beowulf cluster from the [http://www.ibiblio.org/pub/linux/docs/HOWTO/archive/Beowulf-HOWTO.html original Beowulf HOWTO] published under the Linux Documentation Project in 1998.
:Beowulf is a multi computer architecture which can be used for parallel computations. It is a system which usually consists of one server node, and one or more client nodes connected together via Ethernet or some other network. It is a system built using commodity hardware components, like any PC capable of running Linux, standard Ethernet adapters, and switches. It does not contain any custom hardware components and is trivially reproducible. Beowulf also uses commodity software like the Linux operating system, Parallel Virtual Machine (PVM) and Message Passing Interface (MPI). The server node controls the whole cluster and serves files to the client nodes. It is also the cluster's console and gateway to the outside world. Large Beowulf machines might have more than one server node, and possibly other nodes dedicated to particular tasks, for example consoles or monitoring stations. In most cases client nodes in a Beowulf system are dumb, the dumber the better. Nodes are configured and controlled by the server node, and do only what they are told to do. In a disk-less client configuration, client nodes don't even know their IP address or name until the server tells them what it is.
:One of the main differences between Beowulf and a Cluster of Workstations (COW) is the fact that Beowulf behaves more like a single machine rather than many workstations. In most cases client nodes do not have keyboards or monitors, and are accessed only via remote login or possibly serial terminal. Beowulf nodes can be thought of as a CPU + memory package which can be plugged in to the cluster, just like a CPU or memory module can be plugged into a motherboard.
:Beowulf is not a special software package, new network topology or the latest kernel hack. Beowulf is a technology of clustering Linux computers to form a parallel, virtual supercomputer. Although there are many software packages such as kernel modifications, PVM and MPI libraries, and configuration tools which make the Beowulf architecture faster, easier to configure, and much more usable, one can build a Beowulf class machine using standard Linux distribution without any additional software. If you have two networked Linux computers which share at least the /home file system via NFS, and trust each other to execute remote shells (rsh), then it could be argued that you have a simple, two node Beowulf machine.
Operating systems
Presently, there are a number of different Linux distributions and one BSD that are designed for building Beowulf clusters. These include:
* ClusterKnoppix (based on Knoppix)
* dyne:bolic (geared towards multimedia production)
* Rocks Cluster Distribution
* Scyld
* DragonFly BSD
A cluster can be set up by using Knoppix bootable CDs in combination with OpenMosix. The computers will automatically link together, without need for complex configurations, to form a Beowulf cluster utilizing all CPUs and RAM in the cluster. This type of system is scalable to a nearly unlimited number of computers.
Examples
* Kentucky Linux Athlon Testbed (KLAT2)
* Stone Soupercomputer
* [http://beowulf.cheme.cmu.edu/ Carnegie Mellon University, Process Systems Engineering Beowulf Cluster]
* [http://www.iss.soton.ac.uk/research/iridis/ Southampton University, Information Systems Services, Iridis Beowulf Cluster]
* [http://www.asgard.ethz.ch/ Asgard - Beowulf Computing at the Swiss Federal Institute of Technology]
Other software solutions
* Sun Grid Engine
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