Beowulf originally referred to a specific computer built in 1994 by Thomas Sterling and Donald Becker at NASA.

At this level, however, most are by no means just assemblages of commodity hardware; custom design work is often required for the nodes (often blade servers), the networking, and the cooling systems.

Beowulf also uses commodity software like the FreeBSD, Linux or Solaris operating system, Parallel Virtual Machine (PVM) and Message Passing Interface (MPI).

In most cases client nodes do not have keyboards or monitors, and are accessed only via remote login or possibly serial terminal.

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 a standard Linux distribution without any additional software.

If you have two networked 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.

These include: The following are no longer maintained: A cluster can be set up by using Knoppix bootable CDs in combination with OpenMosix.