Computer cluster
A computer cluster is a group of connected computers that work together as a parallel computer. One of the more popular implementations is a cluster with nodes running Linux as the OS and Beowulf software (both free software) to implement the parallelism. Sun Microsystems has also released a clustering product called Grid engine. There are fundamentally four types of clusters:
- Director based clusters
- Two-node clusters
- Multi-node clusters
- Massively Parallel clusters
Clustering can provide significant performance versus price. The System X supercomputer at Virginia Tech, the third most powerful supercomputer on Earth as of November 2003, is a computer cluster of 1100 Apple Power Macintosh G5s running Mac OS X. The total cost of the system is $5.2 million, a tenth of the cost of slower mainframe supercomputers.
Clusters were originally developed by DEC in the 1980s. They not only support parallel computing, but also shared file systems and peripheral devices. They are supposed to give you the ability to use any program without slowdown or other problems.
A cluster of computers is sometimes referred to as a server farm.
In the GNU/Linux world, there is also cluster software, such as DistCC, Mosix and its free counterpart openMosix. Mosix and openMosix provide automatic process migration in a homogeneous cluster of GNU/Linux machines, while DistCC provides parallel compilation when using GCC.
DragonFly BSD, a recent fork of FreeBSD 4.8 is being redesigned at it's core to enable native clustering capabilities.