A computer cluster consists of a set of loosely connected or tightly connected computers that work together so that in many respects they can be viewed as a single system.
The components of a cluster are usually connected to each other through fast local area networks („LAN“), with each node (computer used as a server) running its own instance of an operating system. Computer clusters emerged as a result of convergence of a number of computing trends including the availability of low cost microprocessors, high speed networks, and software for high performance distributed computing.
Attributes of clusters
Computer clusters may be configured for different purposes ranging from general purpose business needs such as web-service support, to computation-intensive scientific calculations. In either case, the cluster may use a high-availability approach. Note that the attributes described below are not exclusive and a „compute cluster“ may also use a high-availability approach, etc. A load balancing cluster with two servers and 4 user stations „Load-balancing“ clusters are configurations in which cluster-nodes share computational workload to provide better overall performance.
For example, a web server cluster may assign different queries to different nodes, so the overall response time will be optimized.
Design of Clusters
However, approaches to load-balancing may significantly differ among applications, e.g. a high-performance cluster used for scientific computations would balance load with different algorithms.
A load balancing cluster with two servers and 4 user stations „Load-balancing“ clusters are configurations in which cluster-nodes share computational workload to provide better overall performance.
Clusters are usually deployed to improve performance and availability…
Clusters are usually deployed to improve performance and availability over that of a single computer, while typically being much more cost-effective than single computers of comparable speed or availability. Computer clusters have a wide range of applicability and deployment, ranging from small business clusters with a handful of nodes to some of the fastest supercomputers in the world such as IBM’s Sequoia.