A Linux cluster is a connected array of Linux computers or nodes that work together and can be viewed and managed as a single system. Nodes are usually connected by fast local area networks, with each node running its own instance of Linux. Nodes may be physical or virtual machines, and they may be separated geographically. Each node includes storage capacity, processing power and I/O (input/output) bandwidth. Multiple redundant nodes of Linux servers may be connected as a cluster for high availability (HA) in a network or data center, where each node is capable of failure detection and recovery.
IT organizations use Linux clusters to reduce downtime and deliver high availability of IT services and mission-critical workloads. The redundancy of cluster components eliminates single points of failure. Linux clusters may be connected nodes of servers, storage devices or virtualized containers. A server cluster is a group of linked servers that work together to improve system performance, load balancing and service availability. If a server fails, other servers in the cluster can take over the functions and workloads of the failed server.
Compared to a single computer, a Linux cluster can provide faster processing speed, larger storage capacity, better data integrity, greater reliability and wider availability of resources. Clusters are usually dedicated to specific functions, such as load balancing, high availability, high performance, storage or large-scale processing. Compared to a mainframe computer, the amount of power and processing speed produced by a Linux cluster is more cost effective. The networked nodes in a cluster also create an efficient, distributed infrastructure that prevents bottlenecks, thus improving performance. SUSE Linux High Availability Extension provides open source HA clustering that can be deployed in physical or virtual environments.