Server Cluster — What is it anyway?
What is a server cluster?
A server cluster is a collection of independent servers working as a system that enables clients access to services. When one computer in a cluster fails, the system’s workload is rearranged so that tasks get redirected to another machine in the server cluster. Server clusters are used to make sure that people can always access important resources on the servers.
Server clusters are designed to handle applications that use a large amount of memory or that are associated with frequently updated data. Server clusters are usually used for file servers, print servers, database servers, and messaging servers.
It is important for companies to maintain high availability server clusters. When a cluster is highly available, it can endure micro-failures while still allowing people to use the applications and data it houses. A high-availability server cluster gives users access to a service for a high percentage of time while mitigating the effects of unscheduled outages.
What does a server cluster do?
Each server within a server cluster houses and manages its components and maintains a copy of the operating system and the applications or services that it manages.
Similarly, only one server at a time manages common components such as common disks, disk arrays and the connection media for accessing disks. In terms of application data, most server clusters house it on disks in one of the common disk arrays. The data from an application stays on the server that manages that particular application.
Server clusters also handle security issues. Clusters are configured to protect data, maintain applications and services in the case of a failure on one of the servers, and enable configuration consistency over time.
Are there different kinds of server clusters?
Three types of server clusters connect to devices in different ways. Differences are based on the ways the cluster system (called a “node”) connects to the devices that store the cluster configuration and state data. This data must be stored so that each active node can get the information even if one or more nodes are failing. The information is housed on the “quorum resource,” which encompasses a set of cluster configuration information and records of changes made to the configuration. After a failure, a node coming online uses the quorum resource to discover the most recent system configuration changes.
Why does a business need a server cluster?
Data flow and security are crucial for any business. As a group of information-housing machines, a server cluster enables your business access to data and services even when an electrical or other failure occurs. To ensure that your data and applications are highly available, an organization needs a server cluster.