IT: Cluster/Clustering (Definitions)

"Technology that enables you to create a hot spare. That is a server that is actually running and can take over immediately. This technology enables you to mirror an entire server to another computer." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"The use of multiple computers to provide increased reliability, capacity, and management capabilities." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"Grouping data together on the same disk page to improve retrieval performance." (Jan L Harrington, "Relational Database Dessign: Clearly Explained" 2nd Ed., 2002)

"Any collection of distinct computers that are connected and used as a parallel computer, or to form a redundant system for higher availability. The computers in a cluster are not specialized to cluster computing and could, in principle, be used in isolation as standalone computers. In other words, the components making up the cluster, both the computers and the networks connecting them, are not custom-built for use in the cluster." (Beverly A Sanders, "Patterns for Parallel Programming", 2004)

"Connecting two or more computers in such a way that they behave like a single computer to an application or client. Clustering is used for parallel processing, load balancing, and fault tolerance." (Allan Hirt et al, "Microsoft SQL Server 2000 High Availability", 2004)

[server cluster:] "The type of Windows Clustering that provides availability only. It is a collection of nodes that allow resources to be failed over to another node in the event of a problem. SQL Server 2000 failover clustering is installed and configured on top of a server cluster." (Allan Hirt et al, "Microsoft SQL Server 2000 High Availability", 2004)

"A group of computers linked via a LAN and working together to form the equivalent of a single computer." (Linda Volonino & Efraim Turban, "Information Technology for Management" 8th Ed., 2011)

[failover cluster:] "A group of servers that are in one location and that are networked together for the purpose of providing live backup in case one of the servers fails." (Microsoft, "SQL Server 2012 Glossary", 2012)

"A set of computers with distributed memory communicating over a high-speed interconnect. The individual computers are often called nodes." (Michael McCool et al, "Structured Parallel Programming", 2012)

"A group of servers connected by a network and configured in such a way that if the primary server fails, a secondary server takes over." (IBM, "Informix Servers 12.1", 2014)

"A cluster is a set of servers configured to function together. Servers sometimes have differentiated functions and sometimes they do not." (Dan Sullivan, "NoSQL for Mere Mortals®", 2015)

"A collection of complete systems that work together to provide a single, unified computing capability." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

[failover clustering:] "A network of two or more interconnected servers that redirects an overloaded or failed resource to maintain system availability." (Microsoft Technet)