| Concepts and terminology
Before delving into the design details we first introduce some concepts and terms used throughout the paper. Members of a cluster are referred to as nodes or systems and the terms are used interchangeably. The Cluster Service is the collection of software on each node that manages all cluster specific activity. A Resource is the canonical item managed by the Cluster Service, which sees all resources as identical opaque objects. Resources may include physical hardware devices such as disk drives and network cards, or logical items such as logical disk volumes, TCP/IP addresses, entire applications, and databases. A resource is said to be on-line on a node when it is providing its service on that specific node. A group is a collection of resources to be managed as a single unit. Usually a group contains all of the elements needed to run a specific application, and for client systems to connect to the service provided by the application. Groups allow an administrator to combine resources into larger logical units and manage them as a unit. Operations performed on a group affect all resources contained within that Group.
|
