The elements of a cluster

An iSeries™ cluster is a collection of one or more systems or partitions that work together as a single system. Use this information to understand the elements and their relationship to each other.

• Cluster node
  A cluster node is an iSeries system or logical partition that is a member of a cluster.
• Cluster resource group
  A cluster resource group (CRG) is an i5/OS™ system object that is a set or grouping of cluster resources that are used to manage events that occur in a clustered environment. The cluster resource group describes a recovery domain and supplies the name of the cluster resource group exit program which gets called when certain cluster events occur.
• Cluster administrative domain
  A cluster administrative domain is used to manage resources that need to be maintained consistently across the nodes in a clustered environment.
• Monitored resources
  Monitored resources are types of system resources that can be managed by a cluster administrative domain. These resources are represented in the cluster administrative domain as monitored resource entries (MREs).
• Cluster resource group exit programs
  A cluster resource group exit program is called after a cluster-related event for a CRG occurs.
• Recovery domain
  A recovery domain is a subset of cluster nodes that are grouped together in a cluster resource group (CRG) for a common purpose such as performing a recovery action or synchronizing events.
• Cluster version
  A cluster version represents the level of function available on the cluster.
• Resilient resources
  Resilient resources are system resources, such as data, devices and applications, that are highly available if you have used clustering on your systems.
• Device domains
  A device domain is a subset of nodes in a cluster that share device resources. More specifically, nodes in a device domain can participate in a switching action for some collection of resilient device resources.