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It helps to share a common terminology for concepts used in this redbook. The high availability field often uses multiple terms for the same concept, but in this redbook, we adhere to conventions set by International Business Machines Corporation whenever possible.
Cluster | This refers to a group of servers configured for high availability of one or more applications. |
Node | This refers to a single server in a cluster. |
Primary | This refers to a node that initially runs an application when a cluster is started. |
Backup | This refers to one or more nodes that are designated as the servers an application will be migrated to if the application's primary node fails. |
Joining | This refers to the process of a node announcing its availability to the cluster. |
Fallover | This refers to the process of a backup node taking over an application from a failed primary node. |
Reintegration | This refers to the process of a failed primary node that was repaired rejoining a cluster. Note that the primary node's application does not necessarily have to migrate back to the primary node. See fallback. |
Fallback | This refers to the process of migrating an application from a backup node to a primary node. Note that the primary node does not have to be the original primary node (for example, it can be a new node that joins the cluster). |
For more terms commonly used when configuring high availability, refer to High Availability Cluster Multi-Processing for AIX Master Glossary, Version 5.1, SC23-4867.
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