A two-node cluster with a hot standby configuration
Consider a single DB2® UDB instance in a single partition environment, where two cluster nodes use shared volume groups.
In this configuration, either node can have access to the shared volume group that contains the DB2 instance home file systems. In this environment, DB2 is installed on both nodes; the DB2 software is not shared. The following diagram shows the architecture necessary to support this configuration:
The following figure displays a two-node cluster configuration with a DB2 instance.
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Assume that in this configuration, node A owns the DB2 instance, that is, node A owns the resource group containing the application controller for the DB2 instance.
The shared volume group(s) for the DB2 instance contain the DB2 instance home and any number of volume groups containing copies of the archive and transaction logs for this instance. As part of this configuration, a service IP label is configured for the DB2 instance to communicate with other application tiers.
You can expand this two-node configuration by adding additional nodes to the nodelist for the resource group containing the DB2 instance application controller. The additional nodes can then serve as takeover nodes for the monitored DB2 instance. The DB2 software for the monitored instance will not be running on these additional takeover nodes until the PowerHA® SystemMirror® resource group that owns the instance falls over to the takeover node.
In PowerHA SystemMirror Smart Assist for DB2, a node can own one or more DB2 instances; additional resource groups must be added to the cluster to manage each new DB2 instance, that is, each DB2 instance must be included in a separate resource group.