Clustering

A cluster is a component of Db2® Mirror that is required for independent auxiliary storage pool (IASP) management, maintaining quorum data, and advanced node failure detection.

The following figure is an example of a Db2 Mirror cluster.

Db2 Mirror nodes can be added to a new or existing cluster.

Db2 Mirror requires the cluster version to be 9 or higher.

For more information, see SET_MIRROR_CLUSTER procedure and Planning clusters.

Cluster monitors

Cluster monitors are used by Db2 Mirror for advanced node failure detection when communication between the nodes has been unexpectedly lost. Cluster monitors provide the capability to query the Hardware Management Console (HMC) for the status of the other node. It is required to configure cluster monitors on the Db2 Mirror nodes.

In order to configure a cluster monitor, you must have a digital certificate from the HMC. See Digital certificate for cluster monitors for details.

Note: If cluster monitors are not configured and the primary node fails, the secondary node will not be able to automatically take over as the primary node.

Note: If cluster monitors are not configured and the IFS server node fails, the client node will not mutate to become the new server node.

Quorum data

Quorum data is cluster-wide data that is stored on all the nodes in the cluster. It is used by Db2 Mirror to verify status and information about the nodes when they are unable to communicate.

Adding a third node to the cluster, referred to as the quorum node, is recommended because it helps ensure the reliability of the quorum data.