Preferred nodes in RAC setup

In Oracle Real Application Clusters (RAC) setup, you can specify the preferred nodes on which the backup operation will be performed. If you do not specify the preferred node, SnapCenter automatically assigns a node as the preferred node and backup is created on that node.

The preferred nodes might be one or all the cluster nodes where the RAC database instances are present. The backup operation will be triggered only on these preferred nodes in the order of the preference.

For example, the RAC database cdbrac has three instances, namely cdbrac1 on node1, cdbrac2 on node2, and cdbrac3 on node3. The node1 and node2 are configured to be the preferred nodes with node2 being the first preference and node1 as the second preference. When you perform a backup operation, the operation will be first attempted on node2 because it is the first preferred node. If node2 is not in the state to back up which could be due to multiple reasons such as the plug-in agent is not running on the host, or the database instance on the host is not in the required state for the specified backup type; then the operation will be attempted on node1. The node3 will not be used for backup because it is not on the list of preferred nodes.

For information about how to specify the preferred nodes, see the administrative information.

Performing administrative tasks with SnapCenter

Required database state

The RAC database instances on the preferred nodes must be in the required state for the backup to complete successfully.