# Create Coherence clusters

Coherence clusters enable applications to share data management and caching services among server instances and clusters hosting the applications that need access to them.

Configure cluster properties and then target Coherence clusters to WebLogic Server instances or clusters in the domain.

To create Coherence clusters:

1. If you have not already done so, in the Change Center of the Administration Console, click Lock & Edit (see Use the Change Center).
2. In the left pane of the Console, expand Environment and select Coherence Clusters.

   The Summary of Coherence Clusters page displays the Coherence cluster configurations that have been created in this domain.

3. Click New.
4. On the Configuration: General page, adjust the following Coherence cluster properties values, if needed:
   1. Name: The name of this Coherence cluster configuration.
   2. Use a Custom Cluster Configuration File: Select whether to configure this cluster using an external custom configuration file and click Next.

      File Path: Provide the file path location of configuration file. The file must be present locally on the Administration Server. Click Next to select targets for the Coherence cluster.

   3. Clustering Mode: Select either unicast or multicast and specify the related settings.
   4. Unicast Listen Address: The IP address for the cluster unicast listener.
   5. Unicast Listen Port: The port for the cluster unicast listener. Valid values are between 0 and 65535.
   6. Unicast Port Auto Adjust: Specifies whether the unicast port will be automatically incremented if the port cannot be bound because it is already in use.
   7. Multicast Listen Address: The IP address for the cluster multicast listener.
   8. Multicast Listen Port: The multicast port used by cluster members to communicate with each other. Valid values are between 1 and 65535.
5. Click Next to select targets for the Coherence cluster or click Finish.
6. Optionally, select WebLogic Server instances or clusters on which this cluster configuration is accessible and click Finish.
   The new cluster configuration appears in the Coherence Clusters table.

   Note: All Coherence changes require a restart.

7. To activate these changes, in the Change Center of the Administration Console, click Activate Changes.
   Not all changes take effect immediately—some require a restart (see Use the Change Center).