Creating Clusters

Before you create a cluster, the Enterprise Manager must connect to the realms that will form the cluster. For information about how to connect to realms, see Connecting to Multiple Realms.

If you cannot connect to a realm or you receive a 'Security Alert' message when you click the realm node, you should check if the realm is running, and check the permissions on the realm. If the realms to which you want to connect are running on different machines, you must ensure that all realm machines are given full permissions to connect to the other realms in the cluster. Each realm communicates with the other cluster realms by using its own connection. For more information about realm permissions, see About Realm ACL Permissions.

For example, assume that there are three realms that will form a cluster, and the subject of each connection has the format: realm-<realmname>@<ip_address>. Each realm subject must exist in the ACLs of the other realms, so the following realm subjects must be added to the ACL for each realm:

realm-realm1@10.140.1.1 realm-realm2@10.140.1.2 realm-realm3@10.140.1.3

The permissions given for each realm must be 'Access Realm'. Also, each realm must have a valid entry for the user@host that corresponds to the user that will create the cluster using the Enterprise Manager. The permissions for this user must be sufficient in order to create the cluster object. Temporarily, it is often better to give 'Full' privileges to the *@* default subject in order to facilitate setting up a realm and clusters.

When you create a cluster, you must either migrate or delete all local stores on any of the realms participating in the cluster.

To create a cluster in the Enterprise Manager

1. Right-click the Clusters node and select Create Cluster.
2. In the Create New Cluster dialog box, specify a name for the new cluster.
   Important: The Enterprise Manager does not support working with two clusters that have the same name.
3. Add cluster members by selecting realms from the Available Realms list. Click OK.
   Important: A cluster cannot contain two realm nodes with the same node name, even if their host names and port numbers are different.

   One of the selected realms becomes the master realm during the creation of the cluster. The master realm controls synchronizing the state between the other realms and acts as the authoritative source for this information.

4. Select whether to migrate local stores to cluster-wide stores or delete the local stores.
   Note: If the name of a local store is the same as the name of an existing cluster store, the cluster creation will fail due to a name clash.

The Enterprise Manager displays the new cluster and its realms in the Clusters node tree. When you select the new cluster node, you can monitor its state on the Cluster Summary tab. The tab shows the state of all cluster members and which realm is the current master.