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.