If you are configuring a collector for Oracle RAC, you only need to configure one collector for the entire cluster. You can choose any node in the cluster to connect to, and the entire cluster is automatically detected.

If you have sub-collectors, it will disable automatic cluster discovery. 

When the Database Visibility collecter connects to the hostname or IP address defined in the collector configuration, it auto-discovers the RAC instance. Once a successful connection is made to a node within the RAC, then a query on GV$INSTANCE will be used to return the details of the other member nodes and to populate the Topology Window.

When monitoring Oracle RAC, the Controller displays the aggregate data for the entire cluster.

User Permissions for Oracle RAC

When you upgrade to 4.3, you may encounter the following error: Network access denied by access control list (ACL). You can resolve the error by enabling ACLs for the monitoring user.

begin
dbms_network_acl_admin.create_acl (
acl             => 'Resolve_Access.xml',      
description     => 'Resolve Network Access using UTL_INADDR', 
principal       => '<DBMON USER>',                                                    
is_grant        => TRUE,                     
privilege       => 'resolve',                
start_date      => null,                     
end_date        => null                      
);
commit;
end;
/

begin
dbms_network_acl_admin.assign_acl (
acl           => 'Resolve_Access.xml',
host          => '*',                                                   
lower_port    => null,                
upper_port    => null);               
commit;
end;
/