Re: Session distribution on 9i RAC

Steffen Roegner wrote:

> Howdy,
>
> We have a 4-node 9.2.0.4 RAC on Red Hat Ent. Linux 3 running. We want to
> use load balancing for users and a dedicated node for nightly batch
> processing. Our users tnsnames.ora looks like this:
>
> USERS =
> (DESCRIPTION =
> (ADDRESS_LIST =
> (ADDRESS = (PROTOCOL = TCP)(HOST = node1)(PORT = 1521))
> (ADDRESS = (PROTOCOL = TCP)(HOST = node2)(PORT = 1521))
> (ADDRESS = (PROTOCOL = TCP)(HOST = node3)(PORT = 1521))
> (LOAD_BALANCE = on)
> (FAILOVER = on)
> )
> (CONNECT_DATA =
> (SERVICE_NAME = cluster.domain.de)
> (FAILOVER_MODE =
> (TYPE = session)
> (METHOD = basic)
> )
> )
> )
>
> Since the users connect via the service_name, they will also get
> sessions on the last, fourth node which is not even mentioned in the
> address list which prevents me from setting things like a really big
> sort_area_size for this node.
>
> How can I prevent the users from being connected to the 4th node?

You can't. You're trying to do a 'spare nodes' configuration when you have more than 2 nodes, and that's not do-able in a nice and easy way. (In a 2-node RAC, you can set active_instance_count=1 to give yourself an active node and a spare. You can't set that parameter to 3 however!).

The only thing you can do is to 'hide' the fourth node from the users. That simply means making sure it hasn't registered itself with any of the three listeners you mention in the ADDRESS_LIST section of your tnsnames. You will want to remove entries that fourth instance may have in the spfile init.ora for REMOTE_LISTENER.

In other words, it all comes down to network configuration.

Regards
HJR Received on Fri Aug 13 2004 - 07:19:44 CDT