After configuring ONS, you start the ONS daemon with the onsctl command. It is the user's responsibility to make sure that an ONS daemon is running at all times.

Using the onsctl Command

After configuring, use ORACLE_HOME/opmn/bin/onsctl to start, stop, reconfigure, and monitor the ONS daemon. Table 26-1 is a summary of the commands thatonsctl supports.

Table 26-1 onsctl Commands

Server-Side ONS Configuration Using racgons

You can access the server-side ONS through ORA_CRS_HOME/opmn. You configure the server-side by using racgons to add the middle-tier node information to OCR. This command is found in ORA_CRS_HOME/bin/racgons. Before using racgons, you must edit ons.config to set useocr=on.

The middle-tier nodes should be configured in OCR, so that all nodes share the configuration, and no matter which Oracle RAC nodes are up they can communicate to the middle-tier. When running on a cluster, always configure the ONS hosts and ports not by using the ONS configuration files but usingracgons. The racgons command stores the ONS hosts and ports in OCR, where every node can see it. That way, you do not need to edit a file on every node to change the configuration, just run a single command on one of the cluster nodes.

The racogns command enables you to specify hosts and ports on one node, then propagate your changes among all nodes in a cluster. The command takes two forms:

racgons add_config hostname:port [hostname:port] [hostname:port] ...
racgons remove_config hostname[:port] [hostname:port] [hostname:port] ...

The add_config version adds the listed host name(s), the remove_config version removes them. Both commands propagate the changes among all instances in a cluster.

If multiple port numbers are configured for a host, the specified port number is removed from hostname. If only hostname is specified, all port numbers for that host are removed.

See Also:

Other Uses of racgons

You should run racgons whenever you add a new node to the cluster.

Remote ONS Subscription

The advantages of remote ONS subscription are the following:

Support for an All Java middle-tier stack

No ONS daemon needed on the client computer and, therefore, no need to manage this process

Simple configuration using the DataSource property

When using remote ONS subscription for Fast Connection Failover, the application invokes the following method on an OracleDataSource instance:

setONSConfiguration(String remoteONSConfig)

The remoteONSConfig parameter is a list of name and value pairs of the form name=value that are separated by a new line character (\n). name can be one ofnodes, walletfile, or walletpassword. This parameter should specify at least the nodes ONS configuration attribute, which is a list of host:port pairs, each pair separated by comma (,). The hosts and ports denote the remote ONS daemons available on the Oracle RAC nodes.

See Also: