localport=4100

The second value is remoteport, the port that ONS binds to on all interfaces for talking to other ONS daemons. An example of the remoteport configuration is the following:

remoteport=4200

The third value specifies nodes, a list of other ONS daemons to talk to. Node values are given as a comma-delimited list of either host names or IP addresses plus ports. Note that the port value that is given is the remote port that each ONS instance is listening on. In order to maintain an identical file on all nodes, thehost:port of the current ONS node can also be listed in the nodes list. It will be ignored when reading the list.

The nodes listed in the nodes line correspond to the individual nodes in the RAC instance. Listing the nodes ensures that the middle-tier node can communicate with the RAC nodes. At least one middle-tier node and one node in the RAC instance must be configured to see one another. As long as one node on each side is aware of the other, all nodes are visible. You need not list every single cluster and middle-tier node in the ONS config file of each Oracle RAC node. In particular, if one ONS config file cluster node is aware of the middle tier, then all nodes in the cluster are aware of it.

An example of the nodes configuration is the following:

nodes=myhost.example.com:4200,123.123.123.123:4200

There are also several optional values that can be provided in ons.config.The first optional value is a loglevel. This specifies the level of messages that should be logged by ONS. This value is an integer that ranges from 1, which indicates least messages logged, to 9, which indicates most messages logged. The default value is 3. The following is an example:

loglevel=3

The second optional value is a logfile name. This specifies a log file that ONS should use for logging messages. The default value for logfile is$ORACLE_HOME/opmn/logs/ons.log. The following is an example:

logfile=/private/oraclehome/opmn/logs/myons.log

The third optional value is a walletfile name. A wallet file is used by the Oracle Secure Sockets Layer (SSL) to store SSL certificates. If a wallet file is specified to ONS, it will use SSL when communicating with other ONS instances and require SSL certificate authentication from all ONS instances that try to connect to it. This means that if you want to turn on SSL for one ONS instance, then you must turn it on for all instances that are connected. This value should point to the directory where your ewallet.p12 file is located. The following is an example:

walletfile=/private/oraclehome/opmn/conf/ssl.wlt/default

One optional value is reserved for use on the server-side. useocr=on is used to tell ONS to store all Oracle RAC nodes and port numbers in Oracle Cluster Registry (OCR) instead of in the ONS configuration file. Do not use this option on the client-side.

The ons.config file allows blank lines and comments on lines that begin with the number sign (#).

Client-Side ONS Configuration

You can access the client-side ONS through ORACLE_HOME/opmn. On the client-side, there are two ways to set up ONS:

Remote ONS configuration

See Also:

ONS daemon on the client-side

Example 26-1 illustrates how a sample configuration file may look.

Example 26-1 Example of a Sample ons.config File