关于REMOTE_LISTENER

问题：
remote_listener设置为LISTENERS_MDM,但是未在listener.ora中叨叨LISTENERS_MDM的配置。
SQL> show parameter list

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
remote_listener string LISTENERS_MDM
[oracle@RACC01 admin]$ pwd
/oracle/app/11gR1/db/network/admin
[oracle@RACC01 admin]$ cat listener.ora
# listener.ora.racc01 Network Configuration File: /oracle/app/11gR1/db/network/admin/listener.ora.racc01
# Generated by Oracle configuration tools.

LISTENER_RACC01 =
 (DESCRIPTION_LIST =
 (DESCRIPTION =
 (ADDRESS_LIST =
 (ADDRESS = (PROTOCOL = TCP)(HOST = RACC01-vip)(PORT = 1521)(IP = FIRST))
 )
 (ADDRESS_LIST =
 (ADDRESS = (PROTOCOL = TCP)(HOST = xxx)(PORT = 1521)(IP = FIRST))
 )
 (ADDRESS_LIST =
 (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))
 )
 )
 )


分析：
《Oracle database references》对REMOTE_LISTENER给出的解释：
REMOTE_LISTENER specifies a network name that resolves to an address or address list of Oracle Net remote listeners (that is, listeners that are not running on the same machine as this instance). The address or address list is specified in the TNSNAMES.ORA file or other address repository as configured for your system.
10.4.3 Registering Information with a Remote Listener
REMOTE_LISTENER是用来指定远程的监听地址，可以被本地监听redirect过去的（通常用于RAC环境），这个参数在tnsnames.ora中配置。
参考《Net Services Administrator's Guide》：
A remote listener is a listener residing on one computer that redirects connections to a database instance on another computer. Remote listeners are typically used in an Oracle Real Application Clusters (Oracle RAC) environment. You can configure registration to remote listeners, such as in the case of Oracle RAC, for dedicated server or shared server environments.
10.4.3.1 Registering Information with a Remote Listener in a Dedicated Server Environment
In a dedicated server environment, you must enable the PMON background process to register with a remote listener. You achieve this goal by configuring the REMOTE_LISTENER parameter in the initialization parameter file. The syntax of the REMOTE_LISTENER initialization parameter is as follows:
 REMOTE_LISTENER=listener_alias
listener_alias is resolved to the listener protocol addresses through a naming method such as a tnsnames.ora file on the database host.
To dynamically update the REMOTE_LISTENER initialization parameter, use the SQL statement ALTER SYSTEM SET. If you set the parameter to null with the statement that follows, then PMON de-registers information with the remote listener with which it had previously registered information, as in the following example:
 ALTER SYSTEM SET REMOTE_LISTENER=''
See Also:
 Oracle Database SQL Language Reference for further information about the ALTER SYSTEM SET statement
 To register information with a remote listener in a dedicated server environment:
 1.
On the host where the remote listener resides, configure the listener.ora file with the protocol addresses of the remote listener.
For example, assume that a remote listener listens on port 1521 on host sales2-server.
2.
On the database to which you want requests to be redirected, set the REMOTE_LISTENER parameter in the database initialization parameter file to the alias of the remote listener.
 
For example, suppose that a database resides on host sales1-server. To redirect requests to the database on sales1-server, you can set the REMOTE_LISTENER parameter in the initialization file for the database on host sales1-server as follows:
 REMOTE_LISTENER=listener_sales2
 3.
Resolve the listener name alias for the REMOTE_LISTENER setting through a tnsnames.ora file on the database host.
For example, in the tnsnames.ora on sales1-server, you can resolve the remote listener alias listener_sales2 as follows:
 listener_sales2=
 (DESCRIPTION=
   (ADDRESS=(PROTOCOL=tcp)(HOST=sales2-server)(PORT=1521)))
See Also:
Documentation: http://docs.oracle.com/cd/B28359_01/network.111/b28316/listenercfg.htm#NETAG302