问题：一台机器同时装两套数据库时（实例名o8161,o8151)，无法同时启动两个listener，当启动第二个listener时，显示错误。

　　$ lsnrctl start

　　LSNRCTL for IBM/AIX RISC System/6000: Version 8.1.5.0.0 - Production on 14-SEP-00 09:25:17

　　(c) Copyright 1998 Oracle Corporation. All rights reserved.

　　TNS-01106: Listener using listener name LISTENER has already been started

　　$ oerr tns 1106
　　01106, 00000, "Listener using listener name %s has already been started"
　　// *Cause: Another listener is already listening on one of the ADDRESSes
　　// specified.
　　// *Action: Shutdown the previous listener specified by the listener name
　　// before starting this one.

　　问题产生原因：
　　两个实例的LISTENER.ORA中IPC协议的KEY是相同，而一个系统中KEY必须是唯一的.

　　解决办法：
　　修改key的值即可。修改后的文件信息：

　　o8161实例：（没有修改)

　　# LISTENER.ORA Configuration File:/oracle/dbs/opstemp/szpcac1/network/admin/listener.ora
　　# Generated by Oracle configuration tools.

　　LISTENER =
　　(DESCRIPTION_LIST =
　　(DESCRIPTION =
　　(ADDRESS_LIST =
　　(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
　　)
　　(ADDRESS_LIST =
　　(ADDRESS = (PROTOCOL = TCP)(HOST = loopback)(PORT = 1521))
　　)
　　)
　　(DESCRIPTION =
　　(PROTOCOL_STACK =
　　(PRESENTATION = GIOP)
　　(SESSION = RAW)
　　)
　　(ADDRESS = (PROTOCOL = TCP)(HOST = loopback)(PORT = 2481))
　　)
　　)

　　SID_LIST_LISTENER =
　　(SID_LIST =
　　(SID_DESC =
　　(SID_NAME = PLSExtProc)
　　(ORACLE_HOME = /oracle)
　　(PROGRAM = extproc)
　　)
　　(SID_DESC =
　　(ORACLE_HOME = /oracle)
　　(SID_NAME = o8161)
　　)
　　)

　　08151实例：（经过修改)

　　# LISTENER.ORA Configuration File:/ora815/network/admin/listener.ora
　　# Generated by Oracle Net8 Assistant

　　LISTENER =
　　(DESCRIPTION_LIST =
　　(DESCRIPTION =
　　(ADDRESS_LIST =
　　(ADDRESS = (PROTOCOL = IPC)(KEY = TESTo815))
　　)
　　(ADDRESS_LIST =
　　(ADDRESS = (PROTOCOL = TCP)(HOST = loopback)(PORT = 1526))
　　)
　　)
　　)

　　SID_LIST_LISTENER =
　　(SID_LIST =
　　(SID_DESC =
　　(SID_NAME = ora8151)
　　(ORACLE_HOME = /ora815)
　　(PROGRAM = extproc)
　　)
　　)