TNS-12541: TNS:no listener , TNS-12542: TNS:address already in use
查看数据库监听状态不对
$ lsnrctl status
LSNRCTL for IBM/AIX RISC System/6000: Version 10.2.0.5.0 - Production on 05-NOV-2012 08:54:08
Copyright (c) 1991, 2010, Oracle. All rights reserved.
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=test)(PORT=1521)))
TNS-12541: TNS:no listener
TNS-12560: TNS:protocol adapter error
TNS-00511: No listener
IBM/AIX RISC System/6000 Error: 79: Connection refused
然后手动启动数据库报如下错误：
$ lsnrctl start
LSNRCTL for IBM/AIX RISC System/6000: Version 10.2.0.5.0 - Production on 05-NOV-2012 08:54:12
Copyright (c) 1991, 2010, Oracle. All rights reserved.
Starting /oracle/product/10.2.0/db_1/bin/tnslsnr: please wait...
TNSLSNR for IBM/AIX RISC System/6000: Version 10.2.0.5.0 - Production
System parameter file is /oracle/product/10.2.0/db_1/network/admin/listener.ora
Log messages written to /oracle/product/10.2.0/db_1/network/log/listener.log
Error listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=test)(PORT=1521)))
TNS-12542: TNS:address already in use
TNS-12560: TNS:protocol adapter error
TNS-00512: Address already in use
IBM/AIX RISC System/6000 Error: 67: Address already in use
Listener failed to start. See the error message(s) above...
/oracle/product/10.2.0/db_1/network/trace/listener.trc
明明监听没启动起，却说已经在运行了，后来终于找到原因，网上看到别人也碰到这个问题，说是HOSTS文件设置有问题，查看本机主机名和hosts文件，果然有问题，两个IP地址指向了同一个主机名，将一台主机删除后，再启动监听，一切OK。
用root用户进行修改：
# cat /etc/hosts
# Internet Address Hostname # Comments
# 192.9.200.1 net0sample # ethernet name/address
# 128.100.0.1 token0sample # token ring name/address
# 10.2.0.2 x25sample # x.25 name/address
# 2000:1:1:1:209:6bff:feee:2b7f ipv6sample # ipv6 name/address
127.0.0.1 loopback localhost # loopback (lo0) name/address
192.168.101.189 test
192.168.101.190 test
再次启动监听：
$ lsnrctl start
LSNRCTL for IBM/AIX RISC System/6000: Version 10.2.0.5.0 - Production on 05-NOV-2012 08:58:47
Copyright (c) 1991, 2010, Oracle. All rights reserved.
Starting /oracle/product/10.2.0/db_1/bin/tnslsnr: please wait...
TNSLSNR for IBM/AIX RISC System/6000: Version 10.2.0.5.0 - Production
System parameter file is /oracle/product/10.2.0/db_1/network/admin/listener.ora
Log messages written to /oracle/product/10.2.0/db_1/network/log/listener.log
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=test)(PORT=1521)))
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC0)))
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=test)(PORT=1521)))
STATUS of the LISTENER
------------------------
Alias LISTENER
Version TNSLSNR for IBM/AIX RISC System/6000: Version 10.2.0.5.0 - Production
Start Date 05-NOV-2012 08:58:49
Uptime 0 days 0 hr. 0 min. 0 sec
Trace Level off
Security ON: Local OS Authentication
SNMP ON
Listener Parameter File /oracle/product/10.2.0/db_1/network/admin/listener.ora
Listener Log File /oracle/product/10.2.0/db_1/network/log/listener.log
Listening Endpoints Summary...
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=test)(PORT=1521)))
(DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC0)))
Services Summary...
Service "PLSExtProc" has 1 instance(s).
Instance "PLSExtProc", status UNKNOWN, has 1 handler(s) for this service...
The command completed successfully
总结：/etc/hosts文件设置很重要，这里设置不正确，很多地方都要出错，特别是RAC，会报很多奇怪的错误，配置的时候要多注意。
REF: