ORA12514遇到了怎么排查问题出在哪

今天使用SQL Developer连接一台测试服务器数据库（ORACLE 11g）时，遇到了“ORA-12514, TNS:listener does not currently know of service requested in connect descriptor”错误，具体提示如下所示：

执行请求的操作时遇到错误:

Listener refused the connection with the following error:

ORA-12514, TNS:listener does not currently know of service requested in connect descriptor

供应商代码 12514

Step 1： 首先检查客户端的tnsnames.ora里面的host、port、service_name等是否正确

myvm =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 10.20.57.15)(PORT = 1521))
    )
    (CONNECT_DATA =
       (SERVER = SHARED)
      (SERVICE_NAME = gsp.localdomain)

    )
  )

逐一仔细检查过后发现这些配置都是正确的。 其实前几天还是正常来的。测试服务器和tnsnames.ora都没有改动过。所以我们继续后面排查。

Step 2：检查确认数据库实例是否启动。

SQL> select status from v$instance;

STATUS
------------
OPEN

SQL>

如上所示，数据库实例正常，并没有关闭。当数据库实例异常关闭，也会出现ORA-12514错误，如下所示（如果我关闭一数据库实例，然后使用SQL*Plus测试连接数据库就会遇到这个错误）：

C:\Users>sqlplus system/123456@mydb

SQL*Plus: Release 11.2.0.1.0 Production on 星期三 4月 12 11:56

Copyright (c) 1982, 2010, Oracle.  All rights reserved.

ERROR:
ORA-12514: TNS: 监听程序当前无法识别连接描述符中请求的服务

Step 3：检查网络是否正常，tnsping能否ping通

如下所示，ping 和tnsping 均都正常

监听服务也正常，没有问题

[oracle@DB-Server admin]$ lsnrctl status

LSNRCTL for Linux: Version 11.2.0.1.0 - Production on 12-APR-2017 10:36:40

Copyright (c) 1991, 2009, Oracle.  All rights reserved.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1521)))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 11.2.0.1.0 - Production
Start Date                12-APR-2017 10:31:20
Uptime                    0 days 0 hr. 5 min. 20 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Parameter File   /u01/app/oracle/product/11.1.0/dbhome_1/network/admin/listener.ora
Listener Log File         /u01/app/oracle/diag/tnslsnr/DB-Server/listener/alert/log.xml
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1521)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=DB-Server.localdomain)(PORT=1521)))
The listener supports no services
The command completed successfully

Step 4：检查$ORACLE_BASE/diag/tnslsnr/DB-Server/listener/alert下的日志，发现host_addr为10.20.34.76，实际IP地址不是这个。因为监听文件里面我使用的hostname DB-Server.localdomain，所以赶紧检查/etc/hosts的配置

[root@DB-Server ~]# ifconfig
eth0      Link encap:Ethernet  HWaddr B0:83:FE:55:32:E5
          inet addr:10.20.57.15  Bcast:10.20.57.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2363981 errors:0 dropped:0 overruns:0 frame:0
          TX packets:180048 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:225925147 (215.4 MiB)  TX bytes:14349633 (13.6 MiB)
          Interrupt:233 Base address:0x4000

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:3692 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3692 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:2982961 (2.8 MiB)  TX bytes:2982961 (2.8 MiB)

[root@DB-Server ~]# more /etc/hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
10.20.34.76        DB-Server.localdomain DB-Server
127.0.0.1               localhost.localdomain localhost
::1             localhost6.localdomain6 localhost6
[root@DB-Server ~]#

果然发现/etc/hosts下配置为10.20.34.76， 具体原因是因为IT部门调换办公室，从三楼撤到二楼，将这台PC搬下来后，服务器IP地址变化了，修改/etc/hosts，然后重启监听服务，问题解决。