ORA-12518 TNS:监听程序无法分发客户机连接的解决办法

环境：windows XP +Oracle 10g R2

一、listener文件中的GLOBAL_DBNAME ,SID_NAME可能与实例名称不符，修改后，重启listener.

二、专有服务器模式下processes值设的过小。

　　可通过以下方法解决：

1.cmd
2.sqlplus
3.connect sys/test as sysdba
4.查看会话数、processes、sessions

SQL> select count(*) from v$session;
         COUNT(*)
 
        ----------
           45

SQL> show parameter processes
    NAME                                 TYPE        VALUE
    db_writer_processes                  integer     1
    gcs_server_processes                 integer     0
    job_queue_processes                  integer     10
    log_archive_max_processes            integer     2
    processes                            integer     50
SQL> show parameter sessions
    NAME                                 TYPE        VALUE
    java_soft_sessionspace_limit         integer     0l
    icense_max_sessions                 integer     0
    license_sessions_warning             integer     0
    logmnr_max_persistent_sessions       integer     1
    sessions                             integer     60
    shared_server_sessions               integer

5.修改processes和sessions值:sessions=(1.1*process+5)

  SQL> alter system set processes=300 scope=spfile;
   系统已更改。
  SQL> alter system set sessions=335 scope=spfile;
     系统已更改。

　　6.重启数据库，使更改生效

　　（不过我没有重启）

三、共享模式下

1.show parameters dispatchers;

show parameters dispatchers;
NAME TYPE VALUE
dispatchers string (protocol=tcp)(service=oracle10xdb)
max_dispatchers integer

2.确定是否有足够的dispatchers

SQL> select name, (busy/(busy + idle)) "dispatcher busy rate" from v$dispatcher ; 
NAME dispatcher busy rate
---- --------------------
D000 .000121704
D001 .000042597
D002 .004935402 
如果超过50%，则需要考虑增加更多的dispatchers;

3.改变dispathchers:

SQL>alter system set dispatchers = '(protocol=tcp)(dispatchers=3)(service=oracle10xdb)';
system altered

四、PGA内存设置太小

注：该方法没试过。

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按照如上我的解决方案：

cmd调出命令行窗口

Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.

C:Documents and SettingsAdministrator>sqlplus /nolog

SQL*Plus: Release 10.2.0.1.0 - Production on 月 2月 20 13:45:30 2012

Copyright (c) 1982, 2005, Oracle. All rights reserved.

SQL> connect sys/test as sysdba
Was connected to an idle instance.
 
SQL> show parameters dispatchers;
ORA-01034: ORACLE not available
 
SQL> connect SYS/SYSADMIN as sysdba
Was connected to an idle instance.
 
SQL> select count(*) from v$session;
 
SQL> show parameter processes
 
SQL> alter system set processes=1000 scope=spfile;
 
SQL> alter system set sessions=1100 scope=spfile;
 
SQL> select  name, (busy/(busy + idle)) "dispatcher busy rate" from v$dispatcher ;

重新登录就可以了