在linux上连接oracle的程序在大量、密集操作数据库时发生如下错误:

Fatal NI connect error 12520, connecting to:

(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=s120205)(PORT=1521))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=orcl)(CID=(PROGRAM=sms_

support)(HOST=s120205)(USER=oracle))))

VERSION INFORMATION:

TNS for Linux: Version 10.2.0.1.0 - Production

TCP/IP NT Protocol Adapter for Linux: Version 10.2.0.1.0 - Production

Time: 07-5月 -2010 17:42:58

Tracing not turned on.

Tns error struct:

ns main err code: 12564

TNS-12564: TNS: 拒绝连接

ns secondary err code: 0

nt main err code: 0

nt secondary err code: 0

nt OS err code: 0

出现这个错误，在oracle的监听没有启动的情况下。重点排查lisnter.ora和tnsname.ora的配置。

比如tnsnames.ora文件：

ORCL =

(DESCRIPTION =

(ADDRESS = (PROTOCOL = TCP)(HOST = s120205)(PORT = 1521))

(CONNECT_DATA =

(SERVER = DEDICATED)

(SERVICE_NAME= orcl)

)

)

修改为

ORCL =

(DESCRIPTION =

(ADDRESS = (PROTOCOL = TCP)(HOST = s120205)(PORT = 1521))

(CONNECT_DATA =

(SERVER = DEDICATED)

(SID = orcl)

)

)

在没有监听异常的情况下查看/app/oracle/admin/orcl/bdump/alert_实例名.log日志。

比如出现表空间不足的情况下也可能出现这个问题..