TNSNAMES.ORA 配置

SQLNET.AUTHENTICATION_SERVICES= (NTS)——这个表示采用os认证，在数据库服务器上，可以利用sqlplus “/ as sysdba”。一般这个配置在windows上是ok的，在unix环境下可能会有问题，一般在unix下可以去掉这个配置。

NAMES.DIRECTORY_PATH= (TNSNAMES, HOSTNAME, ONAMES)——表示将首先利用tnsnames进行解析；如果tnsnames解析不到，将使用hostname解析；如果hostname解析不 到，将采用onames进行解析。

被注释掉的NAMES.DEFAULT_DOMAIN = us.oracle.com——表示采用默认的domain name为us.oracle.com，在tnsnames.ora中如果配置对应的解析，如果原来的别名oralocal，那么，当启用这个参数后，在 tnsnames中的配置要改成oralocal.us.oracle.com。在使用tnsping时或者sqlplus登录时，只需写前面的别名，系 统会自动加上后面的domain name来进行解析。

检查完毕sqlnet.ora，一般都会发现是使用tnsname来解析别名的，那么，tnsnames.ora中可以有哪些配置种类呢？

# TNSNAMES.ORA Network Configuration File: $ORACLE_HOME/NETWORK/ADMIN/tnsnames.ora
# Generated by Oracle configuration tools.


###### 一般的配置 ##################################
ORALOCAL =
  ( DESCRIPTION =
    ( ADDRESS_LIST =
      ( ADDRESS = ( PROTOCOL = TCP )( HOST = 127.0.0.1 )( PORT = 1521 ))
    )
    ( CONNECT_DATA =
      ( SERVER = DEDICATED )
      ( SERVICE_NAME = oralocal )
    )
  )


###### 这样也行，用SID=oralocal ###########################
ORALOCAL_2 =
  ( DESCRIPTION =
    ( ADDRESS_LIST =
      ( ADDRESS = ( PROTOCOL = TCP )( HOST = 127.0.0.1 )( PORT = 1521 ))
    )
    ( CONNECT_DATA =
      ( SERVER = DEDICATED )
      ( SID = oralocal )
    )

###### RAC的配置(3节点rac) ###############################
ORALOCAL =
  ( DESCRIPTION =
  ( load_balance = yes )
  ( failover = on )
    ( ADDRESS_LIST =
      ( ADDRESS = ( PROTOCOL = TCP )( HOST = 192.168.1.1 )( PORT = 1521 ))
      ( ADDRESS = ( PROTOCOL = TCP )( HOST = 192.168.1.2 )( PORT = 1521 ))
      ( ADDRESS = ( PROTOCOL = TCP )( HOST = 192.168.1.3 )( PORT = 1521 ))   
    )
    ( CONNECT_DATA =
        ( SERVICE_NAME = oralocal )
        ( SERVER = DEDICATED )
        ( failover_mode = ( type = select )( method = basic )( retries = 20 )( delay = 20 ))
    )
  )
 
ORALOCAL_NODE1 =
   ( DESCRIPTION =
     ( ADDRESS_LIST =
       ( ADDRESS = ( PROTOCOL = TCP )( HOST = 192.168.1.1 )( PORT = 1521 ))
       )
       ( CONNECT_DATA =
         ( SERVICE_NAME = oralocal )
         ( INSTANCE_NAME = oralocal_node1 )
       )
   )


ORALOCAL_NODE2 =
   ( DESCRIPTION =
     ( ADDRESS_LIST =
       ( ADDRESS = ( PROTOCOL = TCP )( HOST = 192.168.1.2 )( PORT = 1521 ))
       )
       ( CONNECT_DATA =
         ( SERVICE_NAME = oralocal )
         ( INSTANCE_NAME = oralocal_node2 )
       )
   )
  

ORALOCAL_NODE3 =
   ( DESCRIPTION =
     ( ADDRESS_LIST =
       ( ADDRESS = ( PROTOCOL = TCP )( HOST = 192.168.1.3 )( PORT = 1521 ))
       )
       ( CONNECT_DATA =
         ( SERVICE_NAME = oralocal )
         ( INSTANCE_NAME = oralocal_node3 )
       )
   )


  )


###### DATA GUARD配置（primary库和standby库都需要配置）##############
standby =
  ( DESCRIPTION =
    ( ADDRESS_LIST =
      ( ADDRESS = ( PROTOCOL = TCP )( HOST = 192.168.2.2 )( PORT = 1521 ))
        )
    ( CONNECT_DATA =
          ( SERVER = DEDICATED )
          ( SERVICE_NAME = oralocal )
      )
  )

primary =
  ( DESCRIPTION =
    ( ADDRESS_LIST =
      ( ADDRESS = ( PROTOCOL = TCP )( HOST = 192.168.2.1 )( PORT = 1521 ))
        )
    ( CONNECT_DATA =
          ( SERVER = DEDICATED )
          ( SERVICE_NAME = oralocal )
      )
  )

另外需要注意的2点情况：
（1）如果tnsnames中的service_name配置错误，配置成了instance_name了，这个时候会发生tnsping能通，但是 sqlplus连接不上的奇怪情况。报错ORA-12514: TNS:listener could not resolve SERVICE_NAME given in connect descriptor。这个时候查错的时候，需要检查对应的service_name。
（2）如果远程数据库是rac，而且本地客户端端远程数据库处于不同的网段，通过公网链接，rac对外的ip映射只有一个，即只映射到一个节点。请注意在 客户端配置tnsnames的时候按照单机的情况来配置。呵呵，dba不仅仅要学习oracle，了解一些网络的知识，特别是自己系统的网络架构，也是需 要的。