二、SQL*NET 配置
在创建备库前，要确认两台服务器的数据库之间能通信，如果我们要用 RMAN 的 duplicate from active database 命令创建备库的话。我们需要配置监听和 TNS 名。
虽然数据库会自动注册监听，但如果要使用 RMAN的 duplicate 命令创建备库，备库必须首先处于 NOMOUNT 状态。在 NOMOUNT 状态下，数据库实例不会自动注册监听，你必须配置静态监听。另外必须要注意的一点是，NOMOUNT 状态下的数据库必须使用专用模式(dedicated server)连接。
两台服务器上的 TNS 名字文件必须配置好，让主备库能用 LOG_ARCHIVE_DEST_N 和 FAL_SERVER 参数（稍后会介绍这些参数）中的服务名(Service Names）找到对方。具体配置应类似下例。
修改主备库listener.ora，tnsnames.ora文件如下，备库根据自身情况修改
SDU=32767 为DG优化网络传输参数
修改主库监听配置$Oracle_HOME/network/admin/listener.ora
********************* listener.ora *******************************
# listener.ora Network Configuration File:/data/oracle/app/oracle/product/11.2.0/dbhome_1/network/admin/listener.ora
# Generated by Oracle configuration tools.
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(SDU=32767)
(GLOBAL_DBNAME = orcl_primary)
(ORACLE_HOME =/data/oracle/app/oracle/product/11.2.0/dbhome_1)
(SID_NAME = orcl)
)
)
LISTENER =
(DESCRIPTION =
(ADDRESS = (PROTOCOL =TCP)(HOST = 192.168.10.205)(PORT = 1521))
)
ADR_BASE_LISTENER =/data/oracle/app/oracle
*********************listener.ora *******************************
修改备库监听配置同上，除了HOST地址更改为备库服务器地址
********************* listener.ora *******************************
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(SDU=32767)
(GLOBAL_DBNAME = orcl_standby)
(ORACLE_HOME =/data/oracle/app/oracle/product/11.2.0/dbhome_1)
(SID_NAME = orcl)
)
)
LISTENER =
(DESCRIPTION =
(ADDRESS = (PROTOCOL =TCP)(HOST = 192.168.10.206)(PORT = 1521))
)
ADR_BASE_LISTENER =/data/oracle/app/oracle
*********************listener.ora *******************************
修改配置tnsname.ora文件（主、备库都都为如下）
说明：orcl_primary是主库的服务名，orcl_standby是备库的服务名。
$ vi$ORACLE_HOME/network/admin/tnsnames.ora
******************* tnsnames.ora ****************************
# listener.ora Network Configuration File:/data/oracle/app/oracle/product/11.2.0/dbhome_1/network/admin/listener.ora
# Generated by Oracle configuration tools.
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(SDU=32767)
(GLOBAL_DBNAME = orcl_primary)
(ORACLE_HOME =/data/oracle/app/oracle/product/11.2.0/dbhome_1)
(SID_NAME = orcl)
)
)
LISTENER =
(DESCRIPTION =
(ADDRESS = (PROTOCOL =TCP)(HOST = 192.168.10.205)(PORT = 1521))
)
ADR_BASE_LISTENER =/data/oracle/app/oracle
[oracle@oradb205 admin]$ cat tnsnames.ora
orcl_primary =
(DESCRIPTION =
(SDU=32767)
(ADDRESS = (PROTOCOL =TCP)(HOST = 192.168.10.205)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = orcl_primary)
)
)
orcl_standby =
(DESCRIPTION =
(SDU=32767)
(ADDRESS = (PROTOCOL =TCP)(HOST = 192.168.10.206)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = orcl_standby)
#(UR = A)
)
)
for_db =
(DESCRIPTION =
(ADDRESS = (PROTOCOL =TCP)(HOST = 192.168.10.205)(PORT = 1521))
)
*******************tnsnames.ora ****************************
测试服务名连通性：
$ tnsping orcl_primary
$ tnsping orcl_standby
现在主备库之间依旧可以互相通信了