关键词： load balance (负载均衡) ， fail over (透明切换)

以Oracle10g 为例子，Linux AS4.5

以下是listener.ora , tnsnames.ora , spfile 中的几个配置。

ecsrac01$cat listener.ora
# listener.ora.ecsrac01 Network Configuration File: /u01/product/oracle/network/admin/listener.ora.ecsrac01
# Generated by Oracle configuration tools.

LISTENER_ECSRAC01 =
(DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = TCP)(HOST = ecsvip01)(PORT = 1521)(IP = FIRST))
      )
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = TCP)(HOST = 10.134.130.177)(PORT = 1521)(IP = FIRST))
      )
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))
      )
    )
)

ecsrac01$cat tnsnames.ora
# tnsnames.ora Network Configuration File: /u01/product/oracle/network/admin/tnsnames.ora
# Generated by Oracle configuration tools.

ECSDB2 =
(DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = ecsvip02)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = ecsdb)
      (INSTANCE_NAME = ecsdb2)
    )
)

ECSDB1 =
(DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = ecsvip01)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = ecsdb)
      (INSTANCE_NAME = ecsdb1)
    )
)

ECS =
(DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 10.134.130.170)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = ecsdb)
    )
)

ECSDB =
(DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = ecsvip01)(PORT = 1521))
    (ADDRESS = (PROTOCOL = TCP)(HOST = ecsvip02)(PORT = 1521))
    (LOAD_BALANCE = yes)
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = ecsdb)
     (FAILOVER_MODE =
       (TYPE = SELECT)
       (METHOD = BASIC)
       (RETRIES = 180)
       (DELAY = 5)
     )
    )
)

LISTENERS_ECSDB =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = ecsvip01)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = ecsvip02)(PORT = 1521))
)

LOCAL_ECSDB =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 10.134.130.177)(PORT = 1521))
)

SQL> show parameter list

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
local_listener                       string      LOCAL_ECSDB
remote_listener                      string      LISTENERS_ECSDB

------------------------------------------------------------------------------------------------------------------

客户端Load Balance，Failover 设置：

ECSDB =
(DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = ecsvip01)(PORT = 1521))
    (ADDRESS = (PROTOCOL = TCP)(HOST = ecsvip02)(PORT = 1521))
    (LOAD_BALANCE = yes)
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = ecsdb)
     (FAILOVER_MODE =
       (TYPE = SELECT)
       (METHOD = BASIC)
       (RETRIES = 180)
       (DELAY = 5)
     )
    )
)

--------------------------------------------------------------------------------------------------------------------

Server 端Load Balance，Failover 设置：

Server 端的tnsnames.ora 中包含有

LISTENERS_ECSDB =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = ecsvip01)(PORT = 1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = ecsvip02)(PORT = 1521))
)

然后remote_listener 设置为tnsnames.ora 中的这个监听设置即可。

SQL> show parameter list

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
local_listener                       string      LOCAL_ECSDB
remote_listener                      string      LISTENERS_ECSDB

Oracle9i, 10g, 11g 负载均衡(load balance)和Fail Over