tnsname之双IP failover问题
如果是dataguard,经常在应用端配置双IP，以便在数据库切换时，应用端不用作任何的改变。但在ORACLE 9i里，这种方式配置的tnsname,存在着如下的问题。当需要对第一个IP进行停机维护时，即第一个IP不存在时，需要很长一段时间客户端才能failover到第二个IP上，创建新的连接.这个问题，也曾经导致过一次生产库事故。
在oracle 9i里，进行如下的测试:
引用:
db_tns =
(DESCRIPTION =
(failover = on )
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.168.100)(PORT = 1521)) --第一个IP不存在
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.168.120)(PORT = 1521)) --这个IP此时是主库
)
(CONNECT_DATA =
(SERVER = DEDICATED)
(SID = test)
)
)
db_stb:/u01/oracle/product/9.2/network/admin>$tnsping db_tns
TNS Ping Utility for IBM/AIX RISC System/6000: Version 9.2.0.6.0 - Production on 04-AUG-2008 13:59:02
Copyright (c) 1997 Oracle Corporation. All rights reserved.
Used parameter files:
/u01/oracle/product/9.2/network/admin/sqlnet.ora
Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (failover = on) (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.168.100)(PORT = 1521)) (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.168.120)(PORT = 1521))) (CONNECT_DATA = (SERVER = DEDICATED) (SID = test)))
OK (76380 msec) --这里总共花了76秒钟
