关于RAC failover的实践

RAC Failover 实验

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本文记录了一次针对 Oracle RAC 系统 failover 的实验过程。通过切断一个节点的电源来模拟故障转移，验证了 SQL*Plus 会话是否需要重新连接。结果显示，会话自动切换到了另一个活动节点，无需手动干预。

关于之前RAC的failover同事们都有一个猜想，failover需要重新连接

今天实践了一下
例如：
2 nodes RAC
rac1
rac2

tnsnames.ora


RAC =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 10.189.128.44)(PORT = 1521))
    (ADDRESS = (PROTOCOL = TCP)(HOST = 10.189.128.45)(PORT = 1521))
    (LOAD_BALANCE = yes)
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = rac)
      (FAILOVER_MODE =
        (TYPE = SELECT)
        (METHOD = BASIC)
        (RETRIES = 180)
        (DELAY = 5)
      )
    )
  )

在cmd中打开sqlplus：


C:\Documents and Settings\guoyanxi>sqlplus system/manager1@rac

SQL*Plus: Release 10.1.0.2.0 - Production on 星期五 5月 21 08:52:17 2010

Copyright (c) 1982, 2004, Oracle.  All rights reserved.


連線到:
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production
With the Partitioning, Real Application Clusters, OLAP, Data Mining
and Real Application Testing options

SQL> select instance_name from v$instance;

INSTANCE_NAME
--------------------------------
rac2

目前连接的是rac2
server中的状态：


oracle@rac1: /home/oracle> crs_stat -t
Name           Type           Target    State     Host        
------------------------------------------------------------
ora.rac.db     application    ONLINE    ONLINE    rac1        
ora....c1.inst application    ONLINE    ONLINE    rac1        
ora....c2.inst application    ONLINE    ONLINE    rac2        
ora....C1.lsnr application    ONLINE    ONLINE    rac1        
ora.rac1.gsd   application    ONLINE    ONLINE    rac1        
ora.rac1.ons   application    ONLINE    ONLINE    rac1        
ora.rac1.vip   application    ONLINE    ONLINE    rac1        
ora....C2.lsnr application    ONLINE    ONLINE    rac2        
ora.rac2.gsd   application    ONLINE    ONLINE    rac2        
ora.rac2.ons   application    ONLINE    ONLINE    rac2        
ora.rac2.vip   application    ONLINE    ONLINE    rac2        
oracle@rac1: /home/oracle>

然后断开rac2的电源：


oracle@rac1: /home/oracle> crs_stat -t
Name           Type           Target    State     Host        
------------------------------------------------------------
ora.rac.db     application    ONLINE    OFFLINE               
ora....c1.inst application    ONLINE    ONLINE    rac1        
ora....c2.inst application    ONLINE    OFFLINE               
ora....C1.lsnr application    ONLINE    ONLINE    rac1        
ora.rac1.gsd   application    ONLINE    ONLINE    rac1        
ora.rac1.ons   application    ONLINE    ONLINE    rac1        
ora.rac1.vip   application    ONLINE    ONLINE    rac1        
ora....C2.lsnr application    ONLINE    OFFLINE               
ora.rac2.gsd   application    ONLINE    OFFLINE               
ora.rac2.ons   application    ONLINE    OFFLINE               
ora.rac2.vip   application    ONLINE    ONLINE    rac2        
oracle@rac1: /home/oracle> crs_stat -t
Name           Type           Target    State     Host        
------------------------------------------------------------
ora.rac.db     application    ONLINE    ONLINE    rac1        
ora....c1.inst application    ONLINE    ONLINE    rac1        
ora....c2.inst application    ONLINE    OFFLINE               
ora....C1.lsnr application    ONLINE    ONLINE    rac1        
ora.rac1.gsd   application    ONLINE    ONLINE    rac1        
ora.rac1.ons   application    ONLINE    ONLINE    rac1        
ora.rac1.vip   application    ONLINE    ONLINE    rac1        
ora....C2.lsnr application    ONLINE    OFFLINE               
ora.rac2.gsd   application    ONLINE    OFFLINE               
ora.rac2.ons   application    ONLINE    OFFLINE               
ora.rac2.vip   application    ONLINE    ONLINE    rac1

看到rac2.vip已经调到rac1上面了，再看看一直打开的sqlplus窗口


SQL> /

INSTANCE_NAME
--------------------------------
rac1

SQL> /

INSTANCE_NAME
--------------------------------
rac1

事实证明是不需要断开重连，起码sqlplus不需要，具体的代码不知道
整个failover过程需要大概30秒