DataGuard角色切换

最新推荐文章于 2024-12-02 16:11:37 发布

最新推荐文章于 2024-12-02 16:11:37 发布 · 76 阅读

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本文详细介绍了Oracle数据库从主库切换到备用库的过程，包括验证主库能够切换到备用角色、初始化主库上的切换操作、关闭并挂载前主库等步骤。通过具体的SQL命令示例，展示了如何处理切换过程中可能出现的介质恢复需求。

Step 1 Verify that the primary database can be switched to the standby role.
验证主库能够切换到备用角色。
SELECT SWITCHOVER_STATUS FROM V$DATABASE;
idle>:wq

SWITCHOVER_STATUS
--------------------
TO STANDBY

Step 2 Initiate the switchover on the primary database.
在主库上面开始切换
alter database commit to switchover to physical standby with session shutdown ;

Step 3 Shut down and then mount the former primary database.
关闭并且mount上从前的主库。

shutdown abort;
startup mount ;

Step 4 Verify that the switchover target is ready to be switched to the primary role.
验证转换目标已经准备好转换为主库角色
SWITCHOVER_STATUS
--------------------
SWITCHOVER LATENT

这里查询出来的值不为TO_PRIMARY即有点问题。
执行下一步的时候可能会出现问题。

Step 5 Switch the target physical standby database role to the primary role.
转换目标逻辑备用库角色为主库角色。

sys@DEX> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY WITH SESSION SHUTDOWN;
ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY WITH SESSION SHUTDOWN
*
ERROR at line 1:
ORA-16139: media recovery required

这里提示需要介质恢复。

sys@DEX> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION;

Database altered.

sys@DEX> SELECT SWITCHOVER_STATUS FROM V$DATABASE;

SWITCHOVER_STATUS
--------------------
TO PRIMARY

sys@DEX> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY WITH SESSION SHUTDOWN;

Database altered.

Step 6 Open the new primary database.
打开新的主库
sys@DEX> ALTER DATABASE OPEN;

Database altered.

Step 7 Verify the switch role .
验证角色转换

主库执行
sys@DEX> alter system switch logfile ;

System altered.

sys@DEX> select sequence# from v$log ;

SEQUENCE#
----------
40
41
42

sys@DEX>

standby库执行

sys@DEX> select sequence# from v$log ;

SEQUENCE#
----------
40
42
41

sys@DEX>