Oracle data guard 主库备库切换演练

本实验做的是将primary主库和standby 备库进行切换演练

步骤如下： 
1 在主库端检查数据库可切换状态

SQL> select switchover_status from v$database;
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SWITCHOVER_STATUS–>TO STANDBY,表示可以正常切换. 
SWITCHOVER_STATUS–>SESSIONS ACTIVE,表示当前有会话处于ACTIVE状态

2 开始主库正常切换 
如果SWITCHOVER_STATUS 的值为TO STANDBY：

SQL> alter database commit to switchover to physical standby;
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如果SWITCHOVER_STATUS 的值为SESSIONS ACTIVE：

SQL> alter database commit to switchover to physical standby with session shutdown;
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3 重启主库

SQL> shutdown abort;SQL> startup mount;
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4 到备库验证可切换状态

SQL> select switchover_status from v$database;SWITCHOVER_STATUS-----------------TO_PRIMARY
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5 将目标备库转换为主库 
如果SWITCHOVER_STATUS 的值为TO STANDBY 则:

SQL> alter database commit to switchover to primary;
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如果SWITCHOVER_STATUS 的值为SESSIONS ACTIVE 则:

SQL> alter database commit to switchover to primary with session shutdown;
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6 打开目标备库

SQL> alter database open;
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7 开始在目标备库应用日志

SQL> alter database recover managed standby database disconnect;
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8 检查主备库角色状态：

SQL> select switchover_status,database_role from v$database;