Oracle DataGuard主备切换(switchover)

Oracle DataGuard主备切换可以使用传统的手动命令切换,也可以使用dgmgr切换,本文记录手动切换。

 

(一)将主库切换为物理备库

STEP1:查看主库状态

SQL>  SELECT OPEN_MODE, DATABASE_ROLE, SWITCHOVER_STATUS, FORCE_LOGGING, DATAGUARD_BROKER, GUARD_STATUS FROM V$DATABASE;

OPEN_MODE            DATABASE_ROLE    SWITCHOVER_STATUS    FOR DATAGUAR GUARD_S
-------------------- ---------------- -------------------- --- -------- -------
READ WRITE           PRIMARY          SESSIONS ACTIVE      YES DISABLED NONE

注意:需要检查SWITCHOVER_STATUS参数,如果值为"SESSION ACTIVE"或者"TO STANDBY", 则主数据库角色可以切换为备库角色。


STEP2:将其切换到备库,切换后,数据库会关闭

SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PHYSICAL STANDBY [WITH SESSION SHUTDOWN];

注意:如果上一步的SWITCH_STATUS参数值为"TO STANDBY",则 WITH SESSION SHUTDOWN 可以省略。

 

STEP3:启动到mount状态

SQL> SHUTDOWN ABORT
SQL> STARTUP MOUNT

注意:11.2.0.4版本及其以上版本不需要执行"SHUTDOWN ABORT",因为数据库已经在STEP2命令中关闭了。

 

(二) 将备库切换成主库并启动到open
STEP1:查看备库状态

SQL> SELECT OPEN_MODE, DATABASE_ROLE, SWITCHOVER_STATUS, FORCE_LOGGING, DATAGUARD_BROKER, GUARD_STATUS FROM V$DATABASE;

OPEN_MODE            DATABASE_ROLE    SWITCHOVER_STATUS    FOR DATAGUAR GUARD_S
-------------------- ---------------- -------------------- --- -------- -------
READ ONLY WITH APPLY PHYSICAL STANDBY TO PRIMARY           YES DISABLED NONE

注意:需要检查SWITCH_STATUS参数,如果值为"SESSION ACTIVE"或"TO PRIMARY",则备库可以切换为主库。


STEP2: 切换到主库

SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY [WITH SESSION SHUTDOWN];

注意:如果上一步的SWITCH_STATUS参数值为"TO PRIMARY",则 WITH SESSION SHUTDOWN 可以省略。


STEP3: 此时数据库为mount状态,需打开数据库

SQL> SELECT OPEN_MODE, DATABASE_ROLE, SWITCHOVER_STATUS, FORCE_LOGGING, DATAGUARD_BROKER, GUARD_STATUS FROM V$DATABASE;

OPEN_MODE            DATABASE_ROLE    SWITCHOVER_STATUS    FOR DATAGUAR GUARD_S
-------------------- ---------------- -------------------- --- -------- -------
MOUNTED              PRIMARY          NOT ALLOWED          YES DISABLED NONE

SQL> ALTER DATABASE OPEN ;

Database altered.

SQL>  SELECT OPEN_MODE, DATABASE_ROLE, SWITCHOVER_STATUS, FORCE_LOGGING, DATAGUARD_BROKER, GUARD_STATUS FROM V$DATABASE;

OPEN_MODE            DATABASE_ROLE    SWITCHOVER_STATUS    FOR DATAGUAR GUARD_S
-------------------- ---------------- -------------------- --- -------- -------
READ WRITE           PRIMARY          TO STANDBY           YES DISABLED NONE


(三)新的备库开启日志应用

SQL> ALTER DATABASE OPEN;
SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE DISCONNECT;

 

【完】

 

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posted @ 2020-07-18 13:40  gegeman  阅读(2803)  评论(0编辑  收藏  举报