DG模拟主库故障利用闪回恢复主备库

如果数据库开启了闪回功能，可以通过闪回数据库功能快速恢复DG环境。不过利用闪回数据库技术进行DG恢复会有部分数据丢失风风险！(亲测)

模拟故障之前先对主备库开启闪回功能，环境为oracle19c 单实例DG数据库启动到mount状态执行：alter database flashback on;alter database open;---(主备库)。

然后 正式模拟：

1、主库

shutdown abort

2、备库检查状态

select name,open_mode,database_role,switchover_status from v$database;

3、备库关闭日志应用

ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;

4、备库切换成新主库

ALTER DATABASE ACTIVATE PHYSICAL STANDBY DATABASE;

5、查询数据库新主库状态

select name,open_mode,database_role,switchover_status from v$database;

6、打开新主库并查询scn号

alter database open;

SELECT TO_CHAR(STANDBY_BECAME_PRIMARY_SCN) std_scn FROM V$DATABASE;

7、原主库(新备库)启动到mount恢复到新主库查询到的scn节点

startup mount

flashback database to scn 3112752;

8、原主库切换成新备库并启动到mount

alter database convert to physical standby;

shutdown immediate

startup mount

9、新备库开启日志应用

alter database recover managed standby database using current logfile disconnect from session;

10、查询新主库发现有GAP

select thread#, low_sequence#, high_sequence# from v$archive_gap;

select name,open_mode,database_role,switchover_status from v$database;

11、新主库启动到mount把日志刷入新备库

startup mount

alter system flush redo to dg1;

12、打开新主库

alter database open;

select name,open_mode,database_role,switchover_status from v$database;

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