Oracle11gdgbroker如何自动failover

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Oracle 11g dg broker自动failover验证：

db2主库：

SQL> select DATABASE_ROLE,OPEN_MODE from v$database;

DATABASE_ROLE OPEN_MODE

---------------- --------------------

PRIMARY READ WRITE

db1为standby

SQL> select DATABASE_ROLE,OPEN_MODE from v$database;

DATABASE_ROLE OPEN_MODE

---------------- --------------------

PHYSICAL STANDBY READ ONLY WITH APPLY

db2主库模拟异常关闭

SQL> shu abort

ORACLE instance shut down.

再次查看db1的状态：

SQL> select DATABASE_ROLE,OPEN_MODE from v$database;

DATABASE_ROLE OPEN_MODE

---------------- --------------------

PRIMARY READ WRITE

四：自动切换的过程：

4.1:测试大概需要10秒observer去探测到主库发生故障！

DGMGRL> start observer;

Observer started

20:15:59.44 Thursday, July 04, 2019

Initiating Fast-Start Failover to database "db2"...

Performing failover NOW, please wait...

Failover succeeded, new primary is "db2"

20:16:01.77 Thursday, July 04, 2019

4.2 failover的过程和手工failover一样，不管是自动failver，还是手动执行FAILOVER TO ，都是执行了用命令行failover的命令如下两条命令：

alter database recover managed standby database finish force;---停止rfs进程

alter database commit to switchover to primary;---由open到mount

alter database open; ----read write 方式打开

发生failover的时候，通过如下可以看到确实是这么个过程

1）.开始状态: rfs和mrp进程都正常

SQL> select process,status ,sequence# from v$managed_standby;

PROCESS STATUS SEQUENCE#

--------- ------------ ----------

ARCH CONNECTED 0

ARCH CLOSING 14

RFS IDLE 0

RFS IDLE 15

RFS IDLE 0

MRP0 APPLYING_LOG 15

8 rows selected.

2）.rsf进程消失

SQL> select process,status ,sequence# from v$managed_standby;

PROCESS STATUS SEQUENCE#

--------- ------------ ----------

ARCH CONNECTED 0

ARCH CLOSING 14

MRP0 APPLYING_LOG 15

3）.数据库变成了mounted

SQL> select DATABASE_ROLE,OPEN_MODE from v$database;

DATABASE_ROLE OPEN_MODE

---------------- --------------------

PHYSICAL STANDBY MOUNTED

4）数据库变成open write了

SQL> select DATABASE_ROLE,OPEN_MODE from v$database;

DATABASE_ROLE OPEN_MODE

---------------- --------------------

PRIMARY READ WRITE

4.3：手动执行failover；

DGMGRL> help failover

Changes a standby database to be the primary database

Syntax:

FAILOVER TO [IMMEDIATE];

当发生failover的之后：

查看 configuration的状态：发现原来的主库 needs to be reinstated，需要使用REINSTATE命令修复下，才能变成新的主库的从库！

DGMGRL> show configuration

Configuration - dbha_c

Protection Mode: MaxPerformance

Databases:

db2 - Primary database

Warning: ORA-16829: fast-start failover configuration is lagging

db1 - (*) Physical standby database (disabled)

ORA-16661: the standby database needs to be reinstated

Fast-Start Failover: ENABLED

Configuration Status:

WARNING

首先启动原来的主库到mount状态：

SQL> startup mount

DGMGRL> help reinstate

Changes a database marked for reinstatement into a viable standby

Syntax:

REINSTATE DATABASE ;

DGMGRL> REINSTATE DATABASE db1

Reinstating database "db1", please wait...

Reinstatement of database "db1" succeeded

再次查看原来的主库：

SQL> select process,status ,sequence# from v$managed_standby;

PROCESS STATUS SEQUENCE#

--------- ------------ ----------

ARCH CONNECTED 0

ARCH CLOSING 5

RFS IDLE 0

RFS IDLE 6

MRP0 APPLYING_LOG 6

实际上reinstate就是执行了下面的过程：

如果要转换原来的主库为新的备库

要求原先的主库必须开启了flashbackup database的功能，在failover后，

1.查看从库failover成为主的时候的scn号。

SQL> select STANDBY_BECAME_PRIMARY_SCN from v$database;

STANDBY_BECAME_PRIMARY_SCN

--------------------------

15468

2.闪回原来的主库到15468 的scn号；

SQL>FLASHBACK DATABASE TO SCN 15468 ;

Database altered.

3.在原来主库执行切换：

SQL> alter database convert to physical standby ;

Database altered.

4.关闭原来的主库

SQL>shu immediate

5.打开原来的主库到mount状态，

SQL>startup mount;

6.在新的主库上把新产生的日志归档到新的备库

SQL>alter system archive log current;

7.打开mrp进程应用日志，重演变化

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

Database altered.

5.查看状态：

SQL> select process,status from v$managed_standby;

PROCESS STATUS

--------- ------------

ARCH CLOSING

ARCH CONNECTED

ARCH CLOSING

MRP0 APPLYING_LOG

RFS IDLE

至此将原来的主库成为了新的主的standby了。。。。。

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