Oracle 11g dg broker自動failover驗證：

db2主庫：

SQL> select DATABASE_ROLE,OPEN_MODE from v$database;

DATABASE_ROLE OPEN_MODE

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

PRIMARY READ WRITE

db1為standby

SQL> select DATABASE_ROLE,OPEN_MODE from v$database;

DATABASE_ROLE OPEN_MODE

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

PHYSICAL STANDBY READ ONLY WITH APPLY

db2主庫模擬異常關閉

SQL> shu abort

ORACLE instance shut down.

再次檢視db1的狀態：

SQL> select DATABASE_ROLE,OPEN_MODE from v$database;

DATABASE_ROLE OPEN_MODE

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

PRIMARY READ WRITE

四：自動切換的過程：

4.1:測試大概需要10秒observer去探測到主庫發生故障！

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的過程和手工failover一樣，不管是自動failver，還是手動執行FAILOVER TO ，都是執行了用命令列failover的命令如下兩條命令：

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

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

alter database open; ----read write 方式開啟

發生failover的時候，透過如下可以看到確實是這麼個過程

1）.開始狀態: rfs和mrp程式都正常

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程式消失

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

PROCESS STATUS SEQUENCE#

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

ARCH CONNECTED 0

ARCH CLOSING 14

MRP0 APPLYING_LOG 15

3）.資料庫變成了mounted

SQL> select DATABASE_ROLE,OPEN_MODE from v$database;

DATABASE_ROLE OPEN_MODE

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

PHYSICAL STANDBY MOUNTED

4）資料庫變成open write了

SQL> select DATABASE_ROLE,OPEN_MODE from v$database;

DATABASE_ROLE OPEN_MODE

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

PRIMARY READ WRITE

4.3：手動執行failover；

DGMGRL> help failover

Changes a standby database to be the primary database

Syntax:

FAILOVER TO <standby database name> [IMMEDIATE];

當發生failover的之後：

檢視 configuration的狀態：發現原來的主庫 needs to be reinstated，需要使用REINSTATE命令修復下，才能變成新的主庫的從庫！

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

首先啟動原來的主庫到mount狀態：

SQL> startup mount

DGMGRL> help reinstate

Changes a database marked for reinstatement into a viable standby

Syntax:

REINSTATE DATABASE <database name>;

DGMGRL> REINSTATE DATABASE db1

Reinstating database "db1", please wait...

Reinstatement of database "db1" succeeded

再次檢視原來的主庫：

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

實際上reinstate就是執行了下面的過程：

如果要轉換原來的主庫為新的備庫

要求原先的主庫必須開啟了flashbackup database的功能，在failover後，

1.檢視從庫failover成為主的時候的scn號。

SQL> select STANDBY_BECAME_PRIMARY_SCN from v$database;

STANDBY_BECAME_PRIMARY_SCN

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

15468

2.閃回原來的主庫到15468 的scn號；

SQL>FLASHBACK DATABASE TO SCN 15468 ;

Database altered.

3.在原來主庫執行切換：

SQL> alter database convert to physical standby ;

Database altered.

4.關閉原來的主庫

SQL>shu immediate

5.開啟原來的主庫到mount狀態，

SQL>startup mount;

6.在新的主庫上把新產生的日誌歸檔到新的備庫

SQL>alter system archive log current;

7.開啟mrp程式應用日誌，重演變化

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

Database altered.

5.檢視狀態：

SQL> select process,status from v$managed_standby;

PROCESS STATUS

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

ARCH CLOSING

ARCH CONNECTED

ARCH CLOSING

MRP0 APPLYING_LOG

RFS IDLE

至此將原來的主庫成為了新的主的standby了。。。。。

​Oracle 11g dg broker自動failover

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Oracle 11g dg broker自動failover