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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(guān)閉
SQL> shu abort
ORACLE instance shut down.
再次查看db1的狀態(tài)：
SQL> select DATABASE_ROLE,OPEN_MODE from v$database;
DATABASE_ROLE OPEN_MODE
---------------- --------------------
PRIMARY READ WRITE
四：自動切換的過程：
4.1:測試大概需要10秒observer去探測到主庫發(fā)生故障！
DGMGRL> start observer;
Observer started
20:15:59.44 Thursday, July 04, 2019
Initiating Fast-Start Failover to database "db2"...
Performing failover NOW, please wait...
Failover succeeded, new primary is "db2"
20:16:01.77 Thursday, July 04, 2019
4.2 failover的過程和手工failover一樣，不管是自動failver，還是手動執(zhí)行FAILOVER TO ，都是執(zhí)行了用命令行failover的命令如下兩條命令：
alter database recover managed standby database finish force;---停止rfs進程
alter database commit to switchover to primary;---由open到mount
alter database open; ----read write 方式打開
發(fā)生failover的時候，通過如下可以看到確實是這么個過程
1）.開始狀態(tài): rfs和mrp進程都正常
SQL> select process,status ,sequence# from v$managed_standby;
PROCESS STATUS SEQUENCE#
--------- ------------ ----------
ARCH CONNECTED 0
ARCH CONNECTED 0
ARCH CONNECTED 0
ARCH CLOSING 14
RFS IDLE 0
RFS IDLE 15
RFS IDLE 0
MRP0 APPLYING_LOG 15
8 rows selected.
2）.rsf進程消失
SQL> select process,status ,sequence# from v$managed_standby;
PROCESS STATUS SEQUENCE#
--------- ------------ ----------
ARCH CONNECTED 0
ARCH CONNECTED 0
ARCH CONNECTED 0
ARCH CLOSING 14
MRP0 APPLYING_LOG 15
3）.數(shù)據(jù)庫變成了mounted
SQL> select DATABASE_ROLE,OPEN_MODE from v$database;
DATABASE_ROLE OPEN_MODE
---------------- --------------------
PHYSICAL STANDBY MOUNTED
4）數(shù)據(jù)庫變成open write了
SQL> select DATABASE_ROLE,OPEN_MODE from v$database;
DATABASE_ROLE OPEN_MODE
---------------- --------------------
PRIMARY READ WRITE
4.3：手動執(zhí)行failover；
DGMGRL> help failover
Changes a standby database to be the primary database
Syntax:
FAILOVER TO
當(dāng)發(fā)生failover的之后：
查看 configuration的狀態(tài)：發(fā)現(xiàn)原來的主庫 needs to be reinstated，需要使用REINSTATE命令修復(fù)下，才能變成新的主庫的從庫！
DGMGRL> show configuration
Configuration - dbha_c
Protection Mode: MaxPerformance
Databases:
db2 - Primary database
Warning: ORA-16829: fast-start failover configuration is lagging
db1 - (*) Physical standby database (disabled)
ORA-16661: the standby database needs to be reinstated
Fast-Start Failover: ENABLED
Configuration Status:
WARNING
首先啟動原來的主庫到mount狀態(tài)：
SQL> startup mount
DGMGRL> help reinstate
Changes a database marked for reinstatement into a viable standby
Syntax:
REINSTATE DATABASE
DGMGRL> REINSTATE DATABASE db1
Reinstating database "db1", please wait...
Reinstatement of database "db1" succeeded
再次查看原來的主庫：
SQL> select process,status ,sequence# from v$managed_standby;
PROCESS STATUS SEQUENCE#
--------- ------------ ----------
ARCH CONNECTED 0
ARCH CONNECTED 0
ARCH CONNECTED 0
ARCH CLOSING 5
RFS IDLE 0
RFS IDLE 0
RFS IDLE 0
RFS IDLE 6
MRP0 APPLYING_LOG 6
實際上reinstate就是執(zhí)行了下面的過程：
如果要轉(zhuǎn)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后，
1.查看從庫failover成為主的時候的scn號。
SQL> select STANDBY_BECAME_PRIMARY_SCN from v$database;
STANDBY_BECAME_PRIMARY_SCN
--------------------------
15468
2.閃回原來的主庫到15468 的scn號；
SQL>FLASHBACK DATABASE TO SCN 15468 ;
Database altered.
3.在原來主庫執(zhí)行切換：
SQL> alter database convert to physical standby ;
Database altered.
4.關(guān)閉原來的主庫
SQL>shu immediate
5.打開原來的主庫到mount狀態(tài)，
SQL>startup mount;
6.在新的主庫上把新產(chǎn)生的日志歸檔到新的備庫
SQL>alter system archive log current;
7.打開mrp進程應(yīng)用日志，重演變化
SQL> alter database recover managed standby database using current logfile disconnect from session;
Database altered.
5.查看狀態(tài)：
SQL> select process,status from v$managed_standby;
PROCESS STATUS
--------- ------------
ARCH CLOSING
ARCH CONNECTED
ARCH CONNECTED
ARCH CLOSING
MRP0 APPLYING_LOG
RFS IDLE
RFS IDLE
RFS IDLE
至此將原來的主庫成為了新的主的standby了。。。。。
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