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Oracle 11g dg broker automatic failover verification:

Db2 main library:

SQL > select DATABASE_ROLE,OPEN_MODE from v$database

DATABASE_ROLE OPEN_MODE

--

PRIMARY READ WRITE

Db1 is standby

SQL > select DATABASE_ROLE,OPEN_MODE from v$database

DATABASE_ROLE OPEN_MODE

--

PHYSICAL STANDBY READ ONLY WITH APPLY

Abnormal shutdown of db2 main library simulation

SQL > shu abort

ORACLE instance shut down.

Check the status of db1 again:

SQL > select DATABASE_ROLE,OPEN_MODE from v$database

DATABASE_ROLE OPEN_MODE

--

PRIMARY READ WRITE

Fourth: the process of automatic switching:

4.1Tests take about 10 seconds for observer to detect a failure in the main database!

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 the process of failover is the same as manual failover, whether it is automatic failver or manual execution of FAILOVER TO, the following two commands are executed using the command line failover:

Alter database recover managed standby database finish force;--- stops the rfs process

Alter database commit to switchover to primary;--- from open to mount

Alter database open;-read write to open

When failover occurs, you can see that this is indeed the process as follows

1)。 Start status: both rfs and mrp processes are normal

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 process disappears

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)。 The database becomes mounted.

SQL > select DATABASE_ROLE,OPEN_MODE from v$database

DATABASE_ROLE OPEN_MODE

--

PHYSICAL STANDBY MOUNTED

4) the database has become open write

SQL > select DATABASE_ROLE,OPEN_MODE from v$database

DATABASE_ROLE OPEN_MODE

--

PRIMARY READ WRITE

4.3execute failover manually

DGMGRL > help failover

Changes a standby database to be the primary database

Syntax:

FAILOVER TO [IMMEDIATE]

After the occurrence of failover:

Check the status of configuration: find the original master library needs to be reinstated, which needs to be repaired with the REINSTATE command before it can become the slave library of the new master library!

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

First, start the original main library to the mount state:

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

Check the original main library again:

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

In fact, reinstate performs the following process:

If you want to convert the original primary library to a new standby library

It is required that the original main library must have the function of flashbackup database turned on, after failover

1. Check the scn number when the slave failover becomes the master.

SQL > select STANDBY_BECAME_PRIMARY_SCN from v$database

STANDBY_BECAME_PRIMARY_SCN

-

15468

two。 Flash back the original main library to the scn number of 15468

SQL > FLASHBACK DATABASE TO SCN 15468

Database altered.

3. Perform the switch in the original main library:

SQL > alter database convert to physical standby

Database altered.

4. Close the original main library

SQL > shu immediate

5. Open the original main library to mount state

SQL > startup mount

6. Archive the newly generated logs to the new backup database on the new main database

SQL > alter system archive log current

7. Open the mrp process application log and repeat the changes

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

Database altered.

5. View status:

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

At this point, the original master library has become the new master standby.

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