Oracle 11g Books

Oracle tuning

Oracle training

Oracle support

Remote Oracle

STATSPACK Viewer

Privacy Policy

Flashback Re-instantiation tips Oracle Tips by Burleson

Oracle 10g Flashback Re-instantiation

In an Oracle9i Data Guard environment, a failover operation leads to a resetlogs.  This operation invalidates the old primary database. Therefore, you need to perform a hot backup on the new primary database immediately, and then re-create a new standby database.  This operation can take a long time, and your new primary database is vulnerable during this period.

The new Flashback Re-instantiation feature reduces the need to reinstantiate the old primary database following a failover. This feature allows you to quickly restore full resiliency after a failure. This is accomplished by using the SQL statement FLASHBACK DATABASE to roll back the old primary database in time to synchronize with the old standby database.

 Figure 12.4 Flashback Re-instantiation of Standby Database

Here are the steps to perform Flashback Re-instantiation:

1. On your new primary database (Instance B):

SQL> select standby_became_primary_scn from v$database;

STANDBY_BECAME_P
----------------
2960985

2. Mount the old primary database (Instance A).

SQL> STARTUP MOUNT

3. Flashback the old primary database (Instance A) to the SCN.

SQL> flashback database to scn 2960985;

4. Disable Flashback on the old primary database (Instance A).

SQL> ALTER DATABASE FLASHBACK OFF;

5. On the old primary database (Instance A), create a standby control file.

SQL> alter database create standby controlfile
     as'/dba/standby/stbycf.f' reuse;

6. Shutdown the old primary database (Instance A), and replace the control files with the new standby control files.

SQL> shutdown immediate;
$ cp /dba/standby/stbyct.f  /u02/oradata/sid/control01.ctl
$ cp /dba/standby/stbyct.f  /u02/oradata/sid/control02.ctl

7. Bring up the old primary database as a new physical standby database (Instance A).

SQL> startup mount;

8. Turn flashback back on the new primary database (Instance A).

9. Oracle10g Flashback Re-instantiation

   SQL> alter database flashback on;

10. Enable transport from the new primary database (Instance B)

11. SQL> ALTER SYSTEM SET LOG_ARCHIVE_DEST_STATE_1=ENABLE;

12. On the new standby database (Instance A), start real time apply.

13. SQL> RECOVER MANAGED STANDBY DATABASE using current logfile DISCONNECT;

14. The Managed Recovery process (MRP) will hit the End-Of-Redo and then need to be restarted.

15. SQL> RECOVER MANAGED STANDBY DATABASE using current logfile DISCONNECT;