Snapshot Standby ( Read Write ) in Oracle Dataguard

Hi,

In this article I will explain you the steps to convert Dataguard to Read Write mode.

 

 

I have explained you to open in synchronized dataguard in Read only mode as Active standby in the Following article. In this article, I will tell you how to convert Dataguard to write Read Write mode and then to convert it into dataguard mode again.

 

 

Flashback must be turned on in order to be able to active standby mode. To enable Flashback, we need to use the FRA parameter like following.

 

SQL> show parameter db_recovery_file

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_recovery_file_dest string /u01/recovery_area
db_recovery_file_dest_size big integer 2022043K

 

Flashback is enabled as follows. This can be done in case the dataguard is off and in mount mode.

 

 SQL> alter database flashback on;

Database altered.

 

Create a guaranteed restore point. When we convert to dataguard, we will use this restore point.

SQL> create restore point before_open guarantee flashback database;

Restore point created.

 

 

Stop Redo Apply process

SQL> alter database recover managed standby database cancel;

 

Manually create an archive log in the primary database like following.

 SQL> alter system archive log current;
System altered.

 

 

We need to delay the redo transport from the Primary Database to the Standby database. So disable related log_archive_dest_state_2 parameter like following.

SQL> alter system set log_archive_dest_state_2=DEFER; 
SQL> alter system switch logfile;


Now we can activate the Standby database and convert it into Read Write mode.

SQL> alter database activate standby database;
Database altered.

 

 

Open standby database in read and write mode

SQL> startup mount force;
ORACLE instance started.

Total System Global Area 534462464 bytes
Fixed Size 2230072 bytes
Variable Size 163580104 bytes
Database Buffers 360710144 bytes
Redo Buffers 7942144 bytes
Database mounted.


alter database set standby database to maximize performance;

alter database open;

Database altered.

 

 

We opened the standby database in Read write mode namely Snapshot database mode.

This operation is done such as test or Disaster purpose.

 

SQL> create user mehmet identified by salih;

User created.

SQL> grant dba to mehmet;

Grant succeeded.

 

If Disaster tests or any other tests are completed, we can convert it into dataguard again like following steps.

 

Open it in Mount mode

SQL> startup mount force;
ORACLE instance started.

Total System Global Area 534462464 bytes
Fixed Size 2230072 bytes
Variable Size 163580104 bytes
Database Buffers 360710144 bytes
Redo Buffers 7942144 bytes
Database mounted.

 

Convert Snapshot database to Dataguard with restore point

 

select * from v$restore_point;

set pages 100
set line 200
column message format a50
select sid,message from v$session_longops where 
sofar <> totalwork;

set linesize 400
col DB_DATA for 999999999999
col FLASHBACK_SIZE for 999999999999
SELECT TO_CHAR(A.BEGIN_TIME,'DDMMYY HH24:MI') "FLASH BEGIN",TO_CHAR(A.END_TIME,'DDMMYY HH24:MI') "FLASH END",A.DB_DATA, B.FLASHBACK_SIZE, (A.DB_DATA/B.FLASHBACK_SIZE)*100 "% COMPLETE" FROM V$FLASHBACK_DATABASE_STAT A, V$FLASHBACK_DATABASE_LOG B;

  SQL> flashback database to restore point BEFORE_OPEN;

DROP RESTORE POINT before_readwrite0612_2016;

Flashback complete.

 

Convert Snapshot database to the standby database.

3- SQL> alter database convert to physical standby;

Database altered.

 

The Standby database is reopened in Mount mode.

SQL> startup mount force;
ORACLE instance started.

Total System Global Area 534462464 bytes
Fixed Size 2230072 bytes
Variable Size 163580104 bytes
Database Buffers 360710144 bytes
Redo Buffers 7942144 bytes
Database mounted.

 

Redo Apply is started again like following.

alter database recover managed standby database using current logfile disconnect;

 

 

Mehmet Salih Deveci

I am Certified Expert about Oracle & SQL Server database, Goldengate, Exadata Machine, Oracle Database Appliance administrator with 10+years experience.I have OCA, OCP, OCE RAC Expert Certificates I have worked 100+ Banking, Insurance, Finance, Telco and etc. clients as a Consultant, Insource or Outsource.I have done 200+ Operations in this clients such as Exadata Installation & PoC & Migration & Upgrade, Oracle & SQL Server Database Upgrade, Oracle RAC Installation, SQL Server AlwaysOn Installation, Database Migration, Disaster Recovery, Backup Restore, Performance Tuning, Periodic Healthchecks.I have done 2000+ Table replication with Goldengate or SQL Server Replication tool for DWH Databases in many clients.If you need Oracle DBA, SQL Server DBA, APPS DBA,  Exadata, Goldengate, EBS Consultancy and Training you can send my email adress mehmetsalih.deveci@outlook.com.Oracle DBA, SQL Server DBA, APPS DBA,  Exadata, Goldengate, EBS ve linux Danışmanlık ve Eğitim için  mehmetsalih.deveci@outlook.com a mail atabilirsiniz.

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