Oct 12 2017

Oracle 12c R2 (12.2.0.1) Real Time Apply Data Guard Installation on Oracle Linux 7.3

Category: Administration,Backup And RecoveryFatih Acar @ 11:11

Oracle Data Guard ensures high availability, data protection, and disaster recovery for enterprise data. Oracle Data Guard provides a comprehensive set of services that create, maintain, manage, and monitor one or more standby databases to enable production Oracle databases to survive disasters and data corruptions. Oracle Data Guard maintains these standby databases as copies of the production database.Then, if the production database becomes unavailable because of a planned or an unplanned outage, Oracle Data Guard can switch any standby database to the production role, minimizing the downtime associated with the outage. Oracle Data Guard can be used with traditional backup, restoration, and cluster techniques to provide a high level of data protection and data availability.

With Oracle Data Guard, administrators can optionally improve production database performance by offloading resource-intensive backup and reporting operations to standby systems.

Types of standby databases are Physical standby database, Logical standby database and Snapshot standby database.

I will demonstrate Physical standby database as working real time apply at this document. Most used type is Physical standby database type. You can investigate other types of standby database from Oracle docs.

I used Oracle RAC database as primary side and I used single instance database with asm file system as secondary side (Data Guard).

Firstly, you have to adjust system parameters of operating system on secondary side and create asm disks. After, you can start to install of grid infrastructure. You can create disk groups for DATA and FRA disk groups after install grid. After grid installation, you can install Oracle Data Guard database on grid infrastructure and ASM disks as software only. Finally you can restore and recover standby database from primary side and you can start synchronization apply after add standby redo log. I divide the stages of installation five steps.

You can find primary side (Oracle 12c RAC) installation steps here. I will use this infrastructure as primary side.

First Step : Configure Operation System on Secondery Side

1. Upgrade Packages

yum upgrade

yum install oracleasm-support

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Tags: Oracle 12c, Oracle Administration, Oracle Backup and Restore, Oracle Data Guard


Mar 28 2017

Oracle 11g R2 Open Data Guard Read Write Mode With Flashback Technology And Revert Restore Point

Category: Administration,Backup And RecoveryFatih Acar @ 13:34

You can use flashback technology on standby side. If you want to make application test on database, you can use data guard as read write mode temporarily with flashback technology. You can create a restore point on standby side then you can do any transaction on standby side to test or any other purpose. After you complete your operations on the standby side, you can revert to restore point and again connect to primary side and apply logs from primary side.

This feature can be use for application test operations.

Perform Flashback Steps

Standby Side


SQL> alter database recover managed standby database cancel;

Database altered.

SQL> alter database flashback on;

Database altered.

Note : Check recovery destination and size. You have to have recovery dest and size.

SQL> show parameter recovery

NAME				     TYPE	 VALUE
------------------------------------ ----------- ------------------------------
db_recovery_file_dest		     string	 /oracle/fra
db_recovery_file_dest_size	     big integer 10G
recovery_parallelism		     integer	 0

SQL> create restore point before_test guarantee flashback database;

Restore point created.

Primary Side


SQL> alter system archive log current;

System altered.

Note : Archive dest for standby log sync parameter set defer.

SQL> alter system set log_archive_dest_state_2=defer;

System altered.

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Tags: Database Administration, Oracle Administration, Oracle Backup and Restore, Oracle Data Guard


Mar 28 2017

Oracle 11g R2 Data Guard Manual Switchover Steps

Category: Administration,Backup And RecoveryFatih Acar @ 09:47

You can use the same steps to switchover for single data guard or multiple data guard configuration.

Switchover operation will convert primary side to data guard and data guard to primary side.

You have to control listeners whether it is running before switchover steps.

Switchover Steps

Primary Side


SQL> alter system archive log current;

SQL> alter database commit to switchover to standby with session shutdown;

SQL> shutdown immediate;

SQL> startup mount;

Data Guard Side
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Tags: Database Administration, Oracle Administration, Oracle Data Guard, Oracle Data Guard Switchover


Mar 18 2013

Limits of Oracle Data Guard

Category: Administration,Backup And RecoveryFatih Acar @ 17:49

Important situations of Oracle Data Guard

  • Nologging or unrecoverable operations are not applied to standby – so be cautious in using those options. Alarming data block corruption error messages are reported if a user attempts to access any nologging or unrecoverable data blocks.
  • ‘Drop tablespace’, ‘drop datafile’, ‘rename datafile’, and add/drop online redo log files operations need done on both nodes manually.
  • Initialization parameter changes need done on both nodes manually.
  • For databases upgrades, the software in the new ORACLE_HOME must be separately installed on both nodes. The database part of the upgrade is carried out only on the primary database.
    Often Data Guard replication is suspended for a significant period of time during and following the primary database upgrade. That is done with DGMGRL> edit database ‘mydb_sby’ set state=’APPLY-OFF’ ;. The standby server is only upgraded, and replication resumed, once the primary upgrade has been determined to be a success.
  • For patches, the software/binaries in the ORACLE_HOME must be separately patched on both nodes.  The database part of the patch (if any) is carried out only on the primary database.

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Tags: Database Administration, Oracle Administration, Oracle Data Guard


Mar 10 2013

How to Add Standby Logfile in Oracle

Category: Administration,Backup And RecoveryFatih Acar @ 17:59

If you want to use real-time apply Oracle Data Guard, you have to add standby logfile to standby database.

Show Logfiles Before Add

SQL> select * from gv$logfile;

INST_ID GROUP# STATUS TYPE MEMBER IS_RECOVERY_DEST_FILE
1 3 ONLINE +DATA/testdb/onlinelog/group_3.14134123 NO
1 1 ONLINE +DATA/testdb/onlinelog/group_1.35116731 NO
1 2 ONLINE +DATA/testdb/onlinelog/group_2.32513245 NO
1 4 ONLINE +DATA/testdb/onlinelog/group_4.12255335 NO
1 2 ONLINE +FRA/testdb/onlinelog/group_2.13423425 YES
1 1 ONLINE +FRA/testdb/onlinelog/group_1.53242411 YES
1 3 ONLINE +FRA/testdb/onlinelog/group_3.34634123 YES
1 4 ONLINE +FRA/testdb/onlinelog/group_4.32525244 YES

Add Standby Logfile ASM

SQL> alter database add standby logfile ‘+DATA’ size 52428800;

Add Standby Logfile FileSystem

SQL> alter database add standby logfile ‘/oracle/db/datafile/standby_redo01.rdo’ size 52428800;

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Tags: Database Administration, Oracle Administration, Oracle Data Guard