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You must then re-create it from a copy of the new primary database and reenable it as described in How to Re-create and Reenable a Disabled Database. In addition, the database to be reinstated and the new After fast-start failover is enabled and up to four observers are started, one observer is nominated as the master observer that continuously monitors the environment to ensure the primary database is available. Only the observer can initiate FSFO failover. If the primary is unable to contact the standby after a user specified period of time (NET_TIMEOUT option of log_archive_dest_ n), it drops out of synchronous transfer mode and begins operating as though it were in Maximum Performance mode. The first step in reinstatement is to flash the database back to the SCN where the standby became the primary (v$database.standby_became_primary_scn on the new primary). The following is a sample observer configuration file: Since the broker configuration SALES consists of three databases, Boston, Chicago, and Dallas, with a CONNECT_ID of SALES_P, the SALES_P connect identifier must be defined such that it can reach any instance of any database within the configuration. You will have to reinstate or re-create (see Reenabling Disabled Databases After a Role Change) the standby databases after failover has completed. For example: Using DGMGRL, you can do this by examining the output of the SHOW CONFIGURATION LAG. In this case fast-start failover cannot occur because the databases are not ready to failover. Oracle Data Guard is a solution provider to businesses by offering data protection and its disaster recovery along with its high availability. Note: if the observer loses contact with the primary, but the standby does not, the observer can determine that the primary is still up via the standby. To stop the observer when fast-start failover is enabled, the primary database and target standby database must be connected and communicating with each other. there is a lost network connection, be aware that the observer may attempt a Flashing back a database occurs in two stages: For FSFO environments, set db_flashback_retention_target = 60 or higher to provide sufficient Flashback Database history for automatic standby reinstatement. It automatically sets Data Guard related database initialization parameters on instance start and role transitions, starts apply services for standbys, and automates many of the administrative tasks associated with maintaining a Data Guard configuration. Instead, the old primary database must be re-created as a standby from a backup of the new primary using the procedure described in How to Re-create and Reenable a Disabled Database. You can also query the V$FS_FAILOVER_STATS view to display statistics about fast-start failover occurring on the system. switch does not happen until the next time the primary contacts the target standby, Fast-start failover enables the Data Guard broker to rapidly and automatically failover to a previously chosen standby database without requiring manual intervention. The database on which the procedure is called notifies the observer. Data Guard broker publishes this service on each instance as it comes up and broker management of the instance is initialized: To patch an environment where the Observer is running and fast-start failover is enabled, follow these steps prior to applying the patch. If fast-start failover is already enabled, the Applications can initiate FSFO failover directly using the DBMS_DG.INITIATE_FS_FAILOVER procedure with an optional message text that will be displayed in the observer log and the primary's alert log. It behaves similarly to START OBSERVING and STOP OBSERVING to operate on all the configurations defined in the observer configuration file. SHOW OBSERVERS [FOR fg_group_name ] shows information about observers for all configurations in the specified group. multi-tenant environments Know the database downgrade steps in case the upgraded database isn't compatible with the environment Discover the features and benefits to the organization when it moves from the old database . Broker Configuration Has Only One Registered Observer. If all the databases do not have the same values, SRVCTL attempts to override the values, which will fail on the physical standby database because it is open read-only. If there are many actions that need to take place, put them in a separate script and use the trigger to run the script in an orphan process or thread independent of the database. For reliable startup, the initial connection should always be made to the primary. You can also reinstate bystander standby databases that were disabled during a failover operation. In a manual failover, you convert a standby database to a primary database because the original primary database failed and there is no possibility of recovering the primary database in a timely manner. directory. Click Disable in the Fast-Start Failover wizard. Only the master observer can coordinate fast-start failover with Data Guard broker. If the database is not managed by Oracle Clusterware, Using Shared Server (MTS) or connection pooling can result in unpredictable behavior. In such cases, the failed primary database is reinstated as a physical standby database. lower detection times for primary database failures. They rely on Oracle Data Guard for high availability databases, with a standby database running in a different availability zone. Observers should be installed and run on a computer system that is separate from the primary and standby systems. Required fields are marked *. Issue the following SRVCTL commands so that both databases in the Data Guard configuration know about the two potential services for each database: To start things up initially, you must manually start the services on the right node. If the database is managed by Oracle Clusterware, broker does not open any of the stored in the specified path using the default file names. If the former primary database cannot be reinstated automatically, you can manually reinstate it using either the DGMGRL REINSTATE command or Cloud Control. The 3. isolated. pre-callout configuration script and post-callout configuration script. Please contact us at contactus@smarttechways.com. For example: Fast-start failover occurs if both the observer and the target standby database lose connection to the primary database for the period of time specified by the FastStartFailoverThreshold configuration property. If failover occurs to a logical standby database, all physical and snapshot standby databases will be disabled by the broker. command does not have a network connection to the primary database. To help you select an appropriate switchover or failover target, use the following DGMGRL commands which perform checks on the database to determine its readiness to complete a role change. If the database is not enabled, you will not be able to perform a failover to this database. That is, if the observer is connected to any instance in the Oracle RAC, all instances will show a value of YES. The My Oracle Support note 1625597.1 at http://support.oracle.com for information about compatibility requirements between the observer and DGMGRL, Starting Multiple Observers on a Data Guard Broker Configuration. See Manual Failover for information about manual failover. The minimum value is 100 milliseconds. Database dismounted. The ObserverOverride configuration property, when set to TRUE, allows an automatic failover to occur when the observer has lost connectivity to the primary, even if the standby has a healthy connection to the primary. distance. Disabling fast-start failover with the FORCE option when connected to the target standby database guarantees that fast-start failover will not occur. fast-start failover when: A network outage isolates the primary database from the observer and the target standby database before conditions exist that warrant a failover. Theoretically, this method can be used when a data guard failover occurred between the primary and standby database, but not a switchover. Monitor the environment to ensure the primary database is available. Use broker configuration properties to set the time taken to detect a from another DGMGRL session. Performing a Manual Failover Task 1: Determine Which of the Available Standby Databases is the Best Target for the Failover, Performing a Manual Failover Task 2: Start the Failover, Performing a Manual Failover Task 3: Reset the Protection Mode, Performing a Manual Failover Task 4: Re-establish a Disaster-Recovery Configuration. DG BrokerDG BrokerData Guard BrokerOracleDGRMAN Duplicate . The logs also contain other details about the actions that will be performed in case of a failover. This property allows you to specify a priority ordered create the directory specified by the DG_ADMIN environment variable and In a Managed Instance with multiple databases in Azure we can have high availability. We'll leave the other properties at their default values for the walkthrough, but you should become familiar with all of the Broker config and database properties. fast-start failover operation, the observer checks if a fast-start failover configuration. Manual failover to the fast-start failover target can be performed without receiving an acknowledgement from the observer. Overall commit latency is increased by the round-trip network latency. See Oracle Data Guard Concepts and Administration for more information on using the ALTER SYSTEM FLUSH REDO statement. These are the actions the broker performs after you start a switchover. have received all the redo data the primary has generated in order for automatic failover to The master observer never waits for the threshold to expire to perform a fast-start failover in the following situations: If the master observer determines that any of the user-configurable conditions has been detected, then it attempts a fast-start failover. In a Data Guard environment primary database is open in read write mode and the standby database in read only mode for reporting purpose. Then, on the Fast-Start Failover Configure page, select the standby database that should be the target of a failover. FastStart Failover Ensues: Disaster strikes the primary database and its network connections to both the observer and the target standby database are lost. By choosing the standby database with the least amount of unapplied redo, you can minimize the overall time it takes to complete the switchover operation. Oracle 12c-Step by Step Manual Data Guard Switchover, Manual Upgrading Oracle Database From 11.2.0.4 to 12.2.0.1, Automatically Terminated The Blocking Session By Setting MAX_IDLE_BLOCKER_TIME, Apply Patching On Oracle 21c Database Release Update 21.7.0.0.0, Oracle 21c Point In Time Recovery of Pdb Database, Oracle 21c Cloning a PDB Database Using Sqldeveloper Tool. See Oracle Enterprise Manager Command Line Interface. Immediate Failovers in Configurations Using Cascaded Standbys. DG_BROKER_START is set to TRUE and DG_BROKER_CONFIG_FILEn are set correctly SQL> sho parameter broker See Choosing a Target Standby Database for helpful advice. configuration file, such as START OBSERVING, In a separate terminal session, verify the configuration. the ObserverPingRetry and ObserverPingInterval properties to achieve learning with R and Python are also covered in this step-by-step tutorial. SET ObserverConfigFile used to specify a customized observer configuration file. If these parameters are modified outside of Broker, it raises a warning. automatic failover feature in configurations set up for zero data loss protection at any The standby database must be re-created or reinstated before it can serve as a standby for the new primary database. After a switchover completes, the broker preserves the overall Oracle Data Guard protection mode as part of the switchover process by keeping the protection mode at the same protection level (maximum protection, maximum availability, or maximum performance) it was at before the switchover. Unlike the primary / standby interconnect, where bandwidth and latency are determining performance factors, the observer requires very little network bandwidth and is not overly latency sensitive, allowing the it to be placed practically anywhere a reliable connection is available. expires. The observer's main purpose is to enhance high availability and lights out computing by reducing the human intervention required by the manual failover process that can add minutes or hours to downtime. The following is an example of querying the V$FS_FAILOVER_STATS view: Disabling fast-start failover prevents the observer from initiating a failover to the target standby database. If the configured data loss guarantee cannot be upheld, Steps to Create a Physical Standby Databa se 3 -3 Preparing the Primary Database 3 -4 FORCE LOGGING . the primary database that failed or took longer than the time If the former physical standby database was running with real-time query enabled, the new physical standby database will run with real-time query enabled. file (fsfo.dat). If the observer finds that the database is no longer the primary, it will attempt to reinstate it as the failover target standby. For more details about managing Redo Apply services using properties, see Managing Log Apply Services. Stop the observer using the DGMGRL STOP OBSERVER command. The broker verifies the state and status of the databases to ensure that the switchover transitioned the databases to their new role correctly. If a failure occurs once a reinstatement operation (automatic or manual) is underway, the broker logs the appropriate information in the broker configuration files and broker log files. Switchover and Manual Failover for more information about switchovers and manual failovers, respectively. SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY; Broker maintains these parameters by issuing ALTER SYSTEM commands as appropriate during role transitions, database startup/shutdown, and other events. Remember to check Flashback Database history before aborting the primary. The terminal session will appear to hang at this point. Among many benefits of using this utility, I highlight that while using it, it will not need manual intervention to recover the databases or eventually a switchover in case the primary database becomes unavailable. You can optionally indicate the database health conditions that should cause fast-start failover to occur. When a fast-start failover occurs because either a user configurable fast-start failover condition is detected or an application initiates a fast-start failover by calling the DBMS_DG.INITIATE_FS_FAILOVER function, the former primary database is always shut down and never automatically reinstated.