), The RedoRoutes property on a far sync instance if it is being used to receive redo from the primary database and ship redo to the target standby database, The standby database that is the target of fast-start failover, A far sync instance if it is being used to receive redo from the primary database and ship redo to the target standby database, Unless the conditions listed in Performing Manual Role Changes When Fast-Start Failover Is Enabled have been met, To a standby database that is not configured as the fast-start failover target. 2. redo generation on the primary database will be stalled. 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 . After Fast-Start Failover: The fast-start failover has completed and the target standby database is running in the primary database role. Table 6-2 FS_FAILOVER_STATUS Column of the V$DATABASE View. We will create 4 SRLs starting with group# 11. distance. When a fast-start failover occurs because either a user configurable fast-start failover condition is detected or an application initiates a fast-start failover by calling the DBMS_DG.INITIATE_FS_FAILOVER function, the former primary database is always shut down and never automatically reinstated. If you want the broker to skip this viability check of bystander standby databases during a complete failover, thus decreasing the overall failover time, set the BystandersFollowRoleChange configuration property to NONE. To change the FastStartFailoverTarget property to point to a different standby database, disable fast-start failover, set the FastStartFailoverTarget property, and reenable fast-start failover. The time interval specified by the FastStartFailoverThreshold property is ignored if the master observer detects that a user-configurable condition has occurred or if a fast-start failover has been requested by the DBMS_DG.INITIATE_FS_FAILOVER function. A simple example for *nix is provided below that will work with both releases. To determine if the configuration is ready for fast-start failover to occur, issue the DGMGRL SHOW DATABASE command, or query the V$DATABASE view on either the primary or target standby databases. db1_a: Alias to connect to the dynamic Data Guard service on database "a", db1_b: Alias to connect to the dynamic Data Guard service on database "b", db1_a_static: Alias to connect to the static Data Guard service on database "a", db1_b_static: Alias to connect to the static Data Guard service on database "b". The master observer waits the number of seconds specified by the FastStartFailoverThreshold configuration property before attempting a fast-start failover when the primary database has crashed or has lost connectivity with the observer, as in the following situations: The primary database loses its connections with both the observer and target standby database. This is to ensure that the service definition gets propagated to the physical standby database via the redo stream and thus allows for the service to be started on the physical standby database. It will return PHYSICAL STANDBY, Displays if the standby database's redo applied point does not lag the primary database's redo generation point by more than the number of seconds specified by the FastStartFailoverLagLimit configuration property and the configuration is operating in maximum performance mode. If the credentials cannot be obtained, then the attempted command fails (but only for the broker configuration whose credentials have not been obtained). The minimum value is 100 milliseconds. crash, data in this file can be used to restart the observer to the Flashback Database is a continuous data protection (CDP) solution integrated with the Oracle Database. (It is permissible to change the RedoRoutes property on all standby databases including target standby databases. The master observer uses the value specified by either the DGConnectIdentifier or ObserverConnectIdentifier database properties to connect to the primary and fast-start failover target standby databases. Fast-start failover is inhibited in this case. For zero data loss in maximum availability mode, the FastStartFailoverLagLimit property must be set to zero. If the protection mode was at maximum protection, it is reset to maximum performance. If the observer is unable to regain a connection to the primary database within the specified time, and the target standby database is ready for fast-start failover, then fast-start failover ensues. DGMGRL> show configuration Configuration - CDB01_fraad1_CDB01_fraad3 Protection Mode: MaxAvailability Members: CDB01_fraad1 - Primary database CDB01_fraad3 - (*) Physical standby database All Data Guard environments should enable force logging at the database level in order to guard against nologging tablespaces from being added. For example: In the following example, assume the network between the primary database and the observer has failed. DG_BROKER_START is set to TRUE and DG_BROKER_CONFIG_FILEn are set correctly SQL> sho parameter broker If the primary database has multiple standby databases, then you can specify multiple fast-start failover targets, using the FastStartFailoverTarget property. Logical standby databases that are disabled during failover can be reinstated. DGMGRL. Stops Redo Apply or SQL Apply on the standby database immediately, without waiting until all available redo data has been applied. Broker will set the primary to use asynchronous log transport by default. Step 4: Enable Fast-Start Failover Now we are ready to enable FSFO: DGMGRL> enable fast_start failover; Enabled in Zero Data Loss Mode. It is instructive to watch the alert logs on both databases as well as the observer log after aborting the primary to gain insight into what happens during FSFO failover. The standby VM (myVM2) has the Oracle software installed only. This section describes how to stay on top of your FSFO environments. the observer configuration file is observer.ora. Perform SWITCH LOGFILE if necessary. In such cases, the failed primary database is reinstated as a physical standby database. Broker maintains these parameters by issuing ALTER SYSTEM commands as appropriate during role transitions, database startup/shutdown, and other events. This prevents a "split brain" condition if a failover occurs since none of the changes made to the isolated primary can be made permanent. Displays when the primary and target standby databases are synchronized and the configuration is operating in maximum availability mode. Oracle Data Guard helps you change the role of databases between primary and standby using either a switchover or failover operation. You will have to reinstate or re-create (see Reenabling Disabled Databases After a Role Change) the standby databases after failover has completed. It shuts down or stalls because it is likely a failover has occurred. configuration named ConfigurationSimpleName. When restarting the databases, you may restart them in any order. The following sections describe these topics: Prerequisites for Enabling Fast-Start Failover, Viewing Fast-Start Failover Configuration Statistics and Status, Performance Considerations for Fast-Start Failover, Reinstating the Former Primary Database in the Broker Configuration, Shutting Down Databases In a Fast-Start Failover Environment. If fast-start failover is disabled, then manual failover may still be possible. If there are multiple observers, then only one of them is the master observer. If multiple observers have been started for the configuration, then be sure to specify the name of the observer whose environment is to be patched (STOP OBSERVER observer-name). FastStartFailoverLagLimit property. connectivity with target standby. You must In maximum performance mode, the ability to automatically failover is restored prolonged stall, either the observer or target standby database To start the observer with DGMGRL, issue the following Use broker configuration properties to set the time taken to detect a LinkedIn:https://www.linkedin.com/in/hari-prasath-aa65bb19/ The FastStartFailoverLagLimit configuration property is only used by the broker when enabling fast-start failover for configurations operating in maximum performance mode. For example: Using DGMGRL, you can do this by examining the output of the SHOW CONFIGURATION LAG. If you are not using Oracle Clusterware or Oracle Restart, then you must create static service names so that the observer can automatically restart a database as part of reinstatement. Check the database role,open_mode in standby server. In this mode you will need to consider how much data loss is acceptable in terms of seconds and set the FastStartFailoverLagLimit configuration property accordingly. A manual failover is already in progress. command on the observer computer: The observer is a continuously executing process that is For example, if the limit specified is 30 seconds (the default), FSFO guarantees that all transactions that committed prior to 30 seconds ago are preserved during failover. If these parameters are modified outside of Broker, it raises a warning. Figure 6-1 Relationship of Primary and Standby Databases and the Observer. multiple, inexpensive servers is the basis for the failover and other fault-tolerance features that RAC provides. (Note: 11.1.0.7 adds the StaticConnectIdentifier Broker database property to allow you to specify a different service name.) Commands For Managing Observers on Multiple Configurations. Enabling Fast-Start Failover describes how to start observers as a part of the step-by-step process to enable fast-start failover. In this case, the FS_FAILOVER_STATUS and FS_FAILOVER_OBSERVER_PRESENT columns will appear as shown in the following table and fast-start failover will not occur: Oracle Database Reference for more information about the V$DATABASE view. The target standby database when it does not have connectivity with the primary database, fast-start failover is disabled only on the target standby database. configuration property. Data Guard Switchover/failover to standby The standby database will be activated to serve as the primary database at some point in its life cycle. They may be reinstated if Flashback Database is enabled on those databases. Once an immediate failover is started, the broker: Verifies that the target standby database is enabled. To disable fast-start failover, use the Fast-Start Failover wizard in Cloud Control or the DGMGRL DISABLE FAST_START FAILOVER [FORCE] command. The master observer cannot connect to the target standby database, What Happens if the Observer Fails? databases (PDBs) on any of the instances. Initiate the switchover on the primary database PRIM: Relationship Between Primary, Target Standby, and Observer During Fast-start Failover. Immediate Failovers in Configurations Using Cascaded Standbys. Now it will return PRIMARY. observers for a single Data Guard configuration. Create a pre-callout script, or a post-callout script, or both. This walkthrough uses Maximum Availability mode to achieve "zero data loss". This is the recommended method for disabling fast-start failover. These are some points to consider before you begin a switchover. By default, the observer will initiate failover to the target standby if and only if ALL of the following are true: Oracle Database 11g Rel 1 introduced user configurable failover conditions that can trigger the observer to initiate failover immediately. ERROR: Unable to verify the graphical display setup. After a failover, the broker publishes Fast Application Notification (FAN) events. The pre-callout script On the Data Guard Failover Confirmation page, specify the type of failover that you want to perform: Complete: All available redo is applied on the standby database. Note that enabling FSFO does not make the configuration ready for automatic failover - that requires an observer, which we'll get to next. connection, or the database on which you issued the disable fast-start failover For example, if all your physical standbys are also unavailable, then failing over to a logical standby is your only choice. Monitor the environment to ensure the primary database is available. the primary role, use the PreferredObserverHosts If a fast-start failover was initiated because the primary database had crashed or lost connectivity with the master observer and target standby database, then the master observer automatically attempts to reinstate the former primary database as a standby database, if the FastStartFailoverAutoReinstate configuration property is set to TRUE. In a Data Guard environment primary database is open in read write mode and the standby database in read only mode for reporting purpose. If the configured data loss guarantee cannot be upheld, The broker verifies the state and status of the databases to ensure that the switchover transitioned the databases to their new role correctly. The string "NONAME" cannot be used as an observer name. upheld. Displays only on the target standby database when it is SYNCHRONIZED with or is TARGET UNDER LAG LIMIT of the primary database, has connectivity to the observer, but the primary database does not have a connection to the observer. database that has the least amount of unapplied redo (smallest apply lag). enabling fast-start failover. For more information, see START OBSERVER IN BACKGROUND. You have done a failover to your Standby database so it becomes the new Primary. Stores the observer runtime data file and observer configuration file in When you execute commands that affect multiple observers, if you have not specified a name and location for the observer configuration file, then broker searches the current working directory for a file named observer.ora. In this case, no attempt is made to transmit any unsent redo from the far sync instance to the target physical standby prior to converting the physical standby into a primary database. In this mode, no actual changes are made to your Broker configuration. Figure 6-1 shows the relationships between the primary database, target standby database, and observer during fast-start failover: Before Fast-Start Failover: Oracle Data Guard is operating in a steady state, with the primary database transmitting redo data to the target standby database and the observer monitoring the state of the entire configuration.