configuration. Alternatively, use the RedoRoutes property to configure the redo transport mode for the target standby and the database currently in the primary role. MASTEROBSERVERHOSTS, DGMGRL reports an error if the the names of the scripts created in the previous step. Steps that require the primary to be in a mounted (not open) state are grouped together in the section below entitled Steps Requiring a Bounce of the Primary. The guide makes few assumptions about your existing environment and includes examples for creating a physical standby database and Data Guard Broker configuration. SUSPENDED is cleared when connectivity with the primary database is restored. While Oracle 11g's Data Guard definitely protects a database when the entire production site is lost via its failover capabilities, it's still necessary for an Oracle DBA to intervene to complete the failover process. Use Cloud Control or DGMGRL to perform either a complete (recommended) or an immediate failover. Fast-start failover will not occur unless all instances comprising the Oracle RAC primary database are perceived to have failed. the primary role, use the PreferredObserverHosts For Oracle Database Release 12.2 and higher, Oracle Enterprise Manager Cloud Control (Cloud Control) supports configuring multiple observers using the Enterprise Manager Command Line Interface (EM CLI). File. The subcommands for this verb include start, stop, setMaster, show, and delete_alternate_observer. Oracle FAN with Oracle Data Guard but without using Oracle Grid/ RAC irrespective of its content, indicates that the script executed successfully. How To Setup Dataguard Broker Configuration (DG Broker) In 19c Click Failover. FAN events are published using Oracle Notification Services (ONS) for all Oracle integrated database clients in Oracle Database 12c and later. 3. 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. Failover automation ensures a seamless transition from the primary database to a synchronized standby database in cases of failure, while ensuring database availability by replaying uncommitted in-flight transactions. If the agent is not It is also supported for fast-start failover to physical standbys in maximum availability data protection mode. Enabling Fast-Start Failover Task 1: Determine Which of the Available Standby Databases is the Best Target for the Failover, Enabling Fast-Start Failover Task 2: Specify Target Standbys with the FastStartFailoverTarget Configuration Property, Enabling Fast-Start Failover Task 3: Determine the Protection Mode You Want, Enabling Fast-Start Failover Task 4: Set the FastStartFailoverThreshold Configuration Property, Enabling Fast-Start Failover Task 5: Set Other Properties Related to Fast-Start Failover (Optional), Enabling Fast-Start Failover Task 6: Enable Additional Fast-Start Failover Conditions (Optional), Enabling Fast-Start Failover Task 7: Using DGMGRL or Cloud Control, Enabling Fast-Start Failover Task 8: Start the Observer, Enabling Fast-Start Failover Task 9: Verify the Fast-Start Failover Environment. Rather, fast-start failover will be enabled in accordance with the current protection mode. created under this directory by DGMGRL will also have the same permissions. In a Managed Instance with multiple databases in Azure we can have high availability. if the observer is not running, The master observer and the target standby database are inconsistent with regard to the current state of the broker configuration, If the protection mode is maximum availability or maximum protection and the target standby database was not synchronized with the primary database at the time the primary database failed, If the protection mode is maximum performance and the apply point of the target standby database lags the redo generation point of the primary database by more than the amount specified by the FastStartFailoverLagLimit configuration property at the time the primary database failed. For example: Using DGMGRL, you can do this by examining the output of the SHOW CONFIGURATION LAG. In cases where Broker can be configured to initiate failover on any of the following conditions. Disable fast-start failover using the DGMGRL DISABLE FAST_START FAILOVER command. In an environment where there are multiple observers configured, stopping the master observer is not allowed unless it is the last running observer. Open another prompt and connect to SQLPLUS: Performing failover : Step 1: Check Standby Database role. Aug 2022 - Present6 months. Each group that you define must have at least one broker configuration. If you cannot tolerate any loss of data, then ensure that the configuration protection mode is set to maximum availability or maximum protection. Your email address will not be published. Make sure the last redo data transmitted from the Primary database was applied on the standby database. The remaining observers are called backup observers. See Reenabling Disabled Databases After a Role Change for more information. How To Use Local Data Processing and Oracle Data Guard for Source Use Recovery Manager (RMAN) to back up the PeopleSoft database on a regular backup schedule. This support note is available at http://support.oracle.com. For systems with multiple RAID controllers, consider creating SRLs such that their IO is balanced across the controllers. This walkthrough uses Maximum Availability mode to achieve "zero data loss". Switchover/Failover operation in 2-node RAC and 2-node DATAGUARD In the following example, a service named sales is configured to be active in the PHYSICAL_STANDBY role on the primary database NORTH. It is very much useful, when the organization has multiple standby sites. FSFO builds upon a number of other Oracle technologies and features such as Data Guard, Flashback Database, and Data Guard Broker. isolated. The following is an example of setting the LogXptMode property: Alternatively, use the RedoRoutes property to set the redo transport mode for the target standby and database that is currently in the primary role. These are some points to consider before you begin a switchover. However, there may be exceptions to the recommendation to choose a physical standby database as the target standby database. One is the master What is true about data guard set up with fast-start failover (FSFO) in Oracle Cloud Infrastructure (OCI)? 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. If the value is zero, the standby must database is in the primary role. Enabling fast-start failover and starting an observer process involves the following tasks. database that has the least amount of unapplied redo (smallest apply lag). specified, the file is stored in an appropriate directory under the broker's milliseconds and that of ObserverRetryCount is 10. The required attributes vary depending on your configuration (including whether your environment is Oracle RAC-based or single-instance). So SALESRW will start on CHICAGO (which is now the primary) and SALESRO will start on BOSTON (which is now the physical standby). In the media recovery phase, Flashback Database applies redo to bring the database up to the standby_became_primary_scn. SHOW OBSERVERS [FOR fg_group_name ] shows information about observers for all configurations in the specified group. Disaster Recovery with Oracle Data Guard - online presentation broker does not allow the primary database to commit transactions until it has regained standby database, host, or network failure, etc.). You can query the V$FS_FAILOVER_STATS view on the primary database to display statistics about fast-start failovers that have occurred on the system. In case of worst situation with data guard primary database, or not available for production than we can activated standby database as a primary production database. Database services can be configured to be active in specific database roles on Oracle RAC databases and on single-instance databases managed by Oracle Restart. the primary and target standby databases. The primary database can be opened even if there is no acknowledgement from the observer or target standby. Slightly less critical than making sure you've got a good primary is making sure the failed primary can be automatically reinstated. In these sample commands, the ellipse () signifies any other add service options you wish to supply. The physical and snapshot standby databases will have to be re-created from a copy of the new primary database. In such a case, no attempt is made to transmit any unsent redo from the cascader to the terminal standby. Starting Observers as Background Processes. failure on the primary database. If there are multiple observers, then only one of them is the master observer. SQL> startup ORACLE instance started. In this case, the primary database stalls and prevents any further transactions from Bounce your database and verify database name its open mode and its role: SQL> shutdown immediate; ORA-01109: database not open Database dismounted. PRIM>STARTUP MOUNT; (This is useful because the name defined in the metadata may contain whitespace and international characters, which the observer configuration file does not allow.). Choose a value high enough to avoid false disconnects from intermittent network trouble. To reenable broker management of these databases, you must reinstate or re-create the databases using one of the following procedures: If a database can be reinstated, the database will show the following status: Reinstate the database using the DGMGRL REINSTATE DATABASE command or the reinstate option in Cloud Control, as described in How to Reinstate a Database. FAN server-side callouts can be configured on the database tier. The minimum value of ObserverPingInterval is 100 Execute the following on primary database NORTH: Execute the following on the physical standby database SOUTH: If the broker now performs a switchover or failover, it automatically starts the SALES service on the correct database, based on the database's role. See Sources of Diagnostic Information for details about the broker's drc* log files. In Oracle RAC configurations, the Inaccessible Logfile and Stuck Archiver health conditions may only be applicable to a single instance. Configure the protection mode. select name,open_mode,database_role from v$database; Note: change tracking enabled, broker enables block change tracking on the new This document describes how to setup clients to connect to Data Guard databases (primary and standby) and configure automatic client failover such that in case there is role change due to switchover or . Disabling Fast-Start Failover Using Cloud Control. See Reenabling Disabled Databases After a Role Change. This property allows you to specify a priority ordered If this is an Oracle RAC physical standby database managed by Oracle Clusterware, then the broker directs Oracle Clusterware to restart the new standby database. To start an observer as a background process, use the DGMGRL 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. The v$database view has has columns specifically for monitoring FSFO status. Before beginning a failover, first determine that there is no possibility of recovering the primary database in a timely manner, and ensure that the primary database is shut down. flashback logs on that database. In maximum availability mode, set the LogXptMode database property for both the primary and target standby databases to SYNC or FASTSYNC. For example: Scenario 6: Enabling Fast-Start Failover and Starting the Observer. A switchover guarantees no data loss and is typically done for planned maintenance of the primary system. When the primary database and the target standby database regain network connectivity, the broker will disable fast-start failover for the entire broker configuration. Check the Undo tablespace Usage in Oracle, Exclude/Include option in EXPDP and IMPDP Datapump, Missing Dependencies Python Core / win32api, Stop the EXPDP/IMPDP Datapump Job in Oracle, Find the temp usage by sessions in Oracle, Create & grant permission to directory in Oracle, Check the Patch Applied to the Oracle Database. To specify which observer can be a master observer when a database is in Setting it to 'FALSE' leaves the database open and stalled until it is terminated or signaled to proceed in the event a failover did not take place (e.g. the observer was killed after the stall began, but before the failover timeout had elapsed). Determines whether or not any standby databases that did not participate in the failover operation have applied redo data beyond the new primary database, and thus need to be disabled. This property specifies the amount of data, in seconds, that the target standby database can lag behind the primary database in terms of redo applied. If Flashback Database history is insufficient, the observer will not be able to reinstate and you will have to manually reinstate from backup or by primary duplication. See the "DISABLE FAST_START FAILOVER" command in Oracle Data Guard Command-Line Interface Reference for more information. Sets up redo transport from the new primary to the other members of the configuration, Starts Redo Apply services on the new standby, Ensures the other standbys in the broker configuration are viable to the new primary, Integrates with Oracle Clusterware and Oracle Global Data Services (GDS) to ensure that the proper services are started after a role change. property. If fast-start failover is already enabled, the If the client uses remote ONS subscription, the client must specify the hostname and port of the ONS daemon(s) of the primary database and each standby database. 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. Verify the standby database instance is mounted. 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 . In addition, a logical standby database may contain only a subset of the data present in the primary database. See theFlashback Database section above for information on storage requirements. ensure that it has the required permissions. miliseconds. For this build, we will use a single physical standby database. Manual failover to the fast-start failover target can be performed without receiving an acknowledgement from the observer. During a complete failover, the broker performs the failover steps described in How the Broker Performs a Complete Failover Operation. The value specified for either of these properties should allow the master observer to connect to any instance of an Oracle RAC database. process. You must determine which available standby databases should be targets for failover. In a DataGuard environment when the Primary instance fails you need to go through the Failover and Reinstate processes in order to restore the database service, as described in the documentation: Changes a standby database to the primary role in response to a primary database failure. US Coast Guard Auxiliary. Let's run the command on the primary database to validate if the environments are ready for the role transition : JITPRD> alter database switchover to JITSDB verify; alter database switchover to JITSDB verify * ERROR at line 1: ORA-16475: succeeded with warnings, check alert log for more details broker configuration, you must connect through another DGMGRL client To verify the readiness of the fast-start failover configuration, issue the DGMGRL SHOW CONFIGURATION VERBOSE command or the SHOW FAST_START FAILOVER command on the primary database. You can start the observer before or after you enable You must database (if real-time query is enabled). The broker automatically reenables the database as part of reinstating it. DGMGRL can be used to manage multiple observers in a group of broker configurations. The default name for Use the EMCLI verb dg_configure_observers. A normal shutdown prevents a fast-start failover until the primary database and standby database are connected and communicating again. Note the primary and target standby must have connectivity for this command to complete successfully. RAM). Staff support, hardware and software, security (both software and site), network connections, and bandwidth should be equivalent at both sites. The following assumes that the standby host has been setup according to Oracle's recommendations and that the operating system, accounts, security, resource limits, directory structure, etc. They rely on Oracle Data Guard for high availability databases, with a standby database running in a different availability zone. LGWR is unable to write to any member of the log group because on an I/O error. the preferred method for starting an observer. The new primary database is opened in read/write mode and redo transport services are started. 4. No instances are shutdown when doing a failover, if the target standby database is either a physical or logical standby. Then set the configuration protection mode to maximum availability. Starting with 11 is purely cosmetic - it allows new ORL groups to be added later while keeping their group# in the same sequence as the existing ORLs. A Senior Engineer's Guide to the System Design Interview 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). Do not use Shared Server (formerly MTS) for Data Guard. The default value is 30 seconds and the lowest possible value is 5 seconds. These conditions are described in the following table: Dictionary corruption of a critical database. This configuration property causes the former primary database to be automatically reinstated if a fast-start failover was initiated because the primary database was either isolated or had crashed. The most common problems are mismatched Data Guard protection modes and LogXptMode properties and forgetting to enable Flashback Database on the primary or standby. Switching over to a logical standby database results in the snapshot and physical standby databases in the broker configuration being disabled by the broker, making these databases no longer viable as standby databases. occur. become the master observer. Broker keeps its configuration details in flat file. automatic failover feature in configurations set up for zero data loss protection at any Failing over the database won't do much good if applications and other database clients don't know where the primary went. If the Broker configuration is changed to make a bystander the new failover target (probably a good idea if the failed database will be down for a while), the observer will not automatically reinstate the former primary because it is no longer part of the FSFO configuration. Except for testing purposes, it is not recommended that you start more than one observer on the same host for a Data Guard broker configuration. configuration property. This can be done regardless of whether the failover was done to a physical, logical, or snapshot standby database. If the primary database does not have connectivity with the target standby database, fast-start failover remains enabled on the target standby database and the observer may still attempt a fast-start failover if conditions warrant a failover. You can optionally indicate the database health conditions that should cause fast-start failover to occur. property. only. Other members of the configuration will receive redo from the designated redo source based on the new primary. If there are physical or snapshot standby databases in the configuration and the switchover occurs to a logical standby database, you need to re-create those databases from a copy of the new primary database and then reenable those databases, as described in Reenabling Disabled Databases After a Role Change. disable fast-start failover with the FORCE option on the Logical standby databases that are disabled during failover can be reinstated. The SHOW CONFIGURATION command will show you which databases can be reinstated and which databases must be re-created. In the event of a By default the file is named fsfo.dat and is created in the working directory where the observer is started. Improper Oracle Net configuration is a leading cause of reported FSFO issues. If there is only one standby database in the configuration, you can skip this step and continue with Task 3. As shown in the table, fast-start failover can be enabled in maximum availability Now we will see a step-by-step approach to perform a switchover between the primary and the logical standby database: . Only two databases, the primary and the failover target, can be in the FSFO configuration at any given time. Remember to check Flashback Database history before aborting the primary. November 20, 2009. If any errors occur during either conversion, the broker stops the switchover. It has two parts in the following order: Configuration declaration this section is mandatory. If it reconnects to the primary database before the standby agrees to fail over, then the master observer will stop attempting to initiate a fast-start failover. The same thing happens if a shutdown and startup of either database occurs - the service that is started is the one that matches the role of the database being started. The observer is the key element that separates Data Guard failover from its pre-FSFO role as the plan of last resort to its leading role in a robust high availability solution. You can disable fast-start failover if necessary, by using the FORCE option. Fast-Start Failover in Oracle 11g Data Guard - Database Journal You can use this information to identify ahead of time any redo transport configurations that would be incorrect after a role change, including any standbys that will not receive redo because the RedoRoutes property was not configured correctly. Note that these properties only affect whether primary shutdown and automatic reinstatement are performed if a fast-start failover occurs because the primary crashed or was isolated from the observer and target standby database. The ObserverPingInterval connectivity with target standby. If block change tracking is enabled on the primary, and the target 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. If the primary and target standby databases do not have network connectivity or if the database to which you are connected does not have network connectivity with the primary database, consider using DISABLE FAST_START FAILOVER with the FORCE option. is only possible when the configured data loss guarantee can be It behaves similarly to START OBSERVING and STOP OBSERVING to operate on all the configurations defined in the observer configuration file. This specifies how often the observer establishes a new connection to the primary database. The broker disables all of the physical and snapshot standby databases in the configuration. Most in-progress failures cannot be restarted (for example, archived redo log file corruption on the primary database). The FS_FAILOVER_OBSERVER_PRESENT column displays YES for the target standby database. Use broker configuration properties to set the time taken to detect a This is true regardless of the settings for the FastStartFailoverPmyShutdown and FastStartFailoverAutoReinstate configuration properties. If Flashback Database fails, automatic reinstatement stops and you will have to perform a manual SCN-based recovery to the standby_became_primary_scn and complete the reinstatement. SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE FINISH; For example, if the old standby was a physical or snapshot standby, then the old primary must be re-created as a physical standby. All standbys other than the failover target are considered bystanders (v$database.fs_failover_status = 'BYSTANDER'). If a single-instance primary database (either Oracle RAC or non-Oracle RAC), or if all instances of an Oracle RAC primary database fail, the observer attempts a fast-start failover. Physical Standby Database SWITCHOVER & FAILOVER Operations We can always fail over to it or have it happen automatically if for some reason the primary Managed Instance has [] After fast-start failover is enabled and up to four observers are started, one observer is nominated as the master observer that continuously monitors the environment to ensure the primary database is available. Fast-start failover is enabled, but this standby database is not the target of the fast-start failover. The column value for V$DATABASE.FS_FAILOVER_STATUS will be SYNCHRONIZED in a configuration operating in maximum availability mode, and it will be TARGET UNDER LAG LIMIT in a configuration operating in maximum performance mode when ready to fast-start failover. 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. After a role change, the naming service can be updated with the new primary's address. The time interval starts when the observer first loses its connection to the primary database. Some properties have changed between those releases. Now it will return PRIMARY. If there is more than one standby database in the configuration, you must explicitly set the FastStartFailoverTarget property on the primary database to name one or more candidate target standby databases. Make sure that your OS environment on the standby is setup. For more details about managing redo transport services using database properties, see Managing Redo Transport Services. In addition, the primary database will shut down if it perceives a loss of connectivity for a period longer than FastStartFailoverThreshold seconds, if the FastStartFailoverPmyShutdown configuration property is set to TRUE. A fast-start failover occurred because a user-configurable condition was detected or was requested by an application by calling the DBMS_DG.INITIATE_FS_FAILOVER function. However, if you want the observer to reconnect to the primary database periodically as a means of testing the health of the network connection to the primary, then use the ObserverReconnect configuration property. For each broker configuration on which one or more You can upgrade the protection mode later, if necessary, as described in Setting the Protection Mode for Your Configuration. Add the SRLs. Issue the following SRVCTL commands: Now the correct services are running on the correct databases. Data Guard Failover Options - dba-oracle.com observers for a single Data Guard configuration. See Choosing a Target Standby Database for helpful advice. Getting the Oracle Net configuration right is one of the key factors in a successful FSFO deployment. A database in the primary role will not open until it has verified with the observer that it is still the primary. Oracle Data Guard is a solution provider to businesses by offering data protection and its disaster recovery along with its high availability. observers are registered, a directory named If errors occur during the disable operation, the broker returns an error message and stops the disable operation. The behavior of the broker if the master observer fails depends on whether the broker configuration has one observer or multiple observers.