data guard failover steps

The commands that can be executed for a group of configurations (as declared in an observer configuration file) are as follows. observer as a foreground process. You can start, stop, and show observers for a group of configurations. Provides an automatic failover environment Click Failover. Once an observer is started, no further user interaction is required. To start a switchover using Cloud Control, select the standby database that you want to change to the primary role and click Switchover. The broker allows an immediate failover to proceed even if there are errors present on the standby database that you selected to participate in the failover. See Reenabling Disabled Databases After a Role Change. Switchover/Failover operation in 2-node RAC and 2-node DATAGUARD For example: Scenario 6: Enabling Fast-Start Failover and Starting the Observer. SQL Apply on all other bystander standby databases automatically begin applying redo data received from the new primary database. On the Oracle Data Guard Overview page, click Database must be reinstated. When the observer loses its connection to the primary database for a period of time greater than that specified by the FastStartFailoverThreshold property, it attempts a failover to the standby database. PRIM>STARTUP MOUNT; 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. To achieve 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. pre-callout configuration script and post-callout configuration script. When the configuration has only one registered observer, if the primary and target standby databases stay connected but the connection to the observer is lost, then the broker reports that the configuration is not observed. Stop the observer using the DGMGRL STOP OBSERVER command. receives redo data from a far sync instance. However, failover is attempted if the ObserverOverride configuration property is set to TRUE. 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. To stop the observer when fast-start failover is disabled, the primary database must be running. There are normally two situations when this operation will be performed: a planned outage for maintenance of the primary database or disaster recovery. If the switchover occurs to a physical standby database, and the former primary 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. As shown in the table, fast-start failover can be enabled in maximum availability You can also reinstate bystander standby databases that were disabled during a failover operation. The subcommands for this verb include start, stop, setMaster, show, and delete_alternate_observer. Fast-start failover can be used only in a broker configuration and can be configured only through DGMGRL or Cloud Control. Data Guard Failover Options - dba-oracle.com Verify dmon process is running and broker parameters viz. It wouldn't be much of a test if we didn't verify that our durability constraints were being met, so let's make a change on the primary and see if it survives the failover. MASTEROBSERHOST TO command. The ObserverReconnect configuration property specifies how often the observer establishes a new connection to the primary database. To restore your original disaster-recovery solution after switchover to a logical standby database or after failover to any standby database, you may need to perform additional steps. Thus, the validity of the values of these properties is not verified until after the switchover. You can enable fast-start failover from any site while connected to any database in the broker configuration. Complete Failovers in Configurations Using Cascaded Standbys. Most of the network services used in a FSFO environment may use dynamic registration, but to enable Broker to restart instances during role transitions or during reinstatement after a failover, you must define a static service named db_unique_name_dgmgrl. directory has the same permissions as its parent directory. Be sure to include the Data Guard listener in the local_listeners database parameter. 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. The minimum detection time is 6 seconds, which is the default The foundation of FSFO is Data Guard - a primary and at least one standby. Broker keeps its configuration details in flat file. Ensure SPFILE is used SQL> sho parameter spfile 2. file also declares broker configurations and defines configuration If the target is a snapshot standby database, the broker first converts the database to a physical standby database. See Prerequisites for more information. The value specified for either of these properties should allow the master observer to connect to any instance of an Oracle RAC database. The SHOW CONFIGURATION command will show you which databases can be reinstated and which databases must be re-created. Before enabling fast-start failover in data guard broker, the only required precondition is enabling Flashback Database. SET MASTEROBSERVER TO allows you to manually change the observer configuration file. It comes with a GUI and command line interface. Bystanders are part of the Data Guard configuration, but not part of the FSFO configuration. 11.2 rac servicefailover - Note that role changes to logical standby databases always result in physical standby database bystanders being disabled. Any apply delay must be removed before beginning a switchover. SQL>connect /@STAN as sysdba For more details about managing redo transport services using database properties, see Managing Redo Transport Services. The following sections provide more information about the fast-start failover environment: When Fast-Start Failover Is Enabled and the Observer Is Running, Restrictions When Fast-Start Failover is Enabled, Shutting Down the Primary Database When Fast-Start Failover Is Enabled, Performing Manual Role Changes When Fast-Start Failover Is Enabled. Use the EMCLI verb dg_configure_observers. The target standby database is enabled and is in the APPLY-ON state. the observer configuration file is observer.ora. The SRVCTL utility does not automatically take the database role into account, so any time you start a service manually, you must specify the name(s) of the service you want started. fsfo_postcallout are stored in the same location as Thus, the command-line prompt on the observer computer does not Apply services on all other bystander standby databases automatically begin applying redo data received from the new primary database. It doesn't consider how much of that redo has been applied. The word manual is used to contrast this type of failover with a fast-start failover (described in Fast-Start Failover). If the primary database can be mounted, it may be possible to flush any unsent redo data from the primary database to the target standby database using the ALTER SYSTEM FLUSH REDO SQL statement. Do not attempt to reinstate the old primary database if an ORA-752 or ORA-600 [3020] error has occurred at the failover target. Oracle 19c-Performing Dataguard Switchover Using DGMGRL Utility There are two types of failover operations: Graceful or "no-data-loss" failover and Forced or "minimal-data-loss" failover. It is important that all SRVCTL add service options be identical on all the databases so that the services behave the same way before and after a role change. The observer configuration file is a text file and the syntax to define observers and groups is similar to that used in the listener.ora or tnsnames.ora files. The following paragraphs describe the supported availability modes. Attempt to open the primary database, or the following error may be returned: This error may return if the fast-start failover validity check fails or does not complete in under two minutes. This page will not allow you to alter the protection mode. SQL>select sequence#, applied from v$archived_log; 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. Without the credentials, Broker will complete the role transition, but will leave the databases in need of a manual restart. The example assumes that the standby uses the same directory structure as the primary. Create a trigger based on the, Oracle Database PL/SQL Language Reference, Choosing a Target Standby Database for Switchover, Choosing a Target Standby Database for Failover, Scenario 9: Performing a Switchover Operation, Scenario 10: Performing a Manual Failover Operation, Database Service Configuration Requirements, Troubleshooting Problems During a Switchover Operation, How the Broker Performs a Complete Failover Operation, How the Broker Performs an Immediate Failover Operation, Setting the Protection Mode for Your Configuration, Scenario 7: Enabling Fast-Start Failover When a Far Sync Instance Is In Use, Description of "Figure 6-1 Relationship of Primary and Standby Databases and the Observer", Enabling Fast-Start Failover Task 7: Configure Actions Before and After Fast-start Failover (Optional), Directing a Fast-Start Failover From an Application, Fast-start Failover Callout Configuration Files, Oracle Data Guard Command-Line Interface Reference, Description of "Figure 6-2 The Observer in the Fast-Start Failover Environment", Oracle Enterprise Manager Command Line Interface. To run an observer as a background process, use the DGMGRL command START OBSERVER IN BACKGROUND. You want to prevent fast-start failover from occurring because the primary database will resume service soon. Then the STOP OBSERVER command can be issued successfully on the former master observer. This means that in order for a flashback database operation to succeed, observer and the standby both lose contact with the primary. 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. We suggest you try the following to help find what youre looking for: This document will guide you through configuringOracle Data GuardFast-Start Failover (FSFO) using a physical standby database. fast-start failover has not occurred to the target standby database. FSFO builds upon a number of other Oracle technologies and features such as Data Guard, Flashback Database, and Data Guard Broker. client-side broker files, the specified values are used. distance. You can start the observer before or after you enable Select name,open_mode,database_role from v$database; Step:2 Cancel the MRP process If the database is managed by Oracle Clusterware, broker does not open any pluggable stored in the specified path using the default file names. list of the observers that can become the master observer when that 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. Theoretically, this method can be used when a data guard failover occurred between the primary and standby database, but not a switchover. You can upgrade the protection mode later, if necessary, as described in Setting the Protection Mode for Your Configuration. Broker changes database parameters during startup and role transitions via ALTER SYSTEM commands. ASYNC. Oracle Data Guard 11gR2 Administration : Beginner's Guide If a non-zero value is specified for the Problems with automatic reinstatement are frequently due to misconfiguration, so let's look at this in a bit more detail. How to Enable Fast-Start Failover in Oracle Data Guard If both HVR and Data Guard were running without latency or if no changes were made to the source database at the time of the failover, it can be assumed that all databases are synced and the no extra steps are necessary; the steps for Graceful Failover can be followed. This document only talks about switchover involving physical standby database. Dataguard broker is used to automate monitoring and controlling standby setups. change tracking enabled, broker enables block change tracking on the new See Oracle Enterprise Manager Command Line Interface. It is also possible to initiate failover using the dgmgrl failover command. ZERO DATA LOSS: Fast-start failover is enabled with zero data loss. callout configuration scripts fsfo_precallout and The primary and target standby must have connectivity for the STOP OBSERVER command to complete successfully. FastStartFailoverThreshold for reference information about the FastStartFailoverThreshold property. FSFO uses Flashback Database as part of the process of reinstating a failed primary as a standby. return until you issue the STOP OBSERVER command These commands can be issued from the DGMGRL command line, but it is not necessary to log on prior to using them. At this point, you can either: Disable fast-start failover (described in Disabling Fast-Start Failover) and attempt to open the former primary database, Manually reinstate the former primary database, as described in Reenabling Disabled Databases After a Role Change. 8.2 Private Cloud Appliance and . The minimum value is 100 milliseconds. If the DG_ADMIN environment variable is not set, or the A single-instance database must be registered with Oracle Restart in order to publish FAN events via ONS. A switchover guarantees no data loss and is typically done for planned maintenance of the primary system. This exercises the configuration, but triggers failover differently than losing contact with the primary. 3. The example uses the FROM ACTIVE DATABASE clause introduced in 11g that allows RMAN to create a standby database by copying the primary across the network without the need to store the backup files on disk or tape. If the credentials cannot be obtained, then the attempted command fails (but only for the broker configuration whose credentials have not been obtained). Contains the callout configuration file, pre-callout script, If you do not want to use the default, you can define a specific group. The broker initiates a failover after the number of seconds specified by this See Choosing a Target Standby Database for helpful advice. The 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. This support note is available at http://support.oracle.com. guaranteed to lose no data. exit. Maximum availability SYNC or FASTSYNC or ASYNC, Maximum performance SYNC or FASTSYNC or You can use Cloud Control or DGMGRL, to perform either a complete (recommended) or an immediate failover. 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. The command fails if the file does not exist. Oracle also provides Fast Application Notification (FAN) for OCI clients and Fast Connect Failover for JDBC clients. Connect to the target standby database and issue the FAILOVER command to perform a failover, specifying the name of the standby database that you want to become the primary database: Specify the optional IMMEDIATE clause to perform an immediate failover if any of the following conditions are true: An ORA-752 error has occurred at the standby database, An ORA-600 [3020] error has occurred at the standby database and Oracle support has determined that it was caused by a lost write at the primary database. failover configuration file, this script is run. It is also supported for fast-start failover to physical standbys in maximum availability data protection mode. Application Continuity is an Oracle Database feature that enables rapid and nondisruptive replays of requests against the database after a recoverable error that made the database session unavailable. Errors occurring for any other configuration members will not impede the switchover. After the broker receives the STOP OBSERVER request, the request is passed to the observer the next time the observer contacts the broker, and the observer then stops itself. This feature enables RMAN to duplicate an existing database over the network without requiring a backup to disk or tape. Note that if failover was performed on a snapshot standby database, the old primary must be either reinstated or re-created as a physical standby database. Table 6-2 FS_FAILOVER_STATUS Column of the V$DATABASE View. It's a good idea to have at least two hosts configured to run observers so that one can take over if the other fails. Note: this state also occurs on the primary during startup when fast-start failover is possible and neither the target standby database nor the observer are present to confirm it is okay to continue opening the database. Look for the desired data in the RAM. Oracle Data Guard with Fast-Start Failover (FSFO) can provide additional resiliency by setting up the broker on a separate machine. Staff support, hardware and software, security (both software and site), network connections, and bandwidth should be equivalent at both sites. Note the primary and target standby must have connectivity for this command to complete successfully. See theFlashback Database section above for information on storage requirements. This walkthrough assumes that all ORLs and SRLs on the primary and standby databases are the same size. To start an immediate failover, use the DGMGRL FAILOVER TO database-name IMMEDIATE command. The environment is a single instance database without any grid Infrastructure components. The observer does not attempt to reinstate the former primary database. Here's a one-liner observer startup for *nix. The minimum The time interval starts when the observer first loses its connection to the primary database. The default name of the observer runtime data file is The Appendix provides information oncreating a simple wrapper script to start the observer as a background process. value of the FastStartFailoverThreshold property. Create a wallet and set the default username and password to the database's SYSDBA credentials (usually SYS). For example: In the following example, assume the network between the primary database and the observer has failed. Table 6-1 Content of Default Directory for Client-side Files, Contains the observer configuration file that is used by Startup can fail with "ORA-16647: could not start more than one observer" even when no observer is actually running if the previous observer process terminated without deregistering itself and the new observer isn't using the previous fsfo.dat file. See Disabling Fast-Start Failover. You can use the broker's reinstate capability to make a failed primary database a viable standby database for the new primary. The FS_FAILOVER_OBSERVER_PRESENT column, which indicates whether the observer is running and actively pinging the database. specified, the file is stored in an appropriate directory under the broker's the names of the scripts created in the previous step. Switch-over steps: Step-A: Shutdown primary database: SQL> shut immediate; Database closed. Verifies that the target standby database is enabled. Being FSFO ready means that all conditions are met for a successful failover, including having a running observer and sufficient redo transmitted to the failover target to meet durability requirements. Default value is 100 Disabling Fast-Start Failover Using Cloud Control. Credentials Required for Access to Broker Configurations. The observer host is 'observer.demo.org'. SQL> Select Database_role from v$Database; (Note that the target standby cannot be a far-sync instance. Note: the FSFO observer version must match the database version. the SYSDG or SYSDBA privilege. This function can be called from a connection to either the primary or any standby in the configuration. FastStartFailoverLagLimit Determine the number and size of the Online Redo Log files (ORLs). configuration scripts and checks for errors or misconfigurations. When you configure data guard using OCI console, the default mode is set to maxprotection. The observe-only mode for fast-start failover enables you to test how fast-start failover will work in your environment. The broker will not allow a switchover to a standby that has an apply delay configured (DelayMins property is set to a non-zero value). If this occurs, run 'stop observer' and try again. These facilities allow applications written to take advantage of them to receive asynchronous notification of database events, including role transitions. In addition, the database to be reinstated and the new In maximum performance mode, the ability to automatically failover is restored Neither the primary database nor the logical standby database needs to be restarted after the switchover completes. STANDBY>connect /@STAN as sysdba In the event of a For more information, see SET MASTEROBSERVER TO. A far-sync instance cannot be used in maximum protection mode. data (in seconds) specified by the In such cases, the failed primary database is reinstated as a physical standby database. This allows for redundancy in your Data Guard observer setup as well. been enabled on the database prior to the failover and there must be sufficient You can specify particular conditions for which a fast-start failover should occur using either Cloud Control or the DGMGRL ENABLE FAST_START FAILOVER CONDITION and DISABLE FAST_START FAILOVER CONDITION commands. operation: Example 6-1 Fast-start Failover Configuration 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. Standby databases that are disabled during switchover, manual failover, or fast-start failover will not be automatically reinstated. If there is more than one registered observer, then this command returns an error; a name is required if there is more than one observer. After the failover completes, the former primary database is automatically reinstated as a standby database when a connection to it is reestablished, if the FastStartFailoverAutoReinstate configuration property is set to TRUE. Data Guard switchover with dgmgrl - dba-oracle.com 12c upgrade, The below commands will help to bring up standby as primary, https://www.linkedin.com/in/hari-prasath-aa65bb19/, https://www.facebook.com/groups/894402327369506/. It behaves similarly to START OBSERVING and STOP OBSERVING to operate on all the configurations defined in the observer configuration file. For Fast Connection Failover (FCF) to occur, a client must be able to locate the new primary database after a failover. Its primary job is to perform a failover when conditions permit it to do so without violating the data durability constraints set by the DBA. 3. created when the START OBSERVER command is issued. 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. only. You must ensure that the primary database is shut down prior to performing a manual failover. ERROR: Unable to verify the graphical display setup. $DG_ADMIN/config_ConfigurationSimpleName/callout Fast-start failover can incur data-loss within the time specified by FastStartFailoverlagLimit. Valid values are >= 100. Manual failover can be performed even if the pre-condition checks are not met. Set this property for the primary and target standby database if you want the observer to use a different connect identifier than that used to ship redo data (that is, the connect identifier specified by the DGConnectIdentifier property). time specified in the WAIT option. SHOW OBSERVERS [FOR fg_group_name ] shows information about observers for all configurations in the specified group. Setting this property to 'TRUE' (the default) causes the primary to self-terminate. Examine the Broker configuration by logging into dgmgrl on the new primary. When running the START The default value is ALL. As described in theFlashback Database section, Flashback Database takes place in two stages: a restore stage and a media recovery stage. To failover, connect to the standby database and use the DGMGRL FAILOVER TO db-unique-name command. Any unsent redo data residing on the far sync instance is transmitted to the target physical standby prior to converting the physical standby into a primary database. To switchover to a standby that is not the current failover target: John Smiley [jrsmiley@gmail.com] is a persistent storage architect for a major online retailer. To avoid problems due to timing variations, values less than 60 minutes are not recommended and values of 30 or less virtually guarantee Flashback Database failure. the primary database that failed or took longer than the time If it detects that Flashback Database was disabled, either manually, or automatically because Flashback Database discovered a problem, Broker signals "ORA-16827: Flashback Database is disabled". Each group that you define must have at least one broker configuration. The act of switching roles should be a well-planned activity. The FORCE option disables fast-start failover on the database to which you are connected even when errors occur. A switchover is a role reversal between the primary database and one of its standby databases. Synopsis. Note: You can also use TNS aliases defined in the tnsnames.ora file when setting the local_listener parameter. For the RMAN duplicate active database method, the init.ora file (initdb1.ora in the example) requires only one parameter: db_name (it doesn't even have to be the real name of the database - any name will do). Fast-Start Failover allows Data Guard to automatically failover to a previously chosen standby database without requiring manual intervention to invoke the failover. It has two parts in the following order: Configuration declaration this section is mandatory. broker configuration, you must connect through another DGMGRL client Displays only on a logical standby database that has not yet completed loading a copy of the primary database's data dictionary. The Oracle Database 11g observer can make use of specific credentials, allowing the same wallet to be used for multiple observers with different SYS passwords. 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. SQL> Select Database_role from v$Database; Hi, I am working in IT industry with having more than 10 year of experience, worked as an Oracle DBA with a Company and handling different databases like Oracle, SQL Server , DB2 etc On the Oracle Data Guard Overview page in Cloud Control, select the standby database that you want to change to the primary role and click Failover. The following steps all require the database to be in a mounted (not open) state. 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. The current primary database must have its LogXptMode property set accordingly and must have standby redo logs configured. Use the wrapper script to start the observer process when the observer host boots or to restart it if it dies. The "Configuring Authentication" chapter of the Oracle Database Security Guide provides detailed instructions for creating a wallet. The observer is the third party in an otherwise typical primary/standby Data Guard configuration.

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