PRIM>connect /@PRIM as sysdba 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. 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. Add an entry to the oratab file for the standby, db1:/u01/app/oracle/product/11.1.0/db_1:Y. on ob3-host and ob4-host will not After the fast-start failover completes successfully, the master observer will attempt to reinstate the former primary database as a new standby database when a connection to the former primary database is reestablished, and the FastStartFailoverAutoReinstate configuration property is set to TRUE. cannot use a different name for this file. If the designated fast-start failover target develops a problem and cannot be the target of a failover, then the broker automatically changes the fast-start failover target to one of the other candidate targets. For example: Scenario 6: Enabling Fast-Start Failover and Starting the Observer. Make sure the last redo data transmitted from the Primary database was applied on the standby database. If the primary database has multiple standby databases, then you can specify multiple fast-start failover targets, using the FastStartFailoverTarget property. milliseconds and that of ObserverRetryCount is 10. The standby VM (myVM2) has the Oracle software installed only. directory has the same permissions as its parent directory. Whether or not you need the FORCE option depends mostly on if the primary and target standby database have network connectivity: If the primary and target standby database have network connectivity, and the database to which you are connected has network connectivity with the primary database, the FORCE option has no effect. 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. These commands can be issued from the DGMGRL command line, but it is not necessary to log on prior to using them. 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. Use the FastStartFailoverTarget configuration property on the current primary database to specify one or more fast-start failover targets. Oracle Database Reference for more information about the V$FS_FAILOVER_OBSERVERS view. to set the time taken to detect a failure on the primary database: Set the FastStartFailoverThreshold command on the observer computer: The observer is a continuously executing process that is This means that in order for a flashback database operation to succeed, observer and the standby both lose contact with the primary. If the credentials cannot be obtained, then the attempted command fails (but only for the broker configuration whose credentials have not been obtained). The new ConfigurationWideServiceName configuration property can be used to simplify setting up this connect identifier. the current working directory. Standby databases not involved in the switchover (known as bystander standby databases) continue operating in the state they were in before the switchover occurred and will automatically begin applying redo data received from the new primary database. If the primary or target standby databases lose connections to all backup observers, then the broker does not try to nominate a backup observer as the new master observer, and the broker reports that the configuration is not observed. The observer automatically starts the reinstatement process. Note that the value of the FastStartFailoverPmyShutdown configuration property must be FALSE for the primary to stall indefinitely under these conditions. To see Manual Switch Over Manual SwitchOver in Oracle To see Manual Fail Over Manual Failover in Data Guard With Oracle Data Guard [] In disaster situations where a failover is necessary, you may be more limited as to which standby database is the best one to pick up the failed primary database's activities. ob2-host can be a master observer when After step 3 completes, you can open the new Primary database STAN: It behaves similarly to START OBSERVING and STOP OBSERVING to operate on all the configurations defined in the observer configuration file. However, you can change the name or the location of the file if you start the observer using the DGMGRL START OBSERVER command and include the FILE IS qualifier. Commands For Managing Observers on Multiple Configurations. Issue the following SRVCTL commands: Now the correct services are running on the correct databases. This configuration property establishes an acceptable limit, in seconds, that the standby is allowed to fall behind the primary in terms of redo applied, beyond which a fast-start failover will not be allowed. Reinstatement is supported only after failover in a broker configuration. on particular instances based on the service configuration. It doesn't consider how much of that redo has been applied. Disabling Fast-Start Failover Using Cloud Control. If there are multiple observers, then only one of them is the master observer. Fast-start failover can incur data-loss within the time specified by FastStartFailoverlagLimit. Manual Failover in Data Guard - ORACLE-HELP In order to fully automate switchover, Broker needs SYSDBA credentials in order to restart one or both databases. For this build, we will use a single physical standby database. Use the SQL ALTER DATABASE MOVE DATAFILE command to rename or relocate an online data file on a physical standby that is a fast-start failover target if the standby is mounted, but not open. 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. the current working directory, Uses standard output for displaying the observer logs. This walkthrough uses Maximum Availability mode to achieve "zero data loss". You can start, stop, and show observers for a group of configurations. learning with R and Python are also covered in this step-by-step tutorial. This section describes how to configure and verify each prerequisite. The database cannot provide fast-start failover status information. As a result the observer may still initiate fast-start failover to the target standby database, if conditions warrant a failover. Additionally, the new master observer is identified in the output shown for the SHOW FAST_START FAILOVER and SHOW OBSERVER commands. There can be up to four observers for a single Data Guard configuration. fast-start failover to the target standby database if conditions warrant a failover. The following conditions apply when multiple observers are registered for one configuration: When fast-start failover is enabled, one of the observers is the master observer. In this case, the observer cannot perform a fast-start failover even if conditions warrant a failover. They rely on Oracle Data Guard for high availability databases, with a standby database running in a different availability zone. Switchover Steps. This exercises the configuration, but triggers failover differently than losing contact with the primary. receives redo data from a far sync instance. Bounce your database and verify database name its open mode and its role: SQL> shutdown immediate; ORA-01109: database not open Database dismounted. This function can be called from a connection to either the primary or any standby in the configuration. 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. under the $DG_ADMIN directory. The Appendix provides information oncreating a simple wrapper script to start the observer as a background process. become the master observer. The target standby database has contact with the primary database. Which three are prerequisites for enabling fast-start failover? A far-sync instance cannot be used in maximum protection mode. drain_timeout amongst the active services. If failover is not possible for some reason, then the master observer will continue checking whether the standby database is ready to fail over. SQL> startup ORACLE instance started. For example, if all your physical standbys are also unavailable, then failing over to a logical standby is your only choice. Step:5Bounce your database and verify database name its open mode and its role. They may be reinstated if Flashback Database is enabled on those databases. Multiplexing SRLs merely adds unnecessary IO and can increase commit latency. You want to prevent fast-start failover from occurring because the primary database will resume service soon. Synopsis. failover configuration file, this script is run. 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. RMAN also copies the spfile and password files and you can change the values for individual parameters. FS_FAILOVER_OBSERVER_HOST shows the name of the computer on which the master observer is running, FS_FAILOVER_OBSERVER_PRESENT shows whether or not the master observer is connected to the local database. When this command is issued, the actual alter database recover managed standby database cancel; Step:3 The below commands will help to bring up standby as primary. (See Disabling Fast-Start Failover for important considerations when using the FORCE option.). This page will not allow you to alter the protection mode. To start a switchover using Cloud Control, select the standby database that you want to change to the primary role and click Switchover. Create a wallet and set the default username and password to the database's SYSDBA credentials (usually SYS). If you do not want to use the default, you can define a specific group. The standby database must be re-created or reinstated before it can serve as a standby for the new primary database. This section lists the steps the master observer takes to determine if a fast-start failover is needed and then to perform one, if necessary. In the following example, ObserverReconnect is set to 30 seconds. See Installing and Starting the Observer. 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. STOP OBSERVING, and SET See theFlashback Database section above for information on storage requirements. JAVA applications can use FAN programmatically by using the JDBC FAN application programming interface to subscribe to FAN events and to execute event handling actions upon the receipt of an event. If you will be using RMAN to create the standby database, it also needs a static service to restart the database being created. As shown in the table, fast-start failover can be enabled in maximum availability The selected standby database that will be the fast-start failover target must receive redo directly from the primary database. When enabled, re-create the standby database. Bystanders are part of the Data Guard configuration, but not part of the FSFO configuration. In order to accommodate all load conditions, Oracle recommends having at least one more SRL group than the number of ORL groups of the same size. This can be avoided by first disabling fast-start failover with the FORCE option on the target standby. One is the master It uses the connect identifier specified in the observer configuration file to locate the credentials for a broker configuration from the Oracle wallet. If you already have an FRA, you may need to increase its size in order to accommodate the Flashback Database files. Refer to the appropriate Oracle RAC or Oracle Restart documentation for further information. See the Oracle Maximum Availability Architecture technical briefs at: When setting the FastStartFailoverLagLimit configuration property, consider these tradeoffs between performance and potential data-loss: A low lag limit will minimize data loss but may impact the performance of the primary database. observer as a foreground process. DGMGRL to manage multiple observers on multiple configurations. For example: The default value for the FastStartFailoverThreshold property is 30 seconds and the lowest possible value is 6 seconds. This method will disable fast-start failover on all databases in the broker configuration. Performing Database Failover with Oracle 11g Data Guard If you like a connect-time failover to survive across a data guard switchover, you need another way to do it. The connect descriptor can be configured in one of two ways: Oracle Database PL/SQL Language Reference for more information about the DB_ROLE_CHANGE system event. 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. ConfigurationSimpleName represents alter system set standby_file_management=auto; This parameter must be set before the primary can be opened in Maximum Availability mode. 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. (Yes, bystanders need Flashback Database too). You cannot create the standby DB system in a different AD from the primary DB system. configuration. The values that indicate FSFO is ready for failover are listed below. Install the DGMGRL command-line interface on the observer computer as described in Oracle Data Guard Installation. If the database is not managed by Oracle Clusterware, 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. enabling fast-start failover. Note: If you have just enabled archivelog mode, force an archive log creation ( alter system archive log current) to ensure that at least one archive log exists. Thus, the validity of the values of these properties is not verified until after the switchover. 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 minimum value of ObserverPingInterval is 100 By default, the observer uses the same connect identifiers used by Data Guard for redo transfer and information exchange between the primary and standby ( DGConnectIdentifier in Oracle Database 11g, InitialConnectIdentifier in Oracle Database 10g). SQL> Select Database_role from v$Database; Set the FastStartFailoverThreshold property to specify the number of seconds you want the observer and target standby database to wait (after detecting the primary database is unavailable) before initiating a failover. [PATCH v5 0/6] Add Toshiba Visconti Video Input Interface driver We'll start with switchovers. Use the wrapper script to start the observer process when the observer host boots or to restart it if it dies. The foundation of FSFO is Data Guard - a primary and at least one standby. Oracle 11g Manual Data Guard Part-II - DBAtricksWorld.com The total storage requirement is proportional to the number of distinct blocks changed during snapshots - e.g. Ideally the primary, standby, and observer will be in geographically separate areas. In addition to setting the configuration protection mode to maximum performance, you will also need to ensure that the LogXptMode database property for both the primary and target standby database is set to ASYNC. Staff support, hardware and software, security (both software and site), network connections, and bandwidth should be equivalent at both sites. This is particularly useful when registering with multiple listeners where the parameter value would otherwise exceed the 255 character limit. MASTEROBSERHOST TO command. present, you must start the observer manually using the following You can also reinstate bystander standby databases that were disabled during a failover operation. This is the recommended method for disabling fast-start failover. This is cleared on both when the reinstatement has been completed. 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. How to reinstate the old Primary as a Standby after Failover in #Oracle Change Standby to Primary Database. value of the FastStartFailoverThreshold property. Automatic failover is optional and can be enabled or disabled on your Autonomous Container Databases with Autonomous Data Guard. Commit latency is not affected by redo transfer, but committed transactions whose redo has not been received by the standby will be lost during failover. Do this prior to every failover test. This feature enables RMAN to duplicate an existing database over the network without requiring a backup to disk or tape. This can be done regardless of whether the failover was done to a physical, logical, or snapshot standby database. Data Guard switchover with dgmgrl - dba-oracle.com SHOW OBSERVER command to confirm that the switch took place. Table 6-3 FS_FAILOVER_OBSERVER_PRESENT Column of the V$DATABASE View, The master observer is currently connected to the local database, The master observer is not connected to the local database. fast-start failover succeeds, if a post-callout script is specified in the fast-start 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. In this example, the original primary data is called PRIM and the original standby database is called STAN. SQL>ALTER SYSTEM SWITCH LOGFILE; switch does not happen until the next time the primary contacts the target standby, This brings up the General Properties page that provides a Reinstate button. The steps in this section describe the tasks involved to perform a manual failover. specified, the file is stored in an appropriate directory under the broker's Administration at the target standby site should be as comprehensive as that at the primary site because the standby database may assume the primary role without prior notice. (For example, if the DBMS_LOGSTDBY.SKIP procedure was used to specify which database operations done on the primary database will not be applied to the logical standby database.). How to Test Data Guard Fast-Start Failover by Shutting Down Primary 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. Each group that you define must have at least one broker configuration. 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. operation. How To Setup Dataguard Broker Configuration (DG Broker) In 19c This guide uses the naming convention of appending an underscore followed by a letter to the db_name to create the db_unique_name. Database dismounted. The playground: Logical standby databases that are disabled during failover can be reinstated. Issue the following commands on Primary database and Standby database to find out: Do not attempt to reinstate the old primary database if an ORA-752 or ORA-600 [3020] error has occurred at the failover target. Verify the target standby database is ready for failover. In an immediate failover, it is also possible to failover to a standby database (terminal standby) that gets redo from another standby database (cascader). 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". If clients are already configured to automatically time out and reconnect if they don't get a response from the database, a simple but effective approach is to use a network alias (e.g.