data guard failover steps

Data guard Configuration details:- Login in to Standby Server:- Step:1 Check the database role and open_mode Select name,open_mode,database_role from v$database; Since a fast-start failover (automatic failover) could become a false failover when the observer or the standby database cannot connect to the primary database within a specific time, which may cost the database to lose some transactions followed by reinstating or recreating the standby database (the former primary database). Event notification and database connection failover support is available to database clients connected to local database services when a broker-managed failover occurs. Verify the standby database instance is mounted. This exercises the configuration, but triggers failover differently than losing contact with the primary. By default the file is named fsfo.dat and is created in the working directory where the observer is started. The role change is directed to the same standby database that was specified for the FastStartFailoverTarget database property on the primary database. There is no need to multiplex SRLs in order to protect redo as with ORLs (the redo is already protected in the ORLs of the primary). Alternatively, if you intend to switch back to the original primary relatively soon, then you may re-enable the disabled standby databases after the switch back. Broker checks to see if Flashback Database is enabled on the primary and failover targets when FSFO is enabled. The default name of the callout configuration file is ORACLE instance shut down. all of the same type (all physical or all logical standby databases), choose the standby The broker preserves the protection mode that was in effect prior to the failover. In the following example, a service named sales is configured to be active in the PHYSICAL_STANDBY role on the primary database NORTH. Then set the configuration protection mode to maximum availability. The following is an example of querying the V$FS_FAILOVER_STATS view: Disabling fast-start failover prevents the observer from initiating a failover to the target standby database. standby database, host, or network failure, etc.). Before stopping an observer, note the following: The observer does not stop immediately when you issue the STOP OBSERVER command. Use synonyms for the keyword you typed, for example, try "application" instead of "software.". Use the SHOW CONFIGURATION BystandersFollowRoleChange command to see the value of this property. The configuration must be operating in either maximum availability mode or maximum performance mode in order to be able to switch over to a logical standby database. A complete failover also attempts to avoid disabling any standby databases that were not the target of the failover, so that they may continue serving as standby databases to the new primary database. After an immediate failover completes, all the standby databases in the configuration, regardless of their type, are disabled. It will not be allowed to open in any event if fast-start failover is enabled. ObserverPingRetry properties before 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. this directory are used to store the files related to the You can find detailed information about all observers, including master observers and backup observers, in the V$FS_FAILOVER_OBSERVERS view. If the protection mode was at maximum availability or maximum performance, it remains unchanged. If the database is managed by Oracle Clusterware, broker does not open any pluggable To disable fast-start failover, use the Fast-Start Failover wizard in Cloud Control or the DGMGRL DISABLE FAST_START FAILOVER [FORCE] command. created when the START OBSERVER command is issued. For Active Oracle Data Guard, it will fail to open up a connection unless its in read-only mode. When you are experiencing network disconnections and you issue the DISABLE FAST_START FAILOVER FORCE command on the primary database or a standby database that does not have connectivity with the primary database, fast-start failover may not be disabled for all databases in the broker configuration. Perform SWITCH LOGFILE if necessary. This can be avoided by first disabling fast-start failover with the FORCE option on the target standby. There can be up to four 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". Use the Cloud Control Fast-Start Failover wizard or the DGMGRL ENABLE FAST_START FAILOVER command to enable fast-start failover. The FastStartFailoverLagLimit configuration property is only used by the broker when enabling fast-start failover for configurations operating in maximum performance mode. stored in the specified path using the default file names. A switchover guarantees no data loss and is typically done for planned maintenance of the primary system. SQL>connect /@STAN as sysdba STANDBY> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY; database (if real-time query is enabled). Bystander standby databases that are not disabled by the broker after the switchover will continue operating in the state they were in before the switchover. If the currently configured mode is maximum protection, Cloud Control will downgrade the mode to maximum availability. Simply use DISABLE FAST_START FAILOVER. A failover may or may not result in data loss depending on the protection mode in effect at the time of the failover. Standby databases that are disabled during switchover, manual failover, or fast-start failover will not be automatically reinstated. The previous examples dealt with setting up only one service on a database. Oracle Data Guard work on two database roles Primary and Standby. When the primary database and the (non-target) standby database regain network connectivity, the broker will propagate its current fast-start failover setting (ENABLED or DISABLED) to the non-target standby. Post failover, there are two methods of rebuilding your failed primary Method 1: Rebuild from scratch -> RMAN duplicate Method 2: Flashback database -> only if Flashback was enabled Reinstate failed primary: When you use data guard broker, with just one command, the primary can be rebuilt. Fast-start failover can be used only in a broker configuration and can be configured only through DGMGRL or Cloud Control. The foundation of FSFO is Data Guard - a primary and at least one standby. In a Data Guard environment primary database is open in read write mode and the standby database in read only mode for reporting purpose. 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. STAN is now transitioned to the primary database role.Now your PHYSICAL STANDBY Database has become PRIMARY. Open another prompt and connect to SQLPLUS: Figure 6-2 The Observer in the Fast-Start Failover Environment. https://www.facebook.com/dbahariprasath/? 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. Just be sure to include a Flashback Database history check in the script to provide an option to abort if a failover would require a manual reinstate. Duplicate configuration names in configuration definitions are not allowed. In addition, a logical standby database may contain only a subset of the data present in the primary database. If only a file name is SWITCHOVER command, and the databases are managed by Oracle directory does not have the required permissions, broker does the following: When you run DGMGRL commands, if a path and file name are explicitly specified for Whether you reinstate or re-create a database depends on whether you performed a switchover or failover, on the type of standby database that was the target of the operation, and on whether or not there are sufficient flashback logs. Observers should be installed and run on a computer system that is separate from the primary and standby systems. The service is then configured to be active in the PRIMARY role on the standby database SOUTH, so that it will be active on that database after a role transition. 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. (If there are other conditions, unique to an application, that would warrant a fast-start failover then the application can be set up to call the DBMS_DG.INITIATE_FS_FAILOVER function and start a fast-start failover immediately should any of those conditions occur. Applications can initiate FSFO failover directly using the DBMS_DG.INITIATE_FS_FAILOVER procedure with an optional message text that will be displayed in the observer log and the primary's alert log. enabling fast-start failover. In such cases, the failed primary database is reinstated as a physical standby database. Displays when the target standby database does not have all of the primary database redo data and the configuration is operating in maximum availability mode. This database property is used to specify how the observer should connect to and monitor the primary and standby database. Any database that was disabled while multiple role changes were performed cannot be reinstated. You cannot perform a switchover to a snapshot standby database unless you first convert it back to a physical standby database. The FastStartFailoverThreshold time interval starts when the observer first detects there might be a failure with the primary database. The minimum detection time is 6 seconds, which is the default Oracle Real Application Clusters Administration and Deployment Guide for more information about configuring FAN, FCF, and ONS on an Oracle Real Application Clusters (Oracle RAC) database. In addition, the database to be reinstated and the new Failing over the database won't do much good if applications and other database clients don't know where the primary went. Enable Active Data Guard for read-only workloads. For a system to process an instruction involving data access, these are the certain steps involved: Fetch the block of data from the hard disk (secondary/permanent storage) to the primary memory (e.g. Dataguard Switchover Using DGMGRL A switchover is a role reversal between the primary database and one of its standby databases. In maximum protection mode, an automatic failover is always possible because the The failover time is dependent upon whether the target standby database (physical or logical standby database) has applied all of the redo data it has received from the primary database. This file contains connect identifiers to both the primary and the target standby databases. 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. 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. SQL Apply on all other bystander standby databases automatically begin applying redo data received from the new primary database. Configure Data Guard Broker to manage and monitor the Data Guard configuration. To maintain a viable disaster-recovery solution in the event of another disaster, you may need to perform additional steps. Learn how your comment data is processed. This is cleared on both when the reinstatement has been completed. Starting the Observer Using Cloud Control. cannot use a different name for this file. 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. During an immediate failover, the broker performs the failover steps described in How the Broker Performs an Immediate Failover Operation. 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.

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