Performing Database Failover with Oracle 11g Data Guard Remember to check Flashback Database history before aborting the primary. This property cannot be used to prevent the primary database from shutting down if a fast-start failover occurred because a user configuration condition was detected or was requested by an application by calling the DBMS_DG.INITIATE_FS_FAILOVER function. 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. failure on the primary database. It's generally a good idea to store the state file in a directory associated with the database to avoid locking issues when running multiple observers on the same host. Media Recovery - Once the restore is complete, recovery proceeds as a typical media recovery, applying redo from archived and online redologs and rolling back uncommitted changes with undo. Switch-over steps: Step-A: Shutdown primary database: SQL> shut immediate; Database closed. However, re-enabling Flashback Database will require a bounce since the database must be mounted and not open. to set the time taken to detect a failure on the primary database: Set the FastStartFailoverThreshold When this property is set to the default value of 0, it prevents the observer from periodically establishing a new connection with the primary database. If automatic reinstatement fails, the broker will log errors and the former primary database will remain in the mounted state. The command SHOW OBSERVER provides detailed information about registered observers. FSFO is a feature of Broker which records information about the failover target, how long to wait after a failure before triggering a failover, and other FSFO specific properties. Therefore, the target standby never falls behind the primary If possible, confirm that fast-start failover has not Configure Data Guard Broker to manage and monitor the Data Guard configuration. There are two types of failover operations: Graceful or "no-data-loss" failover and Forced or "minimal-data-loss" failover. configuration property. The observer persistently maintains information about the fast-start failover configuration in a binary file created in the working directory where you started the observer. The default name of the observer runtime data file is Dataguard Switchover Using DGMGRL A switchover is a role reversal between the primary database and one of its standby databases. data (in seconds) specified by the When you start a switchover, the broker verifies that at least one standby database, including the primary database that is about to be transitioned to the standby role, is configured to support the overall protection mode (maximum protection, maximum availability, or maximum performance) after the switchover is completed. Note that the value of the FastStartFailoverPmyShutdown configuration property must be FALSE for the primary to stall indefinitely under these conditions. 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. pre-callout configuration script and post-callout configuration script. This prevents a "split brain" condition if a failover occurs since none of the changes made to the isolated primary can be made permanent. an alias of the broker configuration name. A far sync instance or Zero Data Loss Recovery Appliance is not a database and therefore cannot be the target of a role transition. Note: if the observer loses contact with the primary, but the standby does not, the observer can determine that the primary is still up via the standby. commands. Before stopping an observer, note the following: The observer does not stop immediately when you issue the STOP OBSERVER command. A complete failover can occur without any data loss, depending on the destination attributes of redo transport services, but an immediate failover usually results in some data loss. There is no impact on your current configuration or on applications. Dataguard switchover and failover steps in Oracle If the credentials cannot be obtained, then the attempted command fails (but only for the broker configuration whose credentials have not been obtained). Use the FastStartFailoverTarget configuration property on the current primary database to specify one or more fast-start failover targets. observer, whether it is currently connected to the primary and target standby databases, using the same SYS credentials you used when you connected to the Therefore, the detection time can be reduced to nearly Stopping the Observer When There is Only One Observer. If fast-start failover is disabled, then manual failover may still be possible. 3. When using DGMGRL, you need to issue the SWITCHOVER command, specifying the name of the standby database that you want to change into the primary role. See Oracle Enterprise Manager Command Line Interface. 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. To stop it, you can do either of the following: Choose the Stop Observer option on the first page of the fast-start failover wizard and click Continue at the bottom of the page. If the PreferredObserverHosts property is set for the current ASYNC. Suppose you have a primary database, BOSTON, and a standby database, CHICAGO. There are configuration requirements that must be met in order to publish and properly handle FAN events generated as the result of a broker-managed failover. Verify the target standby database is ready for failover. If the agent is not If the standby database is not enabled for management by the broker, then the failover cannot occur. Thus, the validity of the values of these properties is not verified until after the switchover. Enable Fast-Start Failover Using Cloud Control. Figure 6-2 The Observer in the Fast-Start Failover Environment. The FastStartFailoverThreshold time interval starts when the observer first detects there might be a failure with the primary database. It will also alert you to databases that have had Flashback Database disabled at some point after FSFO was enabled. 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. To run an observer as a background process, use the DGMGRL command START OBSERVER IN BACKGROUND. After a switchover completes, the broker preserves the overall Oracle Data Guard protection mode as part of the switchover process by keeping the protection mode at the same protection level (maximum protection, maximum availability, or maximum performance) it was at before the switchover. 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 manually stop a specific observer or all observers. When running the START If you have not used the SET ObserverConfigFile command after starting the current DGMGRL client, then the result will always be: ObserverConfigFile=observer.ora. We'll start it interactively for now to verify that everything's working. 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. must ping the primary database. 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 The remaining Data Guard-related parameters will be set by Broker later in the walkthrough. become the master observer. However the target can receive redo from a far sync instance.). The minimum value of ObserverPingInterval is 100 Automatic failover is optional and can be enabled or disabled on your Autonomous Container Databases with Autonomous Data Guard. SQL> startup ORACLE instance started. Reinstatement will have to be accomplished by other means (manual or scripted Broker commands). If the standby database's redo applied point is within that many seconds of the primary database's redo generation point, a fast-start failover will be allowed. Broker is a Data Guard management utility that maintains state information about a primary and its standby databases. 1. *PATCH v5 0/6] Add Toshiba Visconti Video Input Interface driver @ 2023-01-11 2:24 Yuji Ishikawa 2023-01-11 2:24 ` [PATCH v5 1/6] dt-bindings: media: platform: visconti: Add Toshiba Visconti Video Input Interface bindings Yuji Ishikawa ` (5 more replies) 0 siblings, 6 replies; 42+ messages in thread From: Yuji Ishikawa @ 2023-01-11 . restart the new physical standby database. The target standby database has contact with the primary database. stored in the specified path using the default file names. When enabled, re-create the standby database. How To Configure Client Failover For Data Guard Connections - Oracle The following is an example of starting an observer as a background process: The START OBSERVER IN BACKGROUND command uses Oracle wallet to obtain credentials to log into the database server and register observers. Errors occurring for any other configuration members will not impede the switchover. The examples shown in this section do not necessarily show the specific attributes you might need to use in your own environment. Oracle 19c-Performing Dataguard Switchover Using DGMGRL Utility 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. Before a The only exception to this is failovers to snapshot standby databases. This is true regardless of the settings for the FastStartFailoverPmyShutdown and FastStartFailoverAutoReinstate configuration properties. The primary database can be opened even if there is no acknowledgement from the observer or target standby. callout directory. 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. The broker allows the failover to proceed as long as there are no errors for the standby database that you selected to participate in the failover. Learn how to use Oracle Data Guard broker to manage databases during switchover and failover. When fast-start failover is enabled, the primary and standby randomly choose one of the registered observers to be the master. Then, on the Fast-Start Failover Change Mode page, click Enabled. If these parameters are modified outside of Broker, it raises a warning. Use the oraenv script provided by Oracle. specified, the file is stored in an appropriate directory under the broker's 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. Tasks that must be performed before and after a fast-start failover Change Standby to Primary Database. Then set the configuration protection mode to maximum availability. Nothing will ruin your day faster than finding out that the standby the observer just failed over to is 12 hours behind in applying redo. Verify the primary database instance is open. See Disabling Fast-Start Failover. created when the START OBSERVER command is issued. After a complete failover finishes, any bystander standby database that is not viable as a standby for the new primary database will be disabled by the broker. Data Guard Broker Failover - DBA Genesis Support See the START OBSERVER You can create two callout configuration scripts, a Fast-Start Failover in Oracle 11g Data Guard - Database Journal instructions for the DGMGRL command-line interface. 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. 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. On primary database NORTH, execute the following: On standby database SOUTH, execute the following: Services that are to be active while the database is in the physical standby role must also be created and started on the current primary database regardless of whether the service will be started on that database or not. It will not be allowed to open in any event if fast-start failover is enabled. environment variable is set and the specified directory has the Both Cloud Control and the DGMGRL CLI will do this automatically as part of failover. 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. We will create 4 SRLs starting with group# 11. In this case, only observers on ob1-host and Expected output is shown in blue text. 3. Automatic failover quickly and reliably fails over the standby Autonomous database to the primary database role, without requiring you to perform any manual steps. irrespective of its content, indicates that the script executed successfully. Physical Standby Database SWITCHOVER & FAILOVER Operations 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. The redo transport mode used to send redo to the target standby database or the database currently in the primary role. 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. ObserverPingRetry configuration properties. 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 This method will disable fast-start failover on all databases in the broker configuration. To optimize the log apply rate: Do not configure the DelayMins database property to delay applying archived redo log files to the standby database (see Managing Log Apply Services for more information). If this occurs, run 'stop observer' and try again. An spfile is required to persist these changes. The ObserverOverride configuration property, when set to TRUE, allows an automatic failover to occur when the observer has lost connectivity to the primary, even if the standby has a healthy connection to the primary. Displays on the primary database after loss of connectivity to the target standby database and the change to the UNSYNCHRONIZED state (maximum availability mode) or to the TARGET OVER LAG LIMIT state (maximum performance mode) cannot be confirmed by either the target standby database or the observer. A trigger on the DB_ROLE_CHANGE system event can be used to update the naming service and, with the proper client cache TTL settings, clients can connect to the new primary very quickly. A failed ping is a ping to Then, 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. fast-start failover operation, the observer checks if a fast-start failover See Oracle Data Guard Concepts and Administration for more information on using the ALTER SYSTEM FLUSH REDO statement. Ensure this file cannot be read by unauthorized users. under the $DG_ADMIN directory. In addition, the database to be reinstated and the new Database dismounted. groups used by multiple configuration commands. You might, for instance, use this to allow the observer to monitor the databases using the same connect identifiers as the client applications. In maximum protection mode, set the LogXptMode database property to SYNC (note that in maximum protection mode, a far sync instance cannot be used to ship redo to a standby). $DG_ADMIN directory. command for more information about starting the ensure that it has the required permissions. Be aware that if you issue the following manual commands on either of those databases, then both the SALESRO and SALESRW services would be started on the databases regardless of what you may have earlier specified with the SRVCTL -role qualifier. Reinstatement of the failed primary database as a new standby database failed. By choosing the standby database with the least amount of unapplied redo, you can minimize the overall time it takes to complete the switchover operation. Immediately after issuing command in step 2, shut down and restart the standby instance STAN: A switchover is a role reversal between the primary database and one of its standby databases. If the DG_ADMIN environment variable is not defined, or the 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. Enabling fast-start failover and starting an observer process involves the following tasks. Prepare the primary database in advance for its possible future role as a standby database in the context of the overall protection mode (see Managing Data Protection Modes). /home1/dataguard/config_NorthSales/callout/fsfocallout.ora. Note that the new primary database does not need to be restarted. Set both these properties to achieve a primary failure detection time of 1 What is true about Data Guard setup with fast-start failover? The command fails if the file does not exist. Add the primary database and each standby database to the address list. We can always fail over to it or have it happen automatically if for some reason the primary Managed Instance has [] All database connections associated with the observer, including the initial connection, must use dedicated server connections. The word manual is used to contrast this type of failover with a fast-start failover (described in Fast-Start Failover). Use the EMCLI verb dg_configure_observers. A switchover guarantees no data loss and is typically done for planned maintenance of the primary system. These clients can be configured for Fast Connection Failover (FCF) to automatically connect to a new primary database after a failover. primary. Using Shared Server (MTS) or connection pooling can result in unpredictable behavior. Specifying Preferred Observers Based on Current Primary. 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. To allow the master observer to automatically reinstate the former primary database, the database must be started and mounted. You cannot create the standby DB system in a different AD from the primary DB system.