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. Observer sites monitor the fast-start failover environment. maximum availability and maximum performance modes, to avoid a If the group name is not provided, then a new observer is started for each broker configuration defined in observer.ora. Before enabling fast-start failover in data guard broker, the only required precondition is enabling Flashback Database. fsfocallout.ora and they have the required permissions. 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. You can also switch the master observer hosts for a group of configurations to one specific host. Note that the broker does not use the properties to set up redo transport services and Redo Apply services until you actually switch over the primary database to the standby role. Use the EMCLI verb dg_configure_observers. RAM). However, no additional data is applied on the standby database once you invoke the failover. 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. These are the actions the broker performs after you start a switchover. The following example displays the contents of the fast-start failover PRIM>SHUTDOWN IMMEDIATE; 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. If errors occur during the disable operation, the broker returns an error message and stops the disable operation. The primary database, it attempts to disable fast-start failover on as many databases in the configuration with which it has a network connection. What is true about data guard set up with fast-start failover (FSFO) in Oracle Cloud Infrastructure (OCI)? For Active Oracle Data Guard, it will fail to open up a connection unless its in read-only mode. Logical standby databases that are disabled during failover can be reinstated. the observer on ob2-host to become the master Instead, when broker notifies the Oracle connectivity with target standby. Switch-over steps: Step-A: Shutdown primary database: SQL> shut immediate; Database closed. callout configuration scripts fsfo_precallout and 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. We want the observer to be able to automatically reinstate the former primary as a standby after our failover tests, so before each test, make sure that Flashback Database has at least 30 minutes of history. You can manually stop a specific observer or all observers. To see Manual Switch Over Manual SwitchOver in Oracle To see Manual Fail Over Manual Failover in Data Guard With Oracle Data Guard [] The NetTimeout property specifies the number of seconds LGWR will block waiting for acknowledgment from the standby in synchronous mode before considering the connection lost (corresponds to the NET_TIMEOUT option of log_archive_dest_n). performance protection mode with fast-start failover. Create a unique connect alias for each database. Configure one or more active standby databases Minimize downtime for upgrades In a Managed Instance with multiple databases in Azure we can have high availability. 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. 2. Choosing a Target Standby Database for Switchover and Choosing a Target Standby Database for Failover provide guidelines to help you choose a target standby database. failover with the FORCE option on the primary database. switch does not happen until the next time the primary contacts the target standby, See FastStartFailoverTarget for more information about this property. This file contains connect identifiers to both the primary and the target standby databases. The target standby database has contact with the primary database. The following example shows you how to set up more than one service on a database and how using the broker ensures that the correct service starts on the correct database. November 20, 2009. If fast-start failover is disabled, then manual failover may still be possible. Flashing back a database is much faster and more seamless (one simple DDL statement) than traditional point-in-time or SCN-based recovery. If there are multiple observers, then only one of them is the master observer. It can be useful to perform such queries because fast-start failovers are fully automated and can occur at any time. Perform SWITCH LOGFILE if necessary. To do this, use the SET ObserverConfigFile and SHOW ObserverConfigFile commands. Controlfile is permanently damaged because of a disk failure. Subsequent changes to the same block during the same snapshot are not recorded. Using Cloud Control, you can view the value of the ApplyLag column for each standby database in the Standby Databases section of the Oracle Data Guard Overview page. Verifies that the primary and the target standby databases are in the following states: The primary database is enabled and is in the TRANSPORT-ON state. property. Writing the wrapper itself and the means to determine when to execute it are up to you. In such a case, no attempt is made to transmit any unsent redo from the cascader to the terminal standby. FastStartFailoverLagLimit You can start, stop, and show observers for a group of configurations. The subcommands for this verb include start, stop, setMaster, show, and delete_alternate_observer. We'll leave the other properties at their default values for the walkthrough, but you should become familiar with all of the Broker config and database properties. The guide attempts to be operating system agnostic; however, some examples may contain platform specific elements such as path and file naming conventions. The behavior of the broker if the master observer fails depends on whether the broker configuration has one observer or multiple observers. It could optionally also be removed from the primary database if there is no intention to ever run this service on the current primary database. The group of broker configurations to be managed is declared in the observer configuration file. If the Cloud Control agent is installed on the observer 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. For reliable startup, the initial connection should always be made to the primary. If fast-start failover is If the target is a snapshot standby database, the broker first converts the database back to a physical standby and then starts Redo Apply to apply all the accumulated redo before completing the failover and opening the database as a primary database. This is the recommended method for disabling fast-start failover. The physical and snapshot standby databases will have to be re-created from a copy of the new primary database. Failover:- 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. To start an immediate failover, use the DGMGRL FAILOVER TO database-name IMMEDIATE command. Conditions shown in blue are enabled by default. A far-sync instance cannot be used in maximum protection mode. enabling fast-start failover. After step 3 completes, you can open the new Primary database STAN: Enabling Fast-Start Failover describes how to start observers as a part of the step-by-step process to enable fast-start failover. Note: Many of the Broker database properties correspond to database spfile parameters. 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. return until you issue the STOP OBSERVER command Therefore, the detection time can be reduced to nearly It may be possible to convert the old Primary into a Standby database now instead of having to do a time consuming duplicate again. When fast-start failover is enabled, the broker determines if a failover is necessary and initiates the failover to the current target standby database automatically, with no need for manual intervention. In order to apply redo data to the standby database as soon as it is received, use Real-time apply. To start a switchover using Cloud Control, select the standby database that you want to change to the primary role and click Switchover. [PATCH V3 0/6] ASoC: codecs: Add Awinic AW883XX audio amplifier driver configuration property. 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 see the specific parameter, use the "show database StatusReport" command. Starting with Oracle Database Release 21c, use the DG_ADMIN A switchover guarantees no data loss. The reinstated database acts as the fast-start failover target for the new primary database, making a subsequent fast-start failover possible. Ensure that the required permissions are granted to the DG_ADMIN 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. 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. Dataguard Configuration details:- Login in to Standby Server:- Step:1 Check the database role and open_mode Select name,open_mode,database_role from v$database; Step:2 Cancel the MRP process alter database recover managed standby database cancel; Step:3 The below commands will help to bring up standby as primary Restart the database to the mounted state, Use Cloud Control or DGMGRL to reinstate the database. lower detection times for primary database failures, you must A value of TRUE helps to ensure that an isolated primary database cannot satisfy user queries. Broker will validate the configuration, set parameters on both databases, and start managed recovery. Simply use DISABLE FAST_START FAILOVER. Oracle Data Guard Manual Failover - ORACLEAGENT BLOG Provides an automatic failover environment This function can be called from a connection to either the primary or any standby in the configuration. If a fast-start failover was initiated because the primary database had crashed or lost connectivity with the master observer and target standby database, then the master observer automatically attempts to reinstate the former primary database as a standby database, if the FastStartFailoverAutoReinstate configuration property is set to TRUE. to set the time taken to detect a failure on the primary database: Set the FastStartFailoverThreshold A switch-over allows the primary database to switch roles with its standby database. Enable Active Data Guard for read-only workloads. To verify the readiness of the fast-start failover configuration, issue the DGMGRL SHOW CONFIGURATION VERBOSE command or the SHOW FAST_START FAILOVER command on the primary database. To stop the observer, see Stopping the Observer. Steps for FAILOVER the Dataguard environment DG_BROKER_START is set to TRUE and DG_BROKER_CONFIG_FILEn are set correctly SQL> sho parameter broker For each observer, the V$FS_FAILOVER_OBSERVERS view provides the See "Database Service Configuration Requirements" for additional information about how the broker interacts with Oracle Restart. If the FastStartFailoverPmyShutdown configuration property is set to TRUE, then the former primary database will have been automatically shut down and must be manually restarted before the master observer can attempt to reinstate it. Depending on the failover and the types of standby databases involved, some of the databases may need to be reinstated or re-created. Fast-start failover can incur data-loss within the time specified by FastStartFailoverlagLimit. 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. The master observer cannot connect to the target standby database, What Happens if the Observer Fails? All database connections associated with the observer, including the initial connection, must use dedicated server connections. It shuts down or stalls because it is likely a failover has occurred. Whereas a switchover to a logical standby database will invalidate and disable all of the physical and snapshot standby databases in the configuration. The example uses 10 seconds. After an immediate failover completes, all the standby databases in the configuration, regardless of their type, are disabled. For manual failover, the observer is started and communicating with the target standby database. Check the spelling of your keyword search. status before the crash. Since the observer is a specialized instance of a dgmgrl session, the observer host should be installed with either the Oracle Client Administrator software or the full Oracle Database software stack. OBSERVER command, if this directory does not have the WAIT option, broker waits for the amount of PRIM> ALTER DATABASE COMMIT TO SWITCHOVER TO PHYSICAL STANDBY WITH SESSION SHUTDOWN;
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