All physical and snapshot standby databases will be disabled and must be re-created from a copy of the new primary database after a switchover to a logical standby database. There are two types of failover operations: Graceful or "no-data-loss" failover and Forced or "minimal-data-loss" failover. In maximum protection mode, an automatic failover is always possible because the the primary and target standby databases. Once Flashback Database has succeeded, the observer will convert the database to a standby, bounce it, and begin apply services. DGMGRL> show configuration Configuration - CDB01_fraad1_CDB01_fraad3 Protection Mode: MaxAvailability Members: CDB01_fraad1 - Primary database CDB01_fraad3 - (*) Physical standby database Use the Cloud Control Fast-Start Failover wizard or the DGMGRL ENABLE FAST_START FAILOVER command to enable fast-start failover. (Note: 11.1.0.7 adds the StaticConnectIdentifier Broker database property to allow you to specify a different service name.) This table describes the optional database properties that you can set. The mode can have one of the following values: DISABLED: Fast-start failover is disabled. 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. For switchovers, understanding all of the factors can simplify the choice of which standby database to consider as your new primary database. The default value is 30 seconds and the lowest possible value is 5 seconds. You can also reinstate bystander standby databases that were disabled during a failover operation. Whereas a switchover to a logical standby database will invalidate and disable all of the physical and snapshot standby databases in the configuration. The broker controls the rest of the switchover. Use the callout configuration file and script The following table summarizes which standby types are supported in which protection modes when fast-start failover is enabled. Twitter:https://twitter.com/hariprasathdba, In Broker will set the primary to use asynchronous log transport by default. have received all the redo data the primary has generated in order for automatic failover to Log into the new primary and verify that the changes made it across. Oracle 12c-Step by Step Manual Data Guard Switchover, Manual Upgrading Oracle Database From 11.2.0.4 to 12.2.0.1, Automatically Terminated The Blocking Session By Setting MAX_IDLE_BLOCKER_TIME, Apply Patching On Oracle 21c Database Release Update 21.7.0.0.0, Oracle 21c Point In Time Recovery of Pdb Database, Oracle 21c Cloning a PDB Database Using Sqldeveloper Tool. The subdirectories that DGMGRL creates under this directory will also have the 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. Note that primary and standby databases must be licensed for Oracle RAC or Oracle Active Data Guard in order to use Application Continuity. The group of broker configurations to be managed is declared in the observer configuration file. For information about event notification and database connection failover support for global services, see the Oracle Database Global Data Services Concepts and Administration Guide. 2. This example shows the verbose mode of the 'show configuration' command that provides FSFO-specific information. Aug 2022 - Present6 months. times that the observer retries a failed ping before it initiates a Set both these properties to achieve a primary failure detection time of 1 The only exception to this is failovers to snapshot standby databases. To stop the observer when fast-start failover is disabled, the primary database must be running. You have done a failover to your Standby database so it becomes the new Primary. You can manage observers through either the Oracle Data Guard Overview pages in Cloud Control or using DGMGRL commands. $DG_ADMIN/config_ConfigurationSimpleName/callout The reinstated database acts as the fast-start failover target for the new primary database, making a subsequent fast-start failover possible. FB Page:https://www.facebook.com/dbahariprasath/? the names of the scripts created in the previous step. maximum availability and maximum performance modes, to avoid a Notice that the terminal session appears to hang after starting the observer. receives redo data from a far sync instance. In such cases, the failed primary database is reinstated as a physical standby database. A failover to a logical standby database requires that all physical and snapshot standby databases be re-created from a copy of the new primary database after the failover completes. Make sure the last redo data transmitted from the Primary database was applied on the standby database. Although redo transfer is synchronous, Maximum Availability mode allows the primary to remain available if the standby database becomes unavailable for any reason (e.g. Fast-start failover allows the broker to automatically fail over to a previously chosen standby database in the event of loss of the primary database. Permissions Required by the DG_ADMIN Directory. This can be avoided by first disabling fast-start failover with the FORCE option on the target standby. The default name for This configuration property causes the primary database to shut down if fast-start failover is enabled and V$DATABASE.FS_FAILOVER_STATUS indicates the primary has been STALLED for longer than FastStartFailoverThreshold seconds. Enabling fast-start failover in a configuration operating in maximum performance mode provides better overall performance on the primary database because redo data is sent asynchronously to the target standby database. 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. configuration file exists. LinkedIn:https://www.linkedin.com/in/hari-prasath-aa65bb19/ Observer sites monitor the fast-start failover environment. We can always fail over to it or have it happen automatically if for some reason the primary Managed Instance has [] ob2-host can be a master observer when The observer is perfectly satisfied if all of the redo it needs to meet your durability requirements has been received by the failover target. Broker can be configured to initiate failover on any of the following conditions. 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. The column value for V$DATABASE.FS_FAILOVER_STATUS will be SYNCHRONIZED in a configuration operating in maximum availability mode, and it will be TARGET UNDER LAG LIMIT in a configuration operating in maximum performance mode when ready to fast-start failover. You can customize fast-start failover setup for a specific application by using the DBMS_DG PL/SQL package. The remaining Data Guard-related parameters will be set by Broker later in the walkthrough. You can optionally indicate the database health conditions that should cause fast-start failover to occur. Provides an automatic failover environment A fast-start failover to the target standby database fails. Do this prior to every failover test. This property also affects whether the broker skips viability checks of bystander standby databases when a fast-start failover occurs. Create a pre-callout script, or a post-callout script, or both. operation. Step:5Bounce your database and verify database name its open mode and its role. If the target is a snapshot standby database, the broker first converts the database to a physical standby database. Displays when the primary and target standby databases are synchronized and the configuration is operating in maximum availability mode. 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. If you are more concerned about the performance of the primary database than a minimal loss of data, consider enabling fast-start failover when the configuration protection mode is set to maximum performance. For each temporary table, verifying that temporary files associated with that table on the primary database also exist on the standby database. an alias of the broker configuration name. If fast-start failover is already enabled, the Once fast-start failover is enabled, the broker will ensure that fast-start failover The act of switching roles should be a well-planned activity. files to automate tasks that must be performed before and after a fast-start failover Use broker configuration properties to set the time taken to detect a If there are multiple observers, then only one of them is the master observer. environment variable is set and the specified directory has the Observer uses the value of the DGConnectIdentifier property to connect to and monitor the primary and target standby databases. You can use the SHOW CONFIGURATION WHEN PRIMARY IS command to show the redo transport configuration (based on each member's setting of the RedoRoutes property) that would be in effect if the specified database were the primary database. These requirements are supplemental to those described in the documents previously referenced and in the following client-specific guides: Oracle Data Provider for .NET Developer's Guide for Microsoft Windows. directory does not have the required permissions. upheld. If you have not used the SET ObserverConfigFile command after starting the current DGMGRL client, then the result will always be: ObserverConfigFile=observer.ora. Make some new changes and verify that they are preserved after failover. The following list indicates the extent to which fast-start failover is disabled in the broker configuration when the DISABLE FAST_START FAILOVER FORCE command is issued on the primary database, target standby database, and a standby database that is not the fast-start failover target. There can be up to four observers for a single Data Guard configuration. Make sure everything is working before moving on. (See Disabling Fast-Start Failover for important considerations when using the FORCE option.). It is then configured to be active in the PHYSICAL_STANDBY role on the physical standby database SOUTH. 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. You can manually stop a specific observer or all observers. This is because the -role qualifier is taken into account only by Data Guard broker, and at database startup. If groups are not defined, you can still operate on all configurations defined in the file as a whole. Add the primary database and each standby database to the address list. Once an observer is started, no further user interaction is required. If you have an Oracle RAC primary database, consider specifying a higher value to minimize the possibility of a false failover in the event of an instance failure. automatic failover feature in configurations set up for zero data loss protection at any To configure fast-start failover in observe-only mode: Fast-start failover will not be triggered if the primary or standby database is shut down normally. The current primary database must have its LogXptMode property set accordingly and must have standby redo logs configured. Now that we know switchovers work, it's time to test failovers. Verifies that the target standby database is enabled. Verify the target standby database is ready for failover. created when the START OBSERVER command is issued. An immediate failover is the fastest type of failover. Steps for FAILOVER the Dataguard environment 1. In the rare event that a switchover operation fails and you are left with no primary database, retry the switchover command. Before enabling fast-start failover in data guard broker, the only required precondition is enabling Flashback Database. physical standby database. Data Guard uses Oracle Net (SQL*Net) for communication between the primary and standby databases and the FSFO observer. SQL>STARTUP; This is typically done for planned maintenance of the primary system. After the former primary database has been repaired, the observer reestablishes its connection to that database and reinstates it as a new standby database. After step 1 finishes, Switch the original physical standby db STAN to primary role; Now it will return PRIMARY. In the event of a Oracle Database Reference for more information about the V$FS_FAILOVER_OBSERVERS view. This section will help you get started with creating a wrapper script to automatically start and restart the FSFO observer. Flashback Database stores its logs in the Flash Recovery Area (FRA), so the FRA must be large enough to store at least 60 minutes of Flashback Database history. If the protection mode was at maximum protection, it is reset to maximum performance. Look for the desired data in the RAM. 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. operation can be automated using callout scripts. See Setting the Protection Mode for Your Configuration. observer and the others are backup observers. 1. The total storage requirement is proportional to the number of distinct blocks changed during snapshots - e.g. You can switch back to the original primary and then either retry the switchover to the original target standby, or choose another standby in the configuration to switch over to. The observer is the key element that separates Data Guard failover from its pre-FSFO role as the plan of last resort to its leading role in a robust high availability solution. This action may result in two databases in the configuration simultaneously assuming the primary database role should fast-start failover occur. If the target standby database is ready for failover, then the master observer immediately directs the target standby database to fail over to the primary database role. You can also query the V$FS_FAILOVER_STATS view to display statistics about fast-start failover occurring on the system. See Sources of Diagnostic Information for details about the broker's drc* log files. 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. 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. Run the RMAN utility and connect to the target (primary) and auxiliary (new standby). the preferred method for starting an observer. OBSERVER command, if this directory does not have the As a result the observer may still initiate fast-start failover to the target standby database, if conditions warrant a failover. once the target standby database's redo applied point is no longer lagging behind the primary POTENTIAL DATA LOSS: Fast-start failover is enabled with some data loss. See Reenabling Disabled Databases After a Role Change. The following is a sample observer configuration file: Since the broker configuration SALES consists of three databases, Boston, Chicago, and Dallas, with a CONNECT_ID of SALES_P, the SALES_P connect identifier must be defined such that it can reach any instance of any database within the configuration. only. lag is less than or equal to the value specified by the For each broker configuration on which one or more See Reenabling Disabled Databases After a Role Change for more information. Oracle 12c-Step by Step Manual Data Guard Failover. Each observer has its own log file. Database hosts are referred to as "a" and "b" hosts and the databases themselves are referred to as the "a" and "b" databases. PRIM>connect /@PRIM as sysdba session. fast-start failover has not occurred to the target standby database. North_Sales is in the primary role. 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. If fast-start failover is enabled you can still perform a switchover or a manual failover as long as certain conditions are met. Your email address will not be published. data (in seconds) specified by the The command SHOW OBSERVER provides detailed information about registered observers. Verify dmon process is running and broker parameters viz. Data Guard Configuration Details:-. What is true about data guard set up with fast-start failover (FSFO) in Oracle Cloud Infrastructure (OCI)? Reinstatement of the failed primary database as a new standby database failed. This guide uses the naming convention of appending an underscore followed by a letter to the db_name to create the db_unique_name. The platform provides comprehensive services such as maintaining and monitoring databases to help the oracle databases in surviving during data corruption. The configuration and database status report the same error messages as are returned when there is only one registered observer. FSFO can also be used with logical standbys and an FSFO-enabled configuration may have multiple standbys with a mix of physical and logical, but only one standby can be the failover target at any given time. 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). If necessary, you can shut down the primary or target standby database in a fast-start failover environment. The broker first converts the original primary database to run in the standby role. Perform a switchover to a standby database that is not configured as the fast-start failover target, Perform a switchover to the target standby database in a configuration operating in maximum availability mode, unless the standby database is synchronized with the primary database, Perform a switchover to the target standby database in a configuration operating in maximum performance mode, unless the standby database is within the lag limit of the primary database.

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