DGMGRL> show configuration Configuration - CDB01_fraad1_CDB01_fraad3 Protection Mode: MaxAvailability Members: CDB01_fraad1 - Primary database CDB01_fraad3 - (*) Physical standby database Here's a one-liner observer startup for *nix. To stop the observer, see Stopping the Observer. Rather, fast-start failover will be enabled in accordance with the current protection mode. Starting Multiple Observers On a Single Host. They must be re-created from a copy of the new primary database. During a complete failover, the broker performs the failover steps described in How the Broker Performs a Complete Failover Operation. If you have not used the SET ObserverConfigFile command after starting the current DGMGRL client, then the result will always be: ObserverConfigFile=observer.ora. In a separate terminal session, verify the configuration. If the service has been configured to start automatically (-policy AUTOMATIC), then the service will automatically start only after a database role change. Broker stores it configuration information in a mirrored set of files outside the database. Initiate the switchover on the primary database PRIM: required permissions, the admin folder is created Metadata for the fuzzy snapshot is stored in the flashback log itself. Create a pre-callout script, or a post-callout script, or both. The minimum allowable limit is 10 seconds. Once fast-start failover is enabled, the broker will ensure that fast-start failover from another DGMGRL session. 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. For example: Ordinarily the observer connects once to the primary and does not attempt to reconnect unless the connection has failed. To start the observer with DGMGRL, issue the following Whenever possible, you should switch over to a physical standby database: If the switchover transitions a physical standby database to the primary role, then: The original primary database will be switched to a physical standby role. If the specified log file is not accessible, or the LOGFILE IS option is not used, then the observer output is sent to standard output. For example: Using DGMGRL, you can do this by examining the output of the SHOW CONFIGURATION LAG. In the previous article, we have seen switching the role of Primary and standby database and failover Primary role to Standby database manually. The following example displays the contents of the fast-start failover Issue the following SRVCTL commands so that both databases in the Data Guard configuration know about the two potential services for each database: To start things up initially, you must manually start the services on the right node. 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. Restarts the new standby (former primary) database if the switchover occurs to a physical standby database, and Redo Apply begins applying redo data from the new primary database. PRIM>connect /@PRIM as sysdba After step 3 completes, you can open the new Primary database STAN: Client-side broker The broker verifies the state and status of the databases to ensure that the switchover transitioned the databases to their new role correctly. If both of those observers are unavailable, the observers Restore - Flashback Database restores the datafiles to the closest snapshot prior to the specified SCN. Contains the callout configuration file, pre-callout script, Overview of Switchover and Failover in a Broker Environment. In maximum availability mode, the behavior depends on the value of the 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. 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. This allows Data Guard to remain functional during maintenance periods when the application listeners are down. Configure the TNSNAMES.ORA file on the observer system so that the observer is able to connect to the primary database and to the pre-selected target standby database. to set the time taken to detect a failure on the primary database: Set the FastStartFailoverThreshold 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. This section describes how to configure and verify each prerequisite. (Yes, bystanders need Flashback Database too). Make sure that your OS environment on the standby is setup. Enable Active Data Guard for read-only workloads. It will also alert you to databases that have had Flashback Database disabled at some point after FSFO was enabled. We'll start with switchovers. A single-instance database must be registered with Oracle Restart in order to publish FAN events via ONS. is guaranteed to lose no more than the amount of 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. If the PreferredObserverHosts property is set for the current Each group that you define must have at least one broker configuration. At a minimum, you must set db_unique_name. Make sure the last redo data transmitted from the Primary database was applied on the standby database. The real test of the configuration is a successful role transition in both directions with both switchover and FSFO failover. The configuration and database status report the same error messages as are returned when there is only one registered observer. This example shows the verbose mode of the 'show configuration' command that provides FSFO-specific information. Data Guard Broker - Controls the creation and monitoring of Data Guard. The command fails if the file does not exist. It behaves similarly to START OBSERVING and STOP OBSERVING to operate on all the configurations defined in the observer configuration file. To enable fast-start failover with DGMGRL, issue the ENABLE FAST_START FAILOVER command while connected to any database in the broker configuration, including on the observer computer. observer immediately begins monitoring the status and connections to If you want to use one Oracle home to start multiple observers, with each observer monitoring a different fast-start failover configuration, use the FILE qualifier to specify a unique observer configuration file location for each configuration to be monitored. To perform specified actions before or after a fast-start failover 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. issue commands and interact with the broker configuration. You can use the broker's reinstate capability to make a failed primary database a viable standby database for the new primary. Add the wallet location and override to sqlnet.ora. It may be possible to convert the old Primary into a Standby database now instead of having to do a time consuming duplicate again. The subdirectories that DGMGRL creates under this directory will also have the The foundation of FSFO is Data Guard - a primary and at least one standby. 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. See Disabling Fast-Start Failover. If the observer finds that the database is no longer the primary, it will attempt to reinstate it as the failover target standby. If the Oracle Data Guard configuration is operating in maximum protection mode, the broker does not allow a switchover to occur to a logical standby database. 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. Your email address will not be published. A number of prerequisites must be met on the primary in order to use Fast-Start Failover. Enabling Fast-Start Failover Task 1: Determine Which of the Available Standby Databases is the Best Target for the Failover, Enabling Fast-Start Failover Task 2: Specify Target Standbys with the FastStartFailoverTarget Configuration Property, Enabling Fast-Start Failover Task 3: Determine the Protection Mode You Want, Enabling Fast-Start Failover Task 4: Set the FastStartFailoverThreshold Configuration Property, Enabling Fast-Start Failover Task 5: Set Other Properties Related to Fast-Start Failover (Optional), Enabling Fast-Start Failover Task 6: Enable Additional Fast-Start Failover Conditions (Optional), Enabling Fast-Start Failover Task 7: Using DGMGRL or Cloud Control, Enabling Fast-Start Failover Task 8: Start the Observer, Enabling Fast-Start Failover Task 9: Verify the Fast-Start Failover Environment. FSFO configurations in Maximum Performance mode may limit potential data loss by specifying the maximum allowable age of transactions that are lost during a failover. 2. ORACLE instance shut down. However, you do have the option of specifying a name and location for the observer configuration file. Another good test is to simulate network failures that leave the primary up, but isolated from the failover target standby and the observer. Then set the configuration protection mode to maximum availability. This may take a few minutes. To start an immediate failover, use the DGMGRL FAILOVER TO database-name IMMEDIATE command. By default, a fast-start failover is done when both the observer and the standby cannot reach the primary after the configured time threshold (FastStartFailoverThreshold) has passed. Ensure SPFILE is used SQL> sho parameter spfile 2. FAN server-side callouts can be configured on the database tier. Note: the FSFO observer version must match the database version. The existence of a .suc file, If the configured data loss guarantee cannot be upheld, file also declares broker configurations and defines configuration In case of primary database failure, you will need to perform failover to transition the standby database to the primary role. 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. The observe-only mode for fast-start failover enables you to test how fast-start failover will work in your environment. You can create two callout configuration scripts, a Fast-start failover will not be attempted for the other types of database shutdown (NORMAL, IMMEDIATE, TRANSACTIONAL). Both Cloud Control and the DGMGRL CLI will do this automatically as part of failover. Oracle Data Guard provides the ability to create and maintain Standby databases at one or more sites These protect Oracle databases from database and server failures as well as site disasters Failover to one of the alternate sites can be set to happen automatically (fast-start failover) or manually if the primary database is not usable See Enabling Fast-Start Failover for more information. STANDBY> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY; A good method to determine Flashback Database storage requirements is to enable Flashback Database and observe the amount of storage it uses during several peak loads. If the protection mode was at maximum protection, it is reset to maximum performance. required permissions, DGMGRL reports an error. Once Flashback Database has succeeded, the observer will convert the database to a standby, bounce it, and begin apply services. Input commands are shown in shaded boxes in normal text. DGConnectIdentifier, "Scenario 9: Performing a Switchover Operation" for an example of using the VALIDATE DATABASE command to show a database's readiness to complete a role switchover, "Scenario 10: Performing a Manual Failover Operation" for an example of using the VALIDATE DATABASE command to show a database's readiness to complete a role failover. Subsequent changes to the same block during the same snapshot are not recorded. 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 command START OBSERVER IN BACKGROUND. In this mode you will need to consider how much data loss is acceptable in terms of seconds and set the FastStartFailoverLagLimit configuration property accordingly. On the Oracle Data Guard Overview page, click Database must be reinstated. If they are isolated from each other, then you must first disable fast-start failover by using the FORCE option, and then stop the observer. An observer is a separate OCI client-side component that run on a different computer from the primary and standby databases and monitors the availability of the primary database. See Manual Failover for complete information about manual failovers. If the primary database is an Oracle Real Application Clusters (Oracle RAC) database, the master observer will attempt to connect to one of the remaining primary instances. You cannot create the standby DB system in a different AD from the primary DB system. Default value is 10 miliseconds. the location of the observer log file, and the location of the observer runtime data 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. DGMGRL can be used to manage multiple observers in a group of broker configurations. In this case fast-start failover cannot occur because the databases are not ready to failover. instructions for the DGMGRL command-line interface. When enabled, re-create the standby database. Tasks that must be performed before and after a fast-start failover This document describes how to setup clients to connect to Data Guard databases (primary and standby) and configure automatic client failover such that in case there is role change due to switchover or . 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 the credentials cannot be obtained, then the attempted command fails (but only for the broker configuration whose credentials have not been obtained). Disabling fast-start failover with the FORCE option when connected to the target standby database guarantees that fast-start failover will not occur. 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. maximum availability and maximum performance modes, to avoid a You cannot perform a switchover to a snapshot standby database unless you first convert it back to a physical standby database. If a database must be re-created from a copy of the new primary database, it will have the following status: Re-create the standby database from a copy of the primary database and then reenable it, as described in How to Re-create and Reenable a Disabled Database. Queries and DML will continue to run - only sessions that commit will block. fast-start failover through Cloud Control. Oracle Database 11g observers are incompatible with 10g databases and vice-versa. However the target can receive redo from a far sync instance.). PDBs. Some of the statistics that can be monitored are as follows: LAST_FAILOVER_TIME that shows the timestamp of last fast-start failover, LAST_FAILOVER_REASON that shows the reason for the last fast-start failover. When fast-start failover is enabled, the primary and standby randomly choose one of the registered observers to be the master. Enabling fast-start failover does not trigger a failover. If fast-start failover is If the failover target database is an Oracle RAC physical or snapshot standby database, the broker directs Oracle Clusterware to restart all instances that may have been shut down prior to the failover. For example: In the following example, assume the network between the primary database and the observer has failed. The services include switchover, switchback and failover. The following table summarizes which standby types are supported in which protection modes when fast-start failover is enabled. Disabling fast-start failover without the FORCE option can succeed only if the database on which the command is issued has a network connection with the primary database and if the primary database and target standby database have a network connection. If the client uses remote ONS subscription, the client must specify the hostname and port of the ONS daemon(s) of the primary database and each standby database. If the value is non-zero, failover is possible any time the standby database's apply services. 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. An spfile is required to persist these changes. Clusterware agent that the failover completed, the Oracle Clusterware agent opens PDBs There are two types of failover operations: Graceful or "no-data-loss" failover and Forced or "minimal-data-loss" failover. After the database has been re-created, enable broker management of the re-created standby database by using the DGMGRL ENABLE DATABASE command. One is the master 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. Each database in a Data Guard configuration must have a unique name. Disabling fast-start failover does not stop the observer. The broker never automatically reinstates the former primary database if a fast-start failover was initiated because a user configuration condition was detected or was requested by an application calling the DBMS_DG.INITIATE_FS_FAILOVER function. 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. After FSFO is enabled, Broker will continue to check that Flashback Database is enabled during health checks. By default, the observer creates this file in the current working directory when it is started and names the file fsfo.dat. A fast-start failover to the target standby database fails. milliseconds. Data Guard broker does not manage or store credentials. 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. The broker reinstates bystander standby databases that were disabled during a failover as standby databases to the new primary database. This property is measured in Before enabling fast-start failover in data guard broker, the only required precondition is enabling Flashback Database. If you are not using Oracle Clusterware or Oracle Restart, then you must create static service names so that the observer can automatically restart a database as part of reinstatement. This is a good time to enable FSFO to make sure that all of the prerequisites have been met. The minimum value of ObserverPingInterval is 100 DG_BROKER_START is set to TRUE and DG_BROKER_CONFIG_FILEn are set correctly SQL> sho parameter broker fsfocallout.ora. The failover was to a logical standby database. Observer sites monitor the fast-start failover environment. In this case, no attempt is made to transmit any unsent redo from the far sync instance to the target physical standby prior to converting the physical standby into a primary database. CONNECT command. Use the VALIDATE STATIC CONNECT IDENTIFIER command to ensure the static services have been configured correctly. ensure that it has the required permissions. You can optionally indicate the database health conditions that should cause fast-start failover to occur. OBSERVE-ONLY: Fast-start failover is enabled in observe-only mode. Notice that the former primary is now disabled. However, if the standby has had contact from the primary within the period of time specified by the FastStartFailoverThreshold property, the standby prevents the failover attempt. time specified in the WAIT option. If the failover target is a logical standby database, the original primary database and all physical and snapshot standby databases in the configuration will be disabled. In this example, there are 3 ORLs with a max group# of 3. On the new primary database STAN, perform a SWITCH LOGFILE to start sending redo data to the standby database PRIM. file (fsfo.dat). The command SHOW FAST_START FAILOVER shows a list of registered observers and indicates which one is the master. Initiate the failover on the standby database STAN: SQL>connect /@STAN as sysdba SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE FINISH; SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY; 2. DG BrokerDG BrokerData Guard BrokerOracleDGRMAN Duplicate . Stores files related to the observer and callout configuration. You can enable fast-start failover from any site while connected to any database in the broker configuration. time specified by maximum configured The following sections provide more information about the fast-start failover environment: When Fast-Start Failover Is Enabled and the Observer Is Running, Restrictions When Fast-Start Failover is Enabled, Shutting Down the Primary Database When Fast-Start Failover Is Enabled, Performing Manual Role Changes When Fast-Start Failover Is Enabled. Performing failover : Step 1: Check Standby Database role. 4. The broker allows a complete failover to proceed as long as there are no errors present on the standby database that you selected to participate in the failover. all of the same type (all physical or all logical standby databases), choose the standby The time interval starts when the observer first loses its connection to the primary database. VALIDATE In order to maintain separation of Broker and non-Broker activity, a second static service is recommended. You can issue a An immediate failover is the fastest type of failover. there is a lost network connection, be aware that the observer may attempt a 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. This support note is available at http://support.oracle.com. If the status is SUCCESS, you're ready to start testing role transitions. is only possible when the configured data loss guarantee can be The ObserverPingInterval Make some new changes and verify that they are preserved after failover. Verify the target standby database is ready for failover. This is because the -role qualifier is taken into account only by Data Guard broker, and at database startup. Disabling Fast-Start Failover Using DGMGRL. If the broker performs a switchover or failover, then it starts the service SALESRW or SALESRO based on the current role of the database. 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. command does not have a network connection to the primary database. By default, the observer will initiate failover to the target standby if and only if ALL of the following are true: Oracle Database 11g Rel 1 introduced user configurable failover conditions that can trigger the observer to initiate failover immediately. In a Managed Instance with multiple databases in Azure we can have high availability. Once the observer has initiated a fast-start failover, the primary database shuts down automatically. Upon detecting the break in communication, the observer attempts to reestablish a connection with the primary database for the amount of time defined by the FastStartFailoverThreshold property before initiating a fast-start failover. When the configuration has more than one registered observer, if the primary and target standby databases stay connected but the connection to the master observer is lost, then the broker tries to nominate a backup observer as the new master observer. Specifying Preferred Observers Based on Current Primary. For example, if a physical standby database was in the APPLY-OFF state, it will remain in the APPLY-OFF state. It's a good idea to have at least two hosts configured to run observers so that one can take over if the other fails. the observer on ob2-host to become the master Database hosts are referred to as "a" and "b" hosts and the databases themselves are referred to as the "a" and "b" databases. POTENTIAL DATA LOSS: Fast-start failover is enabled with some data loss. Step 4: Enable Fast-Start Failover Now we are ready to enable FSFO: DGMGRL> enable fast_start failover; Enabled in Zero Data Loss Mode. The connect-identifier is a TNS alias defined in tnsnames.ora through which all instances of all databases in this Data Guard broker configuration can be reached. Testing FSFO failover requires simulating loss of the primary. Broker Configuration Has Multiple Registered Observers. Create a unique connect alias for each database. You might, for instance, use this to allow the observer to monitor the databases using the same connect identifiers as the client applications. Any standby database that was disabled by the broker must be reinstated or re-created, as described in Reenabling Disabled Databases After a Role Change, before it can be a standby database for the new primary database. SHOW OBSERVERS [FOR fg_group_name ] shows information about observers for all configurations in the specified group. The foundation of FSFO is Data Guard - a primary and at least one standby.

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