This prevents a "split brain" condition if a failover occurs since none of the changes made to the isolated primary can be made permanent. A failed ping is a ping to Displays when the primary and target standby databases are synchronized and the configuration is operating in maximum availability mode. operation: Example 6-1 Fast-start Failover Configuration You have done a failover to your Standby database so it becomes the new Primary. To stop an observer currently designated as the master observer, first issue the SET MASTEROBSERVER command to designate a different observer as master observer. If the configuration contains both physical and logical standby databases, consider choosing a physical standby database (that has the least amount of unapplied redo) to be the target standby database. 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. See "Database Service Configuration Requirements" for additional information about how the broker interacts with Oracle Restart. Automatic failover quickly and reliably fails over the standby Autonomous database to the primary database role, without requiring you to perform any manual steps. Set the FastStartFailoverThreshold property to specify the number of seconds you want the observer and target standby database to wait (after detecting the primary database is unavailable) before initiating a failover. If one of these errors has occurred, follow the guidelines in "Resolving ORA-752 or ORA-600 [3020] During Standby Recovery" in My Oracle Support Note 1265884.1 before proceeding. 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. During the failover to the physical standby database, the Oracle 11g DGB performs the following steps: First, it validates that the target standby database is ready to accept the primary role. The existence of a .suc file, When you select a standby database to be the next primary database after a switchover or a failover, there are several factors to consider. 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. North_Sales is in the primary role. 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 word ALL cannot be used as a group name because it is a reserved keyword. There can be up to four observers for a single Data Guard configuration. Flashing back a database occurs in two stages: For FSFO environments, set db_flashback_retention_target = 60 or higher to provide sufficient Flashback Database history for automatic standby reinstatement. 3. first recording that a fast-start failover cannot happen. The Column Value in the following table is consistent across instances in an Oracle Real Applications Clusters (Oracle RAC) environment. This action may result in two databases in the configuration simultaneously assuming the primary database role should fast-start failover occur. Because fast-start failover was not disabled on the target standby database, the observer may still attempt a fast-start failover to the target standby database should conditions warrant a failover. To enable fast-start failover, both the primary and target standby databases must be running and have connectivity, and satisfy all of the prerequisite conditions listed in Prerequisites for Enabling Fast-Start Failover. Instead, Oracle Clusterware opens PDBs on particular instances based on POTENTIAL DATA LOSS: Fast-start failover is enabled with some data loss. Stopping the Observer When There is Only One Observer. configuration file exists. Transitions the target standby database into the primary database role, as follows: Changes the role of the database from standby to primary. The broker preserves the protection mode that was in effect prior to the failover. DNS CNAME) that always resolves to the primary. milliseconds and that of ObserverRetryCount is 10. If fast-start failover is enabled you can still perform a switchover or a manual failover as long as certain conditions are met. fast-start failover operation, the observer checks if a fast-start failover lag is less than or equal to the value specified by the This support note is available at http://support.oracle.com. In addition, a logical standby database may contain only a subset of the data present in the primary database. It must appear as the first part of an observer configuration file. When a primary loses contact with both the failover target and the observer simultaneously, it enters a "stalled" state (v$database.fs_failover_status = 'STALLED') and any sessions still connected to the primary will block on commit. This not only saves time and minimizes problems by automating an otherwise manual process, it exercises your failover and DR procedures with every flip so that you know the FSFO configuration is sound and, in a real emergency, everyone knows what to do. Only the observer can initiate FSFO failover. The rest of this section provides examples of using DGMGRL SHOW commands to display fast-start failover information and includes sections describing the following views: The DGMGRL SHOW FAST-START FAILOVER command displays all the fast-start failover related information. Metadata for the fuzzy snapshot is stored in the flashback log itself. Regardless of the method you choose, the broker coordinates the role transition on all databases in the configuration. If the primary and target standby databases do not have network connectivity or if the database to which you are connected does not have network connectivity with the primary database, consider using DISABLE FAST_START FAILOVER with the FORCE option. the Steps To Congure Oracle 11g Data Guard Physical Standby associate that we give here and check . WAIT option, broker waits for the amount of To stop the observer when fast-start failover is enabled, the primary database and target standby database must be connected and communicating with each other. This can be compared to performing an RMAN restore of the datafiles from a backup taken prior to the specified SCN, but is much faster. To allow the database to register with the Data Guard listener, the listener endpoint must be added to the database's local_listener parameter. On the Data Guard Failover Confirmation page, specify the type of failover that you want to perform: Complete: All available redo is applied on the standby database. For example, if all your physical standbys are also unavailable, then failing over to a logical standby is your only choice. 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). Note: You can also use TNS aliases defined in the tnsnames.ora file when setting the local_listener parameter. created under this directory by DGMGRL will also have the same permissions. Relationship Between Primary, Target Standby, and Observer During Fast-start Failover. Select name,open_mode,database_role from v$database; Step:2 Cancel the MRP process Choosing the standby database with the smallest transport lag can minimize the amount of data loss and in some cases, incur no data loss at all. Only two databases, the primary and the failover target, can be in the FSFO configuration at any given time. After the failover completes, the former primary database is automatically reinstated as a standby database when a connection to it is reestablished, if the FastStartFailoverAutoReinstate configuration property is set to TRUE. connectivity with target standby. These For each temporary table, verifying that temporary files associated with that table on the primary database also exist on the standby database. SUSPENDED is cleared when connectivity with the primary database is restored. It is instructive to watch the alert logs on both databases as well as the observer log after aborting the primary to gain insight into what happens during FSFO failover. Were sorry. If fast-start failover is enabled and the Datafile Write Errors condition is specified, then a fast-start failover is initiated if write errors are encountered in any data files, including temp files, system data files, and undo files. Data Guard Configuration Details:-. STANDBY>connect /@STAN as sysdba If local_listener is already in use, add the Data Guard listener to the list. Determine the number and size of the Online Redo Log files (ORLs). See Troubleshooting Problems During a Switchover Operation for more information. fsfo_hostname.dat. 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. You cannot create the standby DB system in a different AD from the primary DB system. The group of broker configurations to be managed is declared in the observer configuration file. FastStartFailoverThreshold for reference information about the FastStartFailoverThreshold property. configuration named ConfigurationSimpleName. Maximum Availability mode uses synchronous redo transfer and FSFO imposes the additional requirement that the redo is recorded in the standby redo log (SRL) of the target standby (AFFIRM option of log_archive_dest_ n). 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. When the process is complete, the database will be enabled as a standby database to the new primary database, and Cloud Control displays the Oracle Data Guard Overview page. Otherwise, they must be re-created from a copy of the new primary database. operation. During a complete failover, the broker performs the failover steps described in How the Broker Performs a Complete Failover Operation. The default value is ALL. These commands can be issued from the DGMGRL command line, but it is not necessary to log on prior to using them. Set the ObserverPingInterval and Click Failover. Manual failover to the fast-start failover target can be performed without receiving an acknowledgement from the observer. To verify the observer is started and the configuration is ready for 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. Testing FSFO failover requires simulating loss of the primary. If fast-start failover is already enabled, the 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. Table 6-2 FS_FAILOVER_STATUS Column of the V$DATABASE View. Fast-start failover enables the Data Guard broker to rapidly and automatically failover to a previously chosen standby database without requiring manual intervention. STANDBY> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY; document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. Restore - Flashback Database restores the datafiles to the closest snapshot prior to the specified SCN. observer as a foreground process. The "Configuring Authentication" chapter of the Oracle Database Security Guide provides detailed instructions for creating a wallet. second. The former primary database is disabled. Reinstatement restores high availability to the broker configuration so that, in the event of a failure of the new primary database, another fast-start failover can occur. In the media recovery phase, Flashback Database applies redo to bring the database up to the standby_became_primary_scn. If the standby database is not enabled for management by the broker, then the failover cannot occur. 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. Maximum availability SYNC or FASTSYNC or ASYNC, Maximum performance SYNC or FASTSYNC or You cannot perform a manual failover to the target standby database for the same reason. Enabling fast-start failover does not trigger a failover. A fast-start failover to the target standby database fails. 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. Observers should be installed and run on a computer system that is separate from the primary and standby systems. A single-instance database must be registered with Oracle Restart in order to publish FAN events via ONS. Oracle Data Guard is a solution provider to businesses by offering data protection and its disaster recovery along with its high availability. The broker selects a target based on the order in which they are specified on the FaststartFailoverTarget property. 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. STOP OBSERVING, and SET After step 3 completes, you can open the new Primary database STAN: Conditions shown in blue are enabled by default. Learn how your comment data is processed. This is called failover. 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. have received all the redo data the primary has generated in order for automatic failover to If the service has been configured to start automatically (-policy AUTOMATIC), then the service will automatically start only after a database role change. 4. The service can be started on the physical standby only after the redo generated by starting the service has been applied. Facebook:https://www.facebook.com/HariPrasathdba There is little risk in enabling Flashback Database to determine its storage requirements - it can be disabled while the primary is open if necessary. For this build, we will use a single physical standby database. FastStart Failover Ensues: Disaster strikes the primary database and its network connections to both the observer and the target standby database are lost. 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. The commands that can be executed for a group of configurations (as declared in an observer configuration file) are as follows. If the broker performs a switchover or failover, then it starts the service SALESRW or SALESRO based on the current role of the database. 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. It will return PRIMARY, the preferred method for starting an observer. commands. the current working directory. 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. prolonged stall, either the observer or target standby database For more details about managing Redo Apply services using properties, see Managing Log Apply Services. Data Guard uses Oracle Net (SQL*Net) for communication between the primary and standby databases and the FSFO observer. If the switchover transitions a logical standby database to the primary role, then: The original primary database will be switched to a logical standby role. Data Guard. To perform specified actions before or after a fast-start failover file also declares broker configurations and defines configuration Use the VALIDATE STATIC CONNECT IDENTIFIER command to ensure the static services have been configured correctly. performance protection mode with fast-start failover. The broker interacts with Oracle Clusterware or Oracle Restart to ensure that the appropriate database services are active and that the appropriate FAN events are published after a role change. This allows the appropriate Data Guard services, such as redo transport or redo apply, to be started when the database is restarted later for any reason. Synopsis. The pre-callout script If there is more than one standby database in the configuration, you must explicitly set the FastStartFailoverTarget property on the primary database to name one or more candidate target standby databases. must ping the primary database. 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. If you performed a failover or switchover that requires you to re-create the failed primary database or standby databases that were disabled during the role transition, then follow the procedures in the Oracle Data Guard Concepts and Administration chapter, "Creating a Physical Standby Database" and also the Oracle Data Guard Concepts and Administration chapter, "Creating a Logical Standby Database.". present, you must start the observer manually using the following If Flashback Database was enabled on the primary database.If not, the whole setup process must be followed, but this time using the original primary server as the standby. disable fast-start failover with the FORCE option on the 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. Do not attempt to reinstate the old primary database if an ORA-752 or ORA-600 [3020] error has occurred at the failover target. The configuration. Written by authors well-known for their talent with RAC, Pro Oracle Database 11g RAC on Linux . If a non-zero value is specified for the If the Alternatively, use the RedoRoutes property to configure the redo transport mode for the target standby and the database currently in the primary role. The database on which the procedure is called notifies the observer. Stops Redo Apply or SQL Apply on the standby database immediately, without waiting until all available redo data has been applied. The primary database can be reinstated if it had flashback database enabled. file (fsfo.dat). To enable fast-start failover in Cloud Control, use the Fast-Start Failover wizard. We suggest you try the following to help find what youre looking for: This document will guide you through configuringOracle Data GuardFast-Start Failover (FSFO) using a physical standby database. You can register up to four observers to monitor a single Data Guard broker configuration. Here's a one-liner observer startup for *nix. Always try to perform a complete failover first unless redo apply has stopped at the failover target due to an ORA-752 or ORA-600 [3020] error. The SHOW CONFIGURATION command will show you which databases can be reinstated and which databases must be re-created. The master observer never waits for the threshold to expire to perform a fast-start failover in the following situations: If the master observer determines that any of the user-configurable conditions has been detected, then it attempts a fast-start failover. If this operation is successful, a zero data loss failover may be possible even if the primary database is not in a zero data loss protection mode. The default name of the observer runtime data file is Moorestown, New Jersey, United States. For systems with multiple RAID controllers, consider creating SRLs such that their IO is balanced across the controllers. 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. The same process should work for RAC environment as my colleague has . Oracle Corporation recommends that you specify this type of failover. 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. Broker changes database parameters during startup and role transitions via ALTER SYSTEM commands. To disable fast-start failover, use the Fast-Start Failover wizard in Cloud Control or the DGMGRL DISABLE FAST_START FAILOVER [FORCE] command. This results in the observer establishing a new connection to the primary database every 30 seconds. Reinstate the original primary database to act as a standby database in the new configuration. 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. You can switch back to the original Primary database later by performing another switch over. observer_hostname.log. 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). When the configuration has only one registered observer, if the primary and target standby databases stay connected but the connection to the observer is lost, then the broker reports that the configuration is not observed. If reinstatement of a database fails, its status changes to ORA-16795: the standby database needs to be re-created. In a Managed Instance with multiple databases in Azure we can have high availability. If the failover fails for any reason, it could leave the target standby database inoperable, regardless of whether the target standby database is ready to failover. There's a big difference between a system that's FSFO enabled and one that's FSFO ready. SQL>SHUTDOWN IMMEDIATE; If fast-start failover is disabled, then manual failover may still be possible. Goal. Oracle Data Guard work on two database roles Primary and Standby. Initiate the switchover on the primary database PRIM: Download Ebook Oracle 11g 12c Data Guard With Asm Lab Practice A Complete Hands On Lab Practice To Manage A Data Guard . On the new primary database STAN, perform a SWITCH LOGFILE to start sending redo data to the standby database PRIM. A failover is a role transition in which one of the standby databases is transitioned to the primary role after the primary database (all instances in the case of an Oracle RAC database) fails or has become unreachable. 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. alter system set standby_file_management=auto; This parameter must be set before the primary can be opened in Maximum Availability mode. When the primary database and the target standby database regain network connectivity, the broker will disable fast-start failover for the entire broker configuration. The following table summarizes which standby types are supported in which protection modes when fast-start failover is enabled. operation can be automated using callout scripts. ), The RedoRoutes property on a far sync instance if it is being used to receive redo from the primary database and ship redo to the target standby database, The standby database that is the target of fast-start failover, A far sync instance if it is being used to receive redo from the primary database and ship redo to the target standby database, Unless the conditions listed in Performing Manual Role Changes When Fast-Start Failover Is Enabled have been met, To a standby database that is not configured as the fast-start failover target. The word manual is used to contrast this type of failover with a fast-start failover (described in Fast-Start Failover). A normal shutdown prevents a fast-start failover until the primary database and standby database are connected and communicating again. by the current operating system user who is running DGMGRL The subdirectories It is then started and stopped on the primary database. In order to accommodate all load conditions, Oracle recommends having at least one more SRL group than the number of ORL groups of the same size. STAN is now transitioned to the primary database role.Now your PHYSICAL STANDBY Database has become PRIMARY. The reduced need for manual intervention can increase availability without increasing management costs. When this command is issued, the actual This action may result in two databases in the configuration simultaneously assuming the primary database role. The targets are referred to as candidate targets. failure on the primary database. ObserverConfigFile is a DGMGRL session runtime property. The FS_FAILOVER_OBSERVER_PRESENT column, which indicates whether the observer is running and actively pinging the database. Starting with Oracle Database Release 21c, use the DG_ADMIN Data Guard Broker - Controls the creation and monitoring of Data Guard. FastStartFailoverLagLimit The default value is 30 seconds and the lowest possible value is 5 seconds. The observer maintains state information in a file. create the directory specified by the DG_ADMIN environment variable and In an environment where there are multiple observers configured, stopping the master observer is not allowed unless it is the last running observer. For Maximum Availability environments, change this to synchronous. Transitions the target standby database into the primary role, opens the new primary database in read/write mode, and starts redo transport services. mode when the fast-start failover target is a logical or physical standby database that To move the observer to another computer: There is no need to disable fast-start failover when you move the observer. Reinstating the Former Primary Database in the Broker Configuration for more information about reinstatement. Any broker configuration name that is referred to must exist in the configuration declaration section. The following steps all require the database to be in a mounted (not open) state.
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