Disabling fast-start failover does not stop the observer. The new primary database starts transmitting redo data to the new standby database. A switchover is a role reversal between the primary database and one of its standby databases. Observer sites monitor the fast-start failover environment. This walkthrough uses Maximum Availability mode to achieve "zero data loss". To maximize the benefits of FSFO, the observer should run on a different host than the primary and standby databases. If the database is not managed by Oracle Clusterware, This file In order to maintain separation of Broker and non-Broker activity, a second static service is recommended. fast-start failover succeeds, if a post-callout script is specified in the fast-start Now let's test switchover in the other direction. The observer host is 'observer.demo.org'. For each observer, the V$FS_FAILOVER_OBSERVERS view provides the Each observer has its own log file. When the primary database and the target standby database regain network connectivity, the broker will disable fast-start failover for the entire broker configuration. In maximum protection mode, set the LogXptMode database property to SYNC (note that in maximum protection mode, a far sync instance cannot be used to ship redo to a standby). A failover may or may not result in data loss depending on the protection mode in effect at the time of the failover. During an immediate failover, the broker performs the failover steps described in How the Broker Performs an Immediate Failover Operation. the names of the scripts created in the previous step. You cannot create the standby DB system in a different AD from the primary DB system. The rest of this section provides examples of using DGMGRL SHOW commands to display fast-start failover information and includes sections describing the following views: The DGMGRL SHOW FAST-START FAILOVER command displays all the fast-start failover related information. On the Data Guard Failover Confirmation page, specify the type of failover that you want to perform: Complete: All available redo is applied on the standby database. fast-start failover, you can issue the DGMGRL SHOW FAST_START FAILOVER, In this case, the FS_FAILOVER_STATUS and FS_FAILOVER_OBSERVER_PRESENT columns will appear as shown in the following table and fast-start failover will not occur: Oracle Database Reference for more information about the V$DATABASE view. To switchover to a standby that is not the current failover target: John Smiley [jrsmiley@gmail.com] is a persistent storage architect for a major online retailer. This support note is available at http://support.oracle.com. Then, on the Fast-Start Failover Change Mode page, click Enabled. 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. Step:1 Check the database role and open_mode The broker continuously monitors for all sessions that are connected Connect to the target standby database and issue the FAILOVER command to perform a failover, specifying the name of the standby database that you want to become the primary database: Specify the optional IMMEDIATE clause to perform an immediate failover if any of the following conditions are true: An ORA-752 error has occurred at the standby database, An ORA-600 [3020] error has occurred at the standby database and Oracle support has determined that it was caused by a lost write at the primary database. 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 physical and snapshot standby databases will have to be re-created from a copy of the new primary database. Step-by-step instructions for manual reinstatement are described in Reenabling Disabled Databases After a Role Change. file (fsfo.dat). 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. If the value is zero, the standby must PRIM>STARTUP MOUNT; 1. Goal. 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). In the following example, a service named sales is configured to be active in the PHYSICAL_STANDBY role on the primary database NORTH. The Oracle Database 10g FSFO observer is limited to using the default username and password defined in the wallet. Now it will return PRIMARY. Another standby database that does not have connectivity with the primary database, fast-start failover is disabled for this database. SQL Apply on all other bystander standby databases automatically begin applying redo data received from the new primary database. 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. If you re-create the old primary database, it must be created as the standby type of the old standby database. They must be re-created before they can serve as standby to the new primary database. With increased latency comes decreased throughput; however, in some cases the difference in throughput may be made up by increasing parallelism. Disabling Fast-Start Failover Using DGMGRL. ERROR: Unable to verify the graphical display setup. Among many benefits of using this utility, I highlight that while using it, it will not need manual intervention to recover the databases or eventually a switchover in case the primary database becomes unavailable. Execute the following on primary database NORTH: Execute the following on the physical standby database SOUTH: If the broker now performs a switchover or failover, it automatically starts the SALES service on the correct database, based on the database's role. In such a case, no attempt is made to transmit any unsent redo from the cascader to the terminal standby. Notice that the former primary is now disabled. There can be up to four Reinstating the Former Primary Database in the Broker Configuration for more information about reinstatement. The reduced need for manual intervention can increase availability without increasing management costs. Choose a value high enough to avoid false disconnects from intermittent network trouble. There are normally two situations when this operation will be performed: a planned outage for maintenance of the primary database or disaster recovery. Getting the Oracle Net configuration right is one of the key factors in a successful FSFO deployment. Thus, the validity of the values of these properties is not verified until after the switchover. The command fails if the file does not exist. The SHOW CONFIGURATION command will show you which databases can be reinstated and which databases must be re-created. In an Oracle Data Guard configuration, the SRVCTL -startoption and -role are updated after switchover to reflect the current open mode and database role on the new primary and standby databases. See Troubleshooting Problems During a Switchover Operation for more information. In the media recovery phase, Flashback Database applies redo to bring the database up to the standby_became_primary_scn. It will return PRIMARY, You can also specify a list of ORA- errors that will initiate FSFO failover. This is the recommended method for disabling fast-start failover. observer_hostname.log. 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. Data Guard Switchover/failover to standby The standby database will be activated to serve as the primary database at some point in its life cycle. to set the time taken to detect a failure on the primary database: Set the FastStartFailoverThreshold This is true regardless of the settings for the FastStartFailoverPmyShutdown and FastStartFailoverAutoReinstate configuration properties. Immediate Failovers in Configurations Using Cascaded Standbys. The act of switching roles should be a well-planned activity. 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. 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. usually within three seconds if fast-start failover is enabled. To avoid the overhead of recording every change to every block, Flashback Database takes a "fuzzy" snapshot every 30 minutes and only records the before-image block upon its first change since the last snapshot. 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. directory. directory has the same permissions as its parent directory. observer is still in contact with the standby. REINSTATE REQUIRED is present only after fast-start failover has occurred and shows on both the new primary database and the database undergoing reinstatement. To start an immediate failover, use the DGMGRL FAILOVER TO database-name IMMEDIATE command. The broker initiates a failover after the number of seconds specified by this Database services can be configured to be active in specific database roles on Oracle RAC databases and on single-instance databases managed by Oracle Restart. In fact, failovers are so reliable, fast, and simple that switchovers become the exception rather than the rule. When querying the V$DATABASE view, pay special attention to the following: The FS_FAILOVER_STATUS column, which can contain the values described in Table 6-2. 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 . The default value is ALL. Use the FastStartFailoverTarget configuration property on the current primary database to specify one or more fast-start failover targets. exit. drain_timeout amongst the active services. Note that a switchover operation may be started before the specified wait configuration property. multiple, inexpensive servers is the basis for the failover and other fault-tolerance features that RAC provides. Immediate Failovers in Configurations Using Far Sync Instances. SHOW OBSERVER command to confirm that the switch took place. 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. You may failover to a snapshot standby database. 2. 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). Immediately after issuing command in step 2, shut down and restart the standby instance STAN: Now that we know switchovers work, it's time to test failovers. Sign in to Azure When a serious condition uniquely known to an application is detected, the application can call the DBMS_DG.INITIATE_FS_FAILOVER function to initiate an immediate fast-start failover. Commands For Managing Observers on Multiple Configurations. When this property is set to NONE, the broker will disable all bystander standby databases without checking whether they have applied more redo data than the new primary database. ORACLE instance shut down. This list describes conditions in which the broker cannot automatically reinstate the former primary database. If the configuration is not failable, the DBMS_DG.INITIATE_FS_FAILOVER function returns an ORA error number (it does not signal an exception) informing the caller that a fast-start failover could not be performed. If these parameters are modified outside of Broker, it raises a warning. To disable fast-start failover, use the Fast-Start Failover wizard in Cloud Control or the DGMGRL DISABLE FAST_START FAILOVER [FORCE] command. db_domain . The steps in this section describe the tasks involved to perform a manual failover. When using Maximum Availability mode, consider lowering this to reduce the time commits block when the standby becomes unavailable. To protect the files, it's good practice to store them in separate filesystems. command does not have a network connection to the primary database. required permissions, DGMGRL reports an error. 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. Therefore, the target standby never falls behind the primary These commands can be issued from the DGMGRL command line, but it is not necessary to log on prior to using them. isolated. Oracle Data Guard Concepts and Administration provides information about setting up the databases in preparation of a switchover. You can use Cloud Control or DGMGRL, to perform either a complete (recommended) or an immediate failover. This action will result in loss of data and the possibility of two databases in the configuration simultaneously assuming the primary database role. 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. Create a unique connect alias for each database. callout configuration file. If the database is managed by Oracle Clusterware, broker does not open any of the The example uses 10 seconds. Another good test is to simulate network failures that leave the primary up, but isolated from the failover target standby and the observer. The OberverPingRetry property specifies the number of The word ALL cannot be used as a group name because it is a reserved keyword. 2) Switchover/Failover option is disabled on Enterprise Manager.What are the steps to enable it so that I can do Switchover/Failover operation using OEM. Do not use Shared Server (formerly MTS) for Data Guard. Make sure everything is working before moving on. A failed ping is a ping to you need to make the primary database available, first confirm that a You have done a failover to your Standby database so it becomes the new Primary. The FS_FAILOVER_STATUS column in the V$DATABASE view for the target standby database displays a reason why fast-start failover cannot occur. DG_BROKER_START is set to TRUE and DG_BROKER_CONFIG_FILEn are set correctly SQL> sho parameter broker switch does not happen until the next time the primary contacts the target standby, The following table summarizes which standby types are supported in which protection modes when fast-start failover is enabled. An alternative is to enable flashback database on the primary (and the standby if desired) so in the event of a failover, the primary can be flashed back to the time before the failover and quickly converted to a standby database. Depending on the failover and the types of standby databases involved, some of the databases may need to be reinstated or re-created. Broker maintains these parameters by issuing ALTER SYSTEM commands as appropriate during role transitions, database startup/shutdown, and other events. the current working directory. This list describes how the overall Oracle Data Guard protection mode is handled after a manual failover (complete or immediate). 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. If that metadata is pushed out, Oracle can no longer find a fuzzy snapshot so it will not be able to flash back. If clients are already configured to automatically time out and reconnect if they don't get a response from the database, a simple but effective approach is to use a network alias (e.g. ObserverPingRetry configuration properties. stored in the specified path using the default file names. name of the observer log file is However, there may be exceptions to the recommendation to choose a physical standby database as the target standby database. 4. Thus, the command-line prompt on the observer computer does not The FS_FAILOVER_OBSERVER_PRESENT column displays YES for the target standby database. RAM). A complete failover also attempts to avoid disabling any standby databases that were not the target of the failover, so that they may continue serving as standby databases to the new primary database. It is important that all SRVCTL add service options be identical on all the databases so that the services behave the same way before and after a role change. All standbys other than the failover target are considered bystanders (v$database.fs_failover_status = 'BYSTANDER'). The syntax for the configuration declaration is: The definition for each broker configuration is: The configuration-name can be different from the name defined in the metadata of the Data Guard Broker configuration. SUSPENDED is cleared when connectivity with the primary database is restored. It is also supported for fast-start failover to physical standbys in maximum availability data protection mode. To allow the database to register with the Data Guard listener, the listener endpoint must be added to the database's local_listener parameter. This is In previous releases, OCI and ODP.NET clients receive FAN notifications via Oracle Advanced Queuing (AQ). configuration named ConfigurationSimpleName. Perform SWITCH LOGFILE if necessary. A fast-start failover to the target standby database fails. A fast-start failover occurred because a user-configurable condition was detected or was requested by an application by calling the DBMS_DG.INITIATE_FS_FAILOVER function. If you intend to switch back to the original primary database relatively soon, you may allow the physical and snapshot standbys to remain disabled. is guaranteed to lose no more than the amount of there is a lost network connection, be aware that the observer may attempt a 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. The ObserverOverride and ObserverReconnect properties allow you additional control over the connection to the primary. To start a switchover using Cloud Control, select the standby database that you want to change to the primary role and click Switchover. If it reconnects to the primary database before the standby agrees to fail over, then the master observer will stop attempting to initiate a fast-start failover. Determine the number and size of the Online Redo Log files (ORLs). the current working directory, Uses standard output for displaying the observer logs. Reinstate the original primary database to act as a standby database in the new configuration. The remaining Data Guard-related parameters will be set by Broker later in the walkthrough. Verify the target standby database is ready for failover. 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. Specifying the Observer Configuration File. By default, the broker always determines whether bystander standby databases will be viable standby databases for the new primary when performing a complete failover. Alternatively, if you intend to switch back to the original primary relatively soon, then you may re-enable the disabled standby databases after the switch back. The ObserverReconnect configuration property specifies how often the observer establishes a new connection to the primary database. 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. For example: The default value for the FastStartFailoverThreshold property is 30 seconds and the lowest possible value is 6 seconds. 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. Reinstatement of the failed primary database as a new standby database failed. These primary, only the observers specified in the property can be use in the SET When you are experiencing network disconnections and you issue the DISABLE FAST_START FAILOVER FORCE command on the primary database or a standby database that does not have connectivity with the primary database, fast-start failover may not be disabled for all databases in the broker configuration. You might, for instance, use this to allow the observer to monitor the databases using the same connect identifiers as the client applications. It is then configured to be active in the PHYSICAL_STANDBY role on the physical standby database SOUTH. However the target can receive redo from a far sync instance.). The current primary database must have its LogXptMode property set accordingly and must have standby redo logs configured. See theFlashback Database section above for information on storage requirements. The VALIDATE FAST_START FAILOVER command parses the callout Complete Failovers in Configurations Using Far Sync Instances. The walkthrough begins with a single database that will become the primary of a Data Guard configuration. During a switchover, the primary database transitions to a standby role, and the standby database transitions to the primary role. FB Page:https://www.facebook.com/dbahariprasath/? Logical standby databases that are disabled during failover can be reinstated. In this case fast-start failover cannot occur because the databases are not ready to failover. To proceed, you must first disable fast-start failover using the FORCE option, and then perform a manual failover. A broker configuration can belong to multiple groups. To help you select an appropriate switchover or failover target, use the following DGMGRL commands which perform checks on the database to determine its readiness to complete a role change. The My Oracle Support note 1625597.1 at http://support.oracle.com for information about compatibility requirements between the observer and DGMGRL, Starting Multiple Observers on a Data Guard Broker Configuration. 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. Switches roles between the primary and standby databases. PRIM>SHUTDOWN IMMEDIATE; 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. If the primary is unable to contact the standby after a user specified period of time (NET_TIMEOUT option of log_archive_dest_ n), it drops out of synchronous transfer mode and begins operating as though it were in Maximum Performance mode. OBSERVE-ONLY: Fast-start failover is enabled in observe-only mode. 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. The general approach seems to be CDB level failover to standby , so the failover takes place at CDB to CDB , in an event where a single PDB is experiencing an issue , we will have to failover the whole instance ..this will impact all PDB's on the CDB. Manual failover gives you control over exactly when a failover occurs and to which target standby database. The broker first converts the original primary database to run in the standby role. ob2-host can be a master observer when configuration scripts and checks for errors or misconfigurations. Overall Steps:-. list of the observers that can become the master observer when that They must be re-created from a copy of the new primary database. about starting the observer as a background You cannot create the standby DB system in a different AD from the primary DB system. Updates the broker configuration file to record the change in roles. It automatically recovers the maximum amount of redo data for the protection mode the configuration is operating in. If fast-start failover is enabled, then a switchover can be performed only to the pre-specified target standby database and only if the standby database is synchronized with the primary database or is within the configured lag limit, for the max availability and max performance modes respectively. These FAN events can be used in the following ways: Applications can use FAN without programmatic changes if they use one of these Oracle integrated database clients: Oracle Database JDBC, Oracle Database Oracle Call Interface (OCI), Oracle Data Provider for .NET ( ODP.NET), or Universal Connection Pool for Java. The platform provides comprehensive services such as maintaining and monitoring databases to help the oracle databases in surviving during data corruption. You can query the V$FS_FAILOVER_STATS view on the primary database to display statistics about fast-start failovers that have occurred on the system. You cannot perform a switchover to a snapshot standby database unless you first convert it back to a physical standby database. To verify this change, again query the Database_role column of V$DATABASE. This lets you take advantage of the broker's If the currently configured mode is maximum protection, Cloud Control will downgrade the mode to maximum availability. If it detects that Flashback Database was disabled, either manually, or automatically because Flashback Database discovered a problem, Broker signals "ORA-16827: Flashback Database is disabled". If the database is not enabled, you will not be able to perform a failover to this database. To start an observer as a background process, use the DGMGRL occur. This document only talks about switchover involving physical standby database. The real test of the configuration is a successful role transition in both directions with both switchover and FSFO failover. The pre-callout script 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 Set this property for the primary and target standby database if you want the observer to use a different connect identifier than that used to ship redo data (that is, the connect identifier specified by the DGConnectIdentifier property). The observer does not need to coordinate fast-start failover when fast-start failover is disabled, so the primary and target standby do not nominate a master observer until fast-start failover is enabled. For example: The following example shows the fast-start failover information for the DRSolution configuration: The following SHOW OBSERVER command displays information about multiple observers in the DRSolution broker configuration. alter system set standby_file_management=auto; This parameter must be set before the primary can be opened in Maximum Availability mode.
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