data guard failover steps

This means that in order for a flashback database operation to succeed, observer and the standby both lose contact with the primary. To run an observer as a background process, use the DGMGRL command START OBSERVER IN BACKGROUND. committing because a fast-start failover may have occurred while it was observer name, host, whether it is the master observer, when it became the master ObserverPingRetry properties before ensure that it has the required permissions. If Flashback Database history is insufficient, the observer will not be able to reinstate and you will have to manually reinstate from backup or by primary duplication. Have a means of notifying someone if standby apply falls too far behind. The information shown by this command is the same as that shown by a SHOW OBSERVER command on each individual configuration. Step:5Bounce your database and verify database name its open mode and its role. Data Guard broker does not manage or store credentials. If a non-zero value is specified for the Oracle Data Guard Concepts and Administration provides information about setting up the databases in preparation of a switchover. If you will be using RMAN to create the standby database, it also needs a static service to restart the database being created. They rely on Oracle Data Guard for high availability databases, with a standby database running in a different availability zone. The name of the callout configuration file is fsfocallout.ora. Use the VALIDATE STATIC CONNECT IDENTIFIER command to ensure the static services have been configured correctly. 3. 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 only a path is specified, the files are WAIT option, broker waits for the amount of During failover, bystanders "follow" the primary by default, flashing back and reapplying redo from the new primary as necessary. When the primary database and the (non-target) standby database regain network connectivity, the broker will propagate its current fast-start failover setting (ENABLED or DISABLED) to the non-target standby. This is The "Configuring Authentication" chapter of the Oracle Database Security Guide provides detailed instructions for creating a wallet. Problems with automatic reinstatement are frequently due to misconfiguration, so let's look at this in a bit more detail. Application calls to DBMS_DG.INITIATE_FS_FAILOVER. It uses these databases as a copy of the . For more details about managing Redo Apply services using properties, see Managing Log Apply Services. The target standby database is enabled and is in the APPLY-ON state. If the observer is stopped abnormally (for example, by typing CTRL/C), restart it and reference the existing fsfo.dat file with the FILE IS qualifier. It's good practice to use separate listeners for application connections and Data Guard connections. failover to the target standby database. Log into the new primary and verify that the changes made it across. This See the Cloud Control online help for more information. A normal shutdown prevents a fast-start failover until the primary database and standby database are connected and communicating again. 1. (See Disabling Fast-Start Failover for important considerations when using the FORCE option.). You can create two callout configuration scripts, a Check the database role,open_mode in standby server. A broker configuration can belong to multiple groups. When fast-start failover is disabled, no observer is called the master observer; all observers have the same functionality. In the media recovery phase, Flashback Database applies redo to bring the database up to the standby_became_primary_scn. For example: Fast-start failover occurs if both the observer and the target standby database lose connection to the primary database for the period of time specified by the FastStartFailoverThreshold configuration property. 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. 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. However, you can change the name or the location of the file if you start the observer using the DGMGRL START OBSERVER command and include the FILE IS qualifier. If you do not want to use the default, you can define a specific group. cannot use a different name for this file. Configure the protection mode. A running observer will follow the primary automatically after a role transition, but a newly (re)started observer won't start if the initial connection is to a down database or one with an out of date or corrupted Broker config file. Perform SWITCH LOGFILE if necessary. Oracle Real Application Clusters Administration and Deployment Guide for information about Application Continuity, The broker simplifies switchovers and failovers by allowing you to invoke them using a single key click in Oracle Enterprise Manager Cloud Control (Cloud Control) or a single command in the DGMGRL command-line interface (referred to in this documentation as, Ensure that the standby database you choose to be the target of fast-start failover has its, Oracle Data Guard Concepts and Administration. 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. If all the databases do not have the same values, SRVCTL attempts to override the values, which will fail on the physical standby database because it is open read-only. on particular instances based on the service configuration. drain_timeout amongst the active services. environment that is guaranteed to either lose no data (when the The new ConfigurationWideServiceName configuration property can be used to simplify setting up this connect identifier. from another DGMGRL session. the observer configuration file is observer.ora. (If there are other conditions, unique to an application, that would warrant a fast-start failover then the application can be set up to call the DBMS_DG.INITIATE_FS_FAILOVER function and start a fast-start failover immediately should any of those conditions occur. Valid values are >= 10. Enabling Fast-Start Failover describes how to start observers as a part of the step-by-step process to enable fast-start failover. 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. Metadata for the fuzzy snapshot is stored in the flashback log itself. Verify there are no active users connected to the databases. Examine the Broker configuration by logging into dgmgrl on the new primary. Observers continuously monitor the fast-start failover environment to ensure the primary database is available (described in When Fast-Start Failover Is Enabled and the Observer Is Running). However, you do have the option of specifying a name and location for the observer configuration file. What is true about Data Guard setup with fast-start failover? Here's a one-liner observer startup for *nix. The observer automatically starts the reinstatement process. The original primary database can now be configured as a standby. Because the broker performs the failover after converting the snapshot standby database to a physical standby database, it is likely that all standby databases in the configuration will still be available as standby databases to the new primary database after the failover operation completes. configuration. For more details about managing redo transport services using database properties, see Managing Redo Transport Services. Bounce your database and verify database name its open mode and its role: SQL> shutdown immediate; ORA-01109: database not open Database dismounted. failover with the FORCE option on the primary database. database. Stopping the Observer When There is Only One Observer. Displays if the standby database's redo applied point does not lag the primary database's redo generation point by more than the number of seconds specified by the FastStartFailoverLagLimit configuration property and the configuration is operating in maximum performance mode. . This may take a few minutes. Verifies that the target standby database is enabled. $DG_ADMIN directory. After the database has been re-created, enable broker management of the re-created standby database by using the DGMGRL ENABLE DATABASE command. What is true about data guard set up with fast-start failover (FSFO) in Oracle Cloud Infrastructure (OCI)? 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. required permissions, the admin folder is created Step:1 Check the database role and open_mode You can specify particular conditions for which a fast-start failover should occur using either Cloud Control or the DGMGRL ENABLE FAST_START FAILOVER CONDITION and DISABLE FAST_START FAILOVER CONDITION commands. The steps in this section describe the tasks involved to perform a manual failover. 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. This section will help you get started with creating a wrapper script to automatically start and restart the FSFO observer. This property cannot be used to prevent the primary database from shutting down if a fast-start failover occurred because a user configuration condition was detected or was requested by an application by calling the DBMS_DG.INITIATE_FS_FAILOVER function. Example 6-2 Sample Observer Configuration File. The Marketplace image that you use to create the VMs is Oracle:Oracle-Database-Ee:12.1..2:latest. Staff support, hardware and software, security (both software and site), network connections, and bandwidth should be equivalent at both sites. If fast-start failover is enabled you can still perform a switchover or a manual failover as long as certain conditions are met. It shuts down or stalls because it is likely a failover has occurred. Once you set these properties, their values persist through role changes during switchover and failover. change tracking enabled, broker enables block change tracking on the new See Sources of Diagnostic Information for details about the broker's drc* log files. For this reason, you should first issue this command on the target standby database. Once Flashback Database has succeeded, the observer will convert the database to a standby, bounce it, and begin apply services. Using Cloud Control, you can view the value of the ApplyLag column for each standby database in the Standby Databases section of the Oracle Data Guard Overview page. Manual failover to the fast-start failover target can be performed without receiving an acknowledgement from the observer. It's secondary job is to automatically reinstate a failed primary as a standby if that feature is enabled (the default). 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. Just be sure to include a Flashback Database history check in the script to provide an option to abort if a failover would require a manual reinstate. Reinstate the original primary database to act as a standby database in the new configuration. For example: The default value for the FastStartFailoverThreshold property is 30 seconds and the lowest possible value is 6 seconds. environment variable to specify the default location for client-side broker files. Verify the primary database instance is open. Group definition this section is optional. command on the observer computer: The observer is a continuously executing process that is After FSFO is enabled, Broker will continue to check that Flashback Database is enabled during health checks. You may failover to a snapshot standby database. You need to consider all of the options at the time you are building your Oracle Data Guard configuration, including factors such as the characteristics of physical standbys versus logical standbys versus snapshot standbys, the network latency to your standby database sites, the computing capabilities at a future primary database site, and so on. If the PreferredObserverHosts property is set for the current 1 second. You want to prevent fast-start failover from occurring because the primary database will resume service soon. On the new primary database STAN, perform a SWITCH LOGFILE to start sending redo data to the standby database PRIM. 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. Enabling fast-start failover does not trigger a failover. Complete Failovers in Configurations Using Far Sync Instances. multiple, inexpensive servers is the basis for the failover and other fault-tolerance features that RAC provides. Stopping a Specific Observer When There are Multiple Observers. If the DG_ADMIN environment variable is not defined, or the When a switchover is started, the primary and standby databases that are involved should have as small a redo lag as possible. If the group name is not provided, then a new observer is started for each broker configuration defined in observer.ora. During a switchover, the primary database transitions to a standby role, and the standby database transitions to the primary role. Performing failover : Step 1: Check Standby Database role. fast-start failover succeeds, if a post-callout script is specified in the fast-start These facilities allow applications written to take advantage of them to receive asynchronous notification of database events, including role transitions. FastStartFailoverLagLimit property. It also requires Flashback Database to be enabled on both the primary and target standby databases. Input commands are shown in shaded boxes in normal text. The observer's main purpose is to enhance high availability and lights out computing by reducing the human intervention required by the manual failover process that can add minutes or hours to downtime. Since the observer is a specialized instance of a dgmgrl session, the observer host should be installed with either the Oracle Client Administrator software or the full Oracle Database software stack. Use the SHOW CONFIGURATION BystandersFollowRoleChange command to see the value of this property. first recording that a fast-start failover cannot happen. This walkthrough uses Maximum Availability mode to achieve "zero data loss". Databases that have been disabled after a role transition are not removed from the broker configuration, but they are no longer managed by the broker. However, there may be exceptions to the recommendation to choose a physical standby database as the target standby database. Before stopping an observer, note the following: The observer does not stop immediately when you issue the STOP OBSERVER command. Reinstate or re-create standby databases in the configuration that were disabled by the broker. It automatically recovers the maximum amount of redo data for the protection mode the configuration is operating in. If the FastStartFailoverPmyShutdown configuration property is set to TRUE, then the former primary database will have been automatically shut down and must be manually restarted before the master observer can attempt to reinstate it. Add the primary database and each standby database to the address list. This file contains connect identifiers to both the primary and the target standby databases. For example: Scenario 6: Enabling Fast-Start Failover and Starting the Observer. So if the original Primary database is still accessible, you should always consider a switchover first. If no name is specified for the observer then a default observer name, the host name of machine where the START OBSERVER command is issued, is used. primary, only the observers specified in the property can be use in the SET this script is run before the fast-start failover is initiated. One is the master FastStartFailoverLagLimit configuration property is set to zero) or When you configure data guard using OCI console, the default mode is set to maxprotection. 1. 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). This allows Data Guard to remain functional during maintenance periods when the application listeners are down. For more information, see START OBSERVER IN BACKGROUND. 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). You can start the observer before or after you enable Note: Data Guard requires dedicated server connections for proper operation. Oracle Data Guard work on two database roles Primary and Standby. Whereas a switchover to a logical standby database will invalidate and disable all of the physical and snapshot standby databases in the configuration. disable fast-start failover with the FORCE option on the In this mode, the FastStartFailoverLagLimit configuration property is set to a non-zero value. In maximum performance mode, the ability to automatically failover is restored A far-sync instance cannot be used in maximum protection mode. 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. An observer is an OCI Each observer has its own log file. Oracle Data Guard can switch a standby database to the primary role in case a production database becomes unavailable due to . An immediate failover is the fastest type of failover. The configuration status returns the SUCCESS status after the observer reestablishes its connection to the primary database, which then notifies the target standby database. After a failover, a bystander will not automatically become the new failover target. isolated. environment variable is set and the specified directory has the To start an immediate failover, use the DGMGRL FAILOVER TO database-name IMMEDIATE command. We'll start with switchovers. See Enabling Fast-Start Failover for more information.

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