The walkthrough begins with a single database that will become the primary of a Data Guard configuration. The failed primary database requires reinstatement as a new standby database to the new primary. This method will disable fast-start failover on all databases in the broker configuration. the location of the observer log file, and the location of the observer runtime data $DG_ADMIN directory. In a Managed Instance with multiple databases in Azure we can have high availability. Oracle recommends that this property be set to a value that is small enough to allow timely detection of faults at the primary database, but large enough to limit the overhead associated with periodic observer connections to an acceptable level. Another good test is to simulate network failures that leave the primary up, but isolated from the failover target standby and the observer. The real test of the configuration is a successful role transition in both directions with both switchover and FSFO failover. SHOW OBSERVERS [FOR fg_group_name ] shows information about observers for all configurations in the specified group. configuration named ConfigurationSimpleName. To maximize the benefits of FSFO, the observer should run on a different host than the primary and standby databases. The price for this guarantee is increased commit latency ( log file sync waits). Facebook:https://www.facebook.com/HariPrasathdba Create a unique connect alias for each database. As a result the observer may still initiate fast-start failover to the target standby database, if conditions warrant a failover. When fast-start failover is disabled, no observer is called the master observer; all observers have the same functionality. (It is permissible to change the RedoRoutes property on all standby databases including target standby databases. When both databases have been restarted, you may restart the observer. Create a wallet and set the default username and password to the database's SYSDBA credentials (usually SYS). 1. After the fast-start failover completes successfully, the master observer will attempt to reinstate the former primary database as a new standby database when a connection to the former primary database is reestablished, and the FastStartFailoverAutoReinstate configuration property is set to TRUE. You can register up to four observers to monitor a single Data Guard broker configuration. The syntax for the optional definition of a broker configuration group is: The group definition section is optional. Figure 6-2 The Observer in the Fast-Start Failover Environment. Application Continuity is supported for Oracle Data Guard switchovers to physical standby databases. environment variable to specify the default location for client-side broker files. Use Broker's "show configuration" command to determine FSFO status and the "show database statusreport" command to drill down for details if Broker reports a problem. The following table summarizes which standby types are supported in which protection modes when fast-start failover is enabled. Input commands are shown in shaded boxes in normal text. Switchover and Failover Operations - Oracle Help Center JAVA applications can use FAN programmatically by using the JDBC FAN application programming interface to subscribe to FAN events and to execute event handling actions upon the receipt of an event. For Oracle Database Release 12.2 and higher, Oracle Enterprise Manager Cloud Control (Cloud Control) supports configuring multiple observers using the Enterprise Manager Command Line Interface (EM CLI). If the new primary database was a primary database in the past, and had block If fast-start failover is Note the following points about the observe-only mode: The primary database can enter UNSYNC or LAGGING state without an acknowledgement from the observer or target standby. 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. Determines whether or not any standby databases that did not participate in the failover operation have applied redo data beyond the new primary database, and thus need to be disabled. The broker verifies the state and status of the databases to ensure that the switchover transitioned the databases to their new role correctly. FSFO can provide substantial gains in high availability and disaster recovery preparedness for all environments, from inexpensive Cloud-based systems to global distributed data centers. We'll start it interactively for now to verify that everything's working. This file Media Recovery - Once the restore is complete, recovery proceeds as a typical media recovery, applying redo from archived and online redologs and rolling back uncommitted changes with undo. database is managed by Oracle Clusterware, broker directs Oracle Clusterware to Any apply delay must be removed before beginning a switchover. configuration. Duplicate configuration names in configuration definitions are not allowed. More specifically, we can have an asynchronous second read-only Managed instance in the same or in a different region. Make sure the last redo data transmitted from the Primary database was applied on the standby database. 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. For example: Scenario 6: Enabling Fast-Start Failover and Starting the Observer. However, if you want the observer to reconnect to the primary database periodically as a means of testing the health of the network connection to the primary, then use the ObserverReconnect configuration property. If you like a connect-time failover to survive across a data guard switchover, you need another way to do it. 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. You will then need to re-create the physical standby databases from a copy of the new primary database before you can reenable them. 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. value is 10. This may take a few minutes. The standby VM (myVM2) has the Oracle software installed only. Then set the configuration protection mode to maximum availability. 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. In an Oracle Data Guard configuration, the SRVCTL -startoption for a standby database is always set to OPEN after a switchover. Manual failover can be performed even if the pre-condition checks are not met. 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. Stopping the observer does not disable fast-start failover. This post will demonstrate the procedure to test Oracle Data Guard Fast-Start Failover by shutting down the server where the primary database is running from. You can switch back to the original primary and then either retry the switchover to the original target standby, or choose another standby in the configuration to switch over to. Change the failover target to the standby being switched over to, Change the failover target to the desired standby. STAN is now transitioned to the primary database role.Now your PHYSICAL STANDBY Database has become PRIMARY. Automatic failover for Autonomous Data Guard enabled Autonomous If a single-instance primary database (either Oracle RAC or non-Oracle RAC), or if all instances of an Oracle RAC primary database are shut down with the ABORT option, the observer attempts a fast-start failover. It automatically recovers the maximum amount of redo data for the protection mode the configuration is operating in. For manual failover, the observer is started and communicating with the target standby database. Neither the primary database nor the logical standby database needs to be restarted after the switchover completes. STANDBY>connect /@STAN as sysdba To stop it, you can do either of the following: Choose the Stop Observer option on the first page of the fast-start failover wizard and click Continue at the bottom of the page. Immediately after issuing command in step 2, shut down and restart the standby instance STAN: 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 configuration status returns the SUCCESS status after the observer reestablishes its connection to the primary database, which then notifies the target standby database. This is a good time to enable FSFO to make sure that all of the prerequisites have been met. Additionally, the new master observer is identified in the output shown for the SHOW FAST_START FAILOVER and SHOW OBSERVER commands. Displays when the target standby database does not have all of the primary database redo data and the configuration is operating in maximum availability mode. ob2-host can be a master observer when The Column Value in the following table is consistent across instances in an Oracle Real Applications Clusters (Oracle RAC) environment. For information about event notification and database connection failover support for global services, see the Oracle Database Global Data Services Concepts and Administration Guide. OBSERVER command, if this directory does not have the Create a trigger on this event to perform actions specific to your environment after a switchover or failover, such as updating the name resolution service to point to the new primary. The playground: You can also reinstate bystander standby databases that were disabled during a failover operation. All other registered observers are considered to be backup observers. operation. receives redo data from a far sync instance. The targets are referred to as candidate targets. For example: The default value for the FastStartFailoverThreshold property is 30 seconds and the lowest possible value is 6 seconds. This section describes how to configure and verify each prerequisite. To do this, use the SET ObserverConfigFile and SHOW ObserverConfigFile commands. Only the observer can initiate FSFO failover. To use a far sync instance with fast-start failover, the far sync instance transport mode must be set to either SYNC or FASTSYNC and the target standby database transport mode must be set to ASYNC. It automatically sets Data Guard related database initialization parameters on instance start and role transitions, starts apply services for standbys, and automates many of the administrative tasks associated with maintaining a Data Guard configuration. In an immediate failover, it is also possible to failover to a standby database (terminal standby) that gets redo from another standby database (cascader). See Manual Failover for complete information about manual failovers. Fast-Start Failover in Oracle 11g Data Guard - Database Journal You must re-create the database manually from a copy of the current primary database and then reenable the database in the broker configuration. Check the spelling of your keyword search. Writing the wrapper itself and the means to determine when to execute it are up to you. For this build, we will use a single physical standby database. To specify which observer can be a master observer when a database is in With a value of TRUE for this property, the primary will shut down after being stalled for the number of seconds specified by the FastStartFailoverThreshold property. Goal. The command fails if the file does not exist. Metadata for the fuzzy snapshot is stored in the flashback log itself. (as it might in maximum availability and maximum performance modes). 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. Reinstatement is supported only after failover in a broker configuration. Each database in a Data Guard configuration must have a unique name. In order to maintain separation of Broker and non-Broker activity, a second static service is recommended. standby database is mounted, broker remembers this setting. 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. These are some points to consider before you begin a switchover. If you want to capture any logging generated by the observer, use the LOGFILE IS option on the START OBSERVER command, and ensure that the file name is unique. SET MASTEROBSERVER TO allows you to manually change the observer configuration file. 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 SRVCTL utility does not automatically take the database role into account, so any time you start a service manually, you must specify the name(s) of the service you want started. The Appendix provides information oncreating a simple wrapper script to start the observer as a background process. 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. A switchover guarantees no data loss and is typically done for planned maintenance of the primary system. session. How to Enable Fast-Start Failover in Oracle Data Guard 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. Issue the following command while connected to any database in the broker configuration, except the database that is to be reinstated: The newly reinstated standby database will begin serving as a standby database to the new primary database.