Once the primary database regains connectivity with the target standby database, fast-start failover will be disabled for all the databases in the configuration. Verify the standby database instance is mounted. To do this, use the SET ObserverConfigFile and SHOW ObserverConfigFile commands. fsfocallout.ora and they have the required permissions. 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. Updates the broker configuration file to record the change in roles. Problems with automatic reinstatement are frequently due to misconfiguration, so let's look at this in a bit more detail. You might, for instance, use this to allow the observer to monitor the databases using the same connect identifiers as the client applications. The drain_timeout is specified in the SRVCTL PRIM>SHUTDOWN IMMEDIATE; been enabled on the database prior to the failover and there must be sufficient The connect descriptor must contain the SERVICE_NAME parameter in either case. Reinstatement is supported only after failover in a broker configuration. Default value is 10 miliseconds. In an immediate failover, it is also possible to failover to a standby database (terminal standby) that gets redo from another standby database (cascader). For switchovers, understanding all of the factors can simplify the choice of which standby database to consider as your new primary database. The standby database must be re-created or reinstated before it can serve as a standby for the new primary database. Set the ObserverPingInterval and name of the observer log file is 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. 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. The master observer waits the number of seconds specified by the FastStartFailoverThreshold configuration property before attempting a fast-start failover when the primary database has crashed or has lost connectivity with the observer, as in the following situations: The primary database loses its connections with both the observer and target standby database. ERROR: Unable to verify the graphical display setup. Broker Configuration Has Only One Registered Observer. Oracle Data Guard work on two database roles Primary and Standby. 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. The terminal session will appear to hang at this point. value is 10. fsfo_postcallout are stored in the same location as configuration property. See Oracle Data Guard Concepts and Administration for information about tuning the log apply rate for a physical standby database. OBSERVER command, if this directory does not have the If the observer is unable to regain a connection to the primary database within the specified time, and the target standby database is ready for fast-start failover, then fast-start failover ensues. It is also supported for fast-start failover to physical standbys in maximum availability data protection mode. During failover, bystanders "follow" the primary by default, flashing back and reapplying redo from the new primary as necessary. After setting local_listener, register the database with the listener and verify the services have been registered. An observer is an OCI You must use the Oracle wallet to store the credentials for all broker configurations to be managed. See Sources of Diagnostic Information for details about the broker's drc* log files. You can switch over or manual failover to a bystander database. The string "NONAME" cannot be used as an observer name. The word ALL cannot be used as a group name because it is a reserved keyword. If errors occur during the disable operation, the broker returns an error message and stops the disable operation. Learn how your comment data is processed. The new primary database is opened in read/write mode and redo transport services are started. A switchover guarantees no data loss and is typically done for planned maintenance of the primary system. Sign in to Azure only. In such a case, no attempt is made to transmit any unsent redo from the cascader to the terminal standby. This guide uses the naming convention of appending an underscore followed by a letter to the db_name to create the db_unique_name. Instead, when broker notifies the Oracle To determine if the configuration is ready for fast-start failover to occur, issue the DGMGRL SHOW DATABASE command, or query the V$DATABASE view on either the primary or target standby databases. 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. physical standby database. ORACLE instance shut down. 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. A fast-start failover to the target standby database fails. For information about event notification and database connection failover support for global services, see the Oracle Database Global Data Services Concepts and Administration Guide. These facilities allow applications written to take advantage of them to receive asynchronous notification of database events, including role transitions. 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. created when the START OBSERVER command is issued. Data Guard. We will create 4 SRLs starting with group# 11. Before enabling fast-start failover, use one of the following techniques 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. 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. 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. If both the observer and designated standby database lose connectivity with the primary database for longer than the number of seconds specified by the FastStartFailoverThreshold configuration property, the observer will initiate a fast-start failover to the standby database. What is true about data guard set up with fast-start failover (FSFO) in Oracle Cloud Infrastructure (OCI)? POTENTIAL DATA LOSS: Fast-start failover is enabled with some data loss. Neither the primary database nor the logical standby database needs to be restarted after the switchover completes. 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. Switch-over steps: Step-A: Shutdown primary database: SQL> shut immediate; Database closed. Flashback Database is a continuous data protection (CDP) solution integrated with the Oracle Database. Bystander standby databases may be disabled by the broker during the failover, and they must be reinstated or re-created before they can serve as standby databases to the new primary database. For more information, see START OBSERVER IN BACKGROUND. time specified by maximum configured The command SHOW OBSERVER provides detailed information about registered observers. To prevent automatic reinstatement of the former primary database in these cases, set this configuration property to FALSE. 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. Use the wrapper script to start the observer process when the observer host boots or to restart it if it dies. Verify Before Switch-over: For this reason, you should first issue this command on the target standby database. environment that is guaranteed to either lose no data (when the Click Disable in the Fast-Start Failover wizard. Note that the FastStartFailoverThreshold property can be changed even when fast-start failover is enabled. Overall Steps:-. A snapshot standby cannot be the target of a switchover or fast-start failover operation. files include the observer configuration file (observer.ora), observer log If the broker performs a switchover or failover, then it starts the service SALESRW or SALESRO based on the current role of the database. In Oracle Database 11g, the password file on the standby must be a physical copy of the password file on the primary due to security enhancements introduced in Oracle Database 11g. Fast-start failover is enabled, but this standby database is not the target of the fast-start failover. The default name for Verify dmon process is running and broker parameters viz. The observe-only mode for fast-start failover enables you to test how fast-start failover will work in your environment. Observers should be installed and run on a computer system that is separate from the primary and standby systems. In this case, the primary database stalls and prevents any further transactions from To achieve Another good test is to simulate network failures that leave the primary up, but isolated from the failover target standby and the observer. Keep this trigger as simple and reliable as possible, limiting it to only what is absolutely necessary at the moment of role transition, since any failures at this point may affect availability. 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. You can customize fast-start failover setup for a specific application by using the DBMS_DG PL/SQL package. Other members of the configuration will receive redo from the designated redo source based on the new primary. alter database set standby database to maximize availability; If you don't already have a standby database, use your favorite method to create one. Reinstatement of the failed primary database as a new standby database failed. If the switchover occurs to a physical standby database, and the former primary 1. The primary database can be opened even if there is no acknowledgement from the observer or target standby. The original primary database will be restarted as a part of the switchover operation. Careful consideration should be given before enabling fast-start failover for either of these conditions because doing so will supersede availability options provided by Oracle Clusterware. Make sure the last redo data transmitted from the Primary database was applied on the standby database. At this point, you can either: Disable fast-start failover (described in Disabling Fast-Start Failover) and attempt to open the former primary database, Manually reinstate the former primary database, as described in Reenabling Disabled Databases After a Role Change. The observer configuration file is a text file and the syntax to define observers and groups is similar to that used in the listener.ora or tnsnames.ora files. failure on the primary database. 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. You can start, stop, and show observers for a group of configurations. On Linux/Unix, the directory specified by the DG_ADMIN environment Suppose you have a primary database, BOSTON, and a standby database, CHICAGO. You can find detailed information about all observers, including master observers and backup observers, in the V$FS_FAILOVER_OBSERVERS view. Please contact us at contactus@smarttechways.com. primary database. It automatically recovers the maximum amount of redo data for the protection mode the configuration is operating in. In the event of a This exercises the configuration, but triggers failover differently than losing contact with the primary. Input commands are shown in shaded boxes in normal text. Apply services on all other bystander standby databases automatically begin applying redo data received from the new primary database. When enabling fast-start failover, the broker verifies that the property indicates an existing standby. 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. Oracle Data Guard can switch a standby database to the primary role in case a production database becomes unavailable due to . 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. 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. 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. Although the default value of 30 seconds is typically adequate for detecting outages and failures on most configurations, you can adjust failover sensitivity with this property to decrease the probability of false failovers in a temporarily unstable environment. To enable fast-start failover in Cloud Control, use the Fast-Start Failover wizard. The broker continuously monitors for all sessions that are connected The ObserverReconnect configuration property specifies how often the observer establishes a new connection to the primary database. The primary database can be reinstated if it had flashback database enabled. 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. Databases that can be reinstated will have the following status value: For the REINSTATE command to succeed, Flashback Database must have Log into the new primary and verify that the changes made it across. Oracle Data Guard Command-Line Interface Reference for more information about these broker commands. If the FastStartFailoverPmyShutdown configuration property is set to TRUE, the primary database will shut down after FastStartFailoverThreshold seconds has elapsed if redo generation has been stalled and the primary database is unable to reestablish connectivity with either the observer or target standby database. Starting with 11 is purely cosmetic - it allows new ORL groups to be added later while keeping their group# in the same sequence as the existing ORLs. 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. 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 For Maximum Availability environments, change this to synchronous. Time for action - using interfaces to monitor Data Guard; Other replication solutions and Data Guard; Group definition this section is optional. fast-start failover operation, the observer checks if a fast-start failover When restarting the databases, you may restart them in any order. configuration named ConfigurationSimpleName. What is true about Data Guard setup with fast-start failover? The default value is 30 seconds. 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. 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). Do not use Shared Server (formerly MTS) for Data Guard. For each observer, the V$FS_FAILOVER_OBSERVERS view provides the The broker first converts the original primary database to run in the standby role. file, observer runtime data file (fsfo.dat), fast-start failover callout Have a means of notifying someone if standby apply falls too far behind. To start an immediate failover, use the DGMGRL FAILOVER TO database-name IMMEDIATE command. Once the Oracle instance is transitioned into primary database status in either switchover or failover, the life of the database as the standby ends and its service as the primary database . Logical standby databases that are disabled during failover can be reinstated. Note that enabling FSFO does not make the configuration ready for automatic failover - that requires an observer, which we'll get to next. You cannot create the standby DB system in a different AD from the primary DB system.