The advanced way is in the following article: Connect-Time Failover by a Dynamic Service Name. In Oracle RAC configurations, the Inaccessible Logfile and Stuck Archiver health conditions may only be applicable to a single instance. In 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. This section will help you get started with creating a wrapper script to automatically start and restart the FSFO observer. The target standby database when it does not have connectivity with the primary database, fast-start failover is disabled only on the target standby database. 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. This walkthrough assumes that all ORLs and SRLs on the primary and standby databases are the same size. ZERO DATA LOSS: Fast-start failover is enabled with zero data loss. To verify the readiness of the fast-start failover configuration, issue the DGMGRL SHOW CONFIGURATION VERBOSE command or the SHOW FAST_START FAILOVER command on the primary database. As described in theFlashback Database section, Flashback Database takes place in two stages: a restore stage and a media recovery stage. Add the wallet location and override to sqlnet.ora. The primary and target standby must have connectivity for the STOP OBSERVER command to complete successfully. See START OBSERVER IN BACKGROUND for more information If there is another standby database that is available for failover, you can perform a manual failover to that standby database after you first disable fast-start failover using the FORCE option on that standby database. It has two parts in the following order: Configuration declaration this section is mandatory. ORACLE instance shut down. 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. Post failover, there are two methods of rebuilding your failed primary Method 1: Rebuild from scratch -> RMAN duplicate Method 2: Flashback database -> only if Flashback was enabled Reinstate failed primary: When you use data guard broker, with just one command, the primary can be rebuilt. Restart the database to the mounted state, Use Cloud Control or DGMGRL to reinstate the database. After fast-start failover is enabled and up to four observers are started, one observer is nominated as the master observer that continuously monitors the environment to ensure the primary database is available. The walkthrough begins with a single database that will become the primary of a Data Guard configuration. If client-side ONS configuration is used, the client-side ONS configuration file must specify the hostname and port of the ONS daemon(s) of the primary database and each standby database. Apply services on all other bystander standby databases automatically begin applying redo data received from the new primary database. After a failover, a bystander will not automatically become the new failover target. Note that the new primary database does not need to be restarted. Unlike the primary / standby interconnect, where bandwidth and latency are determining performance factors, the observer requires very little network bandwidth and is not overly latency sensitive, allowing the it to be placed practically anywhere a reliable connection is available. Create a unique connect alias for each database. database (if real-time query is enabled). 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. lower detection times for primary database failures, you must Starts redo transport services to begin transmitting redo data to all bystander standby databases that were not disabled. More specifically, we can have an asynchronous second read-only Managed instance in the same or in a different region. Issue the DISABLE FAST_START FAILOVER command or the DISABLE FAST_START FAILOVER FORCE command. In the media recovery phase, Flashback Database applies redo to bring the database up to the standby_became_primary_scn. Installing and starting an observer is an integral part of using fast-start failover and is described in detail in the following sections: Oracle Data Guard Installation explains that you can either install only the Oracle Client Administrator or you can install the complete Oracle Database Enterprise Edition or Personal Edition on the observer system. When the observer loses its connection to the primary database for a period of time greater than that specified by the FastStartFailoverThreshold property, it attempts a failover to the standby database. START OBSERVING [cfg_group_name] starts a new observer for each broker configuration in the specified group. Select name,open_mode,database_role from v$database; Step:2 Cancel the MRP process As mentioned above, Maximum Availability mode is mandatory for Oracle Database 10g and optional for Oracle Database 11g. Log into the new primary and verify that the changes made it across. You cannot perform a manual failover to the target standby database for the same reason. This allows Data Guard to remain functional during maintenance periods when the application listeners are down. The broker automatically reenables the database as part of reinstating it. To override this behavior and allow a fast-start failover to occur if the observer is unable to contact the primary for more than FastStartFailoverThreshold seconds, set the ObserverOverride property to TRUE. The word manual is used to contrast this type of failover with a fast-start failover (described in Fast-Start Failover). Before enabling fast-start failover, use one of the following techniques same permissions. milliseconds and that of ObserverRetryCount is 10. /home1/dataguard/config_NorthSales/callout/fsfocallout.ora. With FSFO enabled, Broker expects to find an observer, which we haven't started yet, so if you verify the at this point with 'show configuration', Broker will report a warning (if it doesn't, give it a minute to discover that the observer isn't there). This action may result in two databases in the configuration simultaneously assuming the primary database role should fast-start failover occur. See the START OBSERVER command for more information. A broker configuration can belong to multiple groups. For example, to determine if fast-start failover can occur, the FS_FAILOVER_STATUS column displays either SYNCHRONIZED or TARGET UNDER LAG LIMIT and the FS_FAILOVER_OBSERVER_PRESENT column displays YES for the target standby database. The new standby database is a viable target of a failover when it begins receiving redo data received from the new primary database. enabling fast-start failover. This allows for redundancy in your Data Guard observer setup as well. ASYNC. You must set both The "Configuring Authentication" chapter of the Oracle Database Security Guide provides detailed instructions for creating a wallet. Note: If you have just enabled archivelog mode, force an archive log creation ( alter system archive log current) to ensure that at least one archive log exists. Running a StatusReport on the primary should verify that the error is due to a missing observer. If you already have an FRA, you may need to increase its size in order to accommodate the Flashback Database files. (Note: 11.1.0.7 adds the StaticConnectIdentifier Broker database property to allow you to specify a different service name.) observer, whether it is currently connected to the primary and target standby databases, Bystander standby databases can be shut down at any time in any order without impacting fast-start failover. performance protection mode with fast-start failover. Its primary job is to perform a failover when conditions permit it to do so without violating the data durability constraints set by the DBA. While Oracle 11g's Data Guard definitely protects a database when the entire production site is lost via its failover capabilities, it's still necessary for an Oracle DBA to intervene to complete the failover process. 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. Default value is 10 miliseconds. Default value is 100 configuration named ConfigurationSimpleName. 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. 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. This can be done regardless of whether the failover was done to a physical, logical, or snapshot standby database. Write Engineering Change Proposal documentation and reports to request permission to install, replace . database is managed by Oracle Clusterware, broker directs Oracle Clusterware to Suppose you have a primary database, BOSTON, and a standby database, CHICAGO. This page will not allow you to alter the protection mode. It is then started and stopped on the primary database. For each observer, the V$FS_FAILOVER_OBSERVERS view provides the Enable Fast-Start Failover Using Cloud Control. Database dismounted. The former primary database is disabled. The group of broker configurations to be managed is declared in the observer configuration file. The foundation of FSFO is Data Guard - a primary and at least one standby. In such cases, the failed primary database is reinstated as a physical standby database. This file distance. Oracle Database PL/SQL Packages and Types Reference for more information about the DBMS_DG package. For any work, queries and help. Some properties have changed between those releases. Thus, the validity of the values of these properties is not verified until after the switchover. The broker never automatically reinstates the former primary database if a fast-start failover was initiated because a user configuration condition was detected or was requested by an application calling the DBMS_DG.INITIATE_FS_FAILOVER function. They cannot be reinstated. stored in the specified path using the default file names. For Oracle RAC databases, see Oracle Real Application Clusters Administration and Deployment Guide for more information about configuring database services with the SRVCTL utility. As shown in the table, fast-start failover can be enabled in maximum availability After the conversion, the broker will start Redo Apply to apply accumulated redo data, before failing the database over to the primary role. If fast-start failover is enabled, then a switchover can be performed only to the pre-specified target standby database and only if the standby database is synchronized with the primary database or is within the configured lag limit, for the max availability and max performance modes respectively. orapwd file=$ORACLE_HOME/dbs/orapw$ORACLE_SID. This is a good time to enable FSFO to make sure that all of the prerequisites have been met. MASTEROBSERHOST TO command. Use synonyms for the keyword you typed, for example, try "application" instead of "software.". You must re-create the database manually from a copy of the current primary database and then reenable the database in the broker configuration. Manual failover to the fast-start failover target can be performed without receiving an acknowledgement from the observer. Note: this state also occurs on the primary during startup when fast-start failover is possible and neither the target standby database nor the observer are present to confirm it is okay to continue opening the database. The broker continuously monitors for all sessions that are connected Note: Data Guard requires dedicated server connections for proper operation. These are the actions the broker performs after you start a switchover. A manual failover is already in progress. Reinstatement of the failed primary database as a new standby database failed. The new ConfigurationWideServiceName configuration property can be used to simplify setting up this connect identifier. In previous releases, OCI and ODP.NET clients receive FAN notifications via Oracle Advanced Queuing (AQ). 1. Oracle Data Guard Broker is a utility that can help you manage your Oracle Data Guard. Use the EMCLI verb dg_configure_observers. contains important information about the observer. 1. The observer is very lightweight, requiring few system resources. You must provide a connect identifier, through which one or more databases in a specific broker configuration can be reached. 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. Oracle Database 10g allows a different password file to be used as long as the SYS passwords are the same on the primary and standby. to set the time taken to detect a failure on the primary database: Set the FastStartFailoverThreshold SQL>select sequence#, applied from v$archived_log; 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 syntax for the optional definition of a broker configuration group is: The group definition section is optional. The v$database view has has columns specifically for monitoring FSFO status. The target standby database is synchronized with the primary database if it is a configuration operating in maximum availability or maximum protection mode, or the target standby database is within the lag limit if it is a configuration operating in maximum performance mode. Oracle also provides Fast Application Notification (FAN) for OCI clients and Fast Connect Failover for JDBC clients. flashback logs on that database. 2. crash, data in this file can be used to restart the observer to the issue commands and interact with the broker configuration. Specifying Preferred Observers Based on Current Primary. Set both these properties to achieve a primary failure detection time of 1 So if the original Primary database is still accessible, you should always consider a switchover first. add service command. To run an observer as a background process, use the DGMGRL command START OBSERVER IN BACKGROUND. However, if the standby has had contact from the primary within the period of time specified by the FastStartFailoverThreshold property, the standby prevents the failover attempt. In a Data Guard environment primary database is open in read write mode and the standby database in read only mode for reporting purpose. Time for action - using interfaces to monitor Data Guard; Other replication solutions and Data Guard; Transitions the target standby database into the primary database role, as follows: Changes the role of the database from standby to primary. 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. The following sections describe these topics: Prerequisites for Enabling Fast-Start Failover, Viewing Fast-Start Failover Configuration Statistics and Status, Performance Considerations for Fast-Start Failover, Reinstating the Former Primary Database in the Broker Configuration, Shutting Down Databases In a Fast-Start Failover Environment. 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. services. It is very much useful, when the organization has multiple standby sites. environment variable must have exclusive permissions wherein it can be accessed only Displays if the standby database's redo applied point lags 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. You can use Cloud Control or DGMGRL, to perform either a complete (recommended) or an immediate failover. What is true about data guard set up with fast-start failover (FSFO) in Oracle Cloud Infrastructure (OCI)? This property allows you to specify a priority ordered The terminal session will appear to hang at this point. configuration file exists. Tags: Data Guard, Oracle. Configure the protection mode. How to Re-create and Reenable a Disabled Database. Subsequent changes to the same block during the same snapshot are not recorded. file (fsfo.dat). Verify there are no active users connected to the databases. db1_a: Alias to connect to the dynamic Data Guard service on database "a", db1_b: Alias to connect to the dynamic Data Guard service on database "b", db1_a_static: Alias to connect to the static Data Guard service on database "a", db1_b_static: Alias to connect to the static Data Guard service on database "b". under the $DG_ADMIN directory. Click Disable in the Fast-Start Failover wizard. However, no additional data is applied on the standby database once you invoke the failover. During failover, bystanders "follow" the primary by default, flashing back and reapplying redo from the new primary as necessary. SHOW OBSERVER command to confirm that the switch took place. Problems with automatic reinstatement are frequently due to misconfiguration, so let's look at this in a bit more detail. ConfigurationSimpleName is created. times that the observer retries a failed ping before it initiates a That is, if the observer is connected to any instance in the Oracle RAC, all instances will show a value of YES. The remaining Data Guard-related parameters will be set by Broker later in the walkthrough. miliseconds. All standbys other than the failover target are considered bystanders (v$database.fs_failover_status = 'BYSTANDER'). primary. If these parameters are modified outside of Broker, it raises a warning. When the conditions for fast-start failover are met, the Broker adds messages to the observer log and broker log indicating that fast-start failover would have been initiated. Issue the following commands on Primary database and Standby database to find out: If an application has called this function and it has received a status of SUCCESS, then the master observer attempts a fast-start failover. It's good practice to use separate listeners for application connections and Data Guard connections. Then set the configuration protection mode to maximum availability. For this reason, you should first issue this command on the target standby database. Examples of starting observers using DGMGRL are included in Scenario 6: Enabling Fast-Start Failover and Starting the Observer. Data Guard. through these services to exit or for the specified wait time Refer to the appropriate Oracle RAC or Oracle Restart documentation for further information. Using the db_unique_name of each database as the Oracle Net alias is simple and intuitive. 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. The configuration and database status report that the observer is not running and return one of the following status messages: While the configuration is in the unobserved state, fast-start failover cannot happen. Oracle Data Guard configuration with DGMGRL. You can create two callout configuration scripts, a Issue the following SRVCTL commands so that both databases in the Data Guard configuration know about the two potential services for each database: To start things up initially, you must manually start the services on the right node. File. Note that primary and standby databases must be licensed for Oracle RAC or Oracle Active Data Guard in order to use Application Continuity. 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. We'll leave the other properties at their default values for the walkthrough, but you should become familiar with all of the Broker config and database properties. The Flashing back a database is much faster and more seamless (one simple DDL statement) than traditional point-in-time or SCN-based recovery. It is also supported for fast-start failover to physical standbys in maximum availability data protection mode. 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. committing because a fast-start failover may have occurred while it was There is no need to multiplex SRLs in order to protect redo as with ORLs (the redo is already protected in the ORLs of the primary). restart the new physical standby database. 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. An immediate failover is the fastest type of failover. the primary database that failed or took longer than the time Flashback Database records the before-image of changed blocks. 5. To stop the observer when fast-start failover is disabled, the primary database must be running. This can be avoided by first disabling fast-start failover with the FORCE option on the target standby. list of the observers that can become the master observer when that FSFO can also be used with logical standbys and an FSFO-enabled configuration may have multiple standbys with a mix of physical and logical, but only one standby can be the failover target at any given time. 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. Overview of Switchover and Failover in a Broker Environment. It's secondary job is to automatically reinstate a failed primary as a standby if that feature is enabled (the default). This section describes how to configure an Oracle Net connect descriptor that meets this requirement. Immediately after issuing command in step 2, shut down and restart the standby instance STAN: If no value is specified for the Use the oraenv script provided by Oracle. Before beginning a failover, first determine that there is no possibility of recovering the primary database in a timely manner, and ensure that the primary database is shut down. may allow the primary database to continue redo generation after Overall commit latency is increased by the round-trip network latency. The name of the callout configuration file is fsfocallout.ora. Conditions shown in blue are enabled by default. It is not reversible. If you intend to switch back to the original primary database relatively soon, you may allow the physical and snapshot standbys to remain disabled. By default, the broker always determines whether bystander standby databases will be viable standby databases for the new primary when performing a complete failover. To maintain a viable disaster-recovery solution in the event of another disaster, you may need to perform additional steps. LinkedIn:https://www.linkedin.com/in/hari-prasath-aa65bb19/ Once the observer is started, you cannot change the file's name and location. command is submitted successfully, the command-line prompt on the See Setting the Protection Mode for Your Configuration. Reenabling Disabled Databases After a Role Change describes how to do this. POTENTIAL DATA LOSS: Fast-start failover is enabled with some data loss. database. Download Ebook Oracle 11g 12c Data Guard With Asm Lab Practice A Complete Hands On Lab Practice To Manage A Data Guard . 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. Step 4: Enable Fast-Start Failover Now we are ready to enable FSFO: DGMGRL> enable fast_start failover; Enabled in Zero Data Loss Mode. Displays when the primary and target standby databases are synchronized and the configuration is operating in maximum availability mode. Displays only on a logical standby database that has not yet completed loading a copy of the primary database's data dictionary. 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. observer immediately begins monitoring the status and connections to 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. Setting it to 'FALSE' leaves the database open and stalled until it is terminated or signaled to proceed in the event a failover did not take place (e.g. When running the START 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. Sets up redo transport from the new primary to the other members of the configuration, Starts Redo Apply services on the new standby, Ensures the other standbys in the broker configuration are viable to the new primary, Integrates with Oracle Clusterware and Oracle Global Data Services (GDS) to ensure that the proper services are started after a role change. For information about enabling fast-start failover, see Enabling Fast-Start Failover. . Unless action is taken to change the failover target to one of the bystanders, the new primary will be without a failover target until the former primary is reinstated as a standby. Note that a switchover operation may be started before the specified wait See the Oracle Reference and Data Guard Administrator guides for your release for details. It is also possible to initiate failover using the dgmgrl failover command. This property specifies the amount of data, in seconds, that the target standby database can lag behind the primary database in terms of redo applied. FAN events are always published through ONS. Use Cloud Control or DGMGRL to perform either a complete (recommended) or an immediate failover. file, observer runtime data file (fsfo.dat), fast-start failover callout directory. This is cleared on both when the reinstatement has been completed. The database on which the procedure is called notifies the observer. 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. Don't initiate failover unless at least 30 minutes of history is available. Contains the observer runtime data file for the broker It uses the connect identifier specified in the observer configuration file to locate the credentials for a broker configuration from the Oracle wallet. Data Guard Configuration Details:-. 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. must ping the primary database. If the group name is not provided, then a new observer is started for each broker configuration defined in observer.ora. Create a pre-callout script, or a post-callout script, or both.
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