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Oracle Database 11g FSFO adds support for Maximum Performance mode (async redo transfer), providing the flexibility to trade durability for performance. Overall commit latency is increased by the round-trip network latency. Valid values are >= 100. VALIDATE In disaster situations where a failover is necessary, you may be more limited as to which standby database is the best one to pick up the failed primary database's activities. Figure 6-2 The Observer in the Fast-Start Failover Environment. In an environment where there are multiple observers configured, stopping the master observer is not allowed unless it is the last running observer. 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. 2. The word manual is used to contrast this type of failover with a fast-start failover (described in Fast-Start Failover). At a minimum, you must set db_unique_name. 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. The failover was to a logical standby database. In order to apply redo data to the standby database as soon as it is received, use Real-time apply. To allow the master observer to automatically reinstate the former primary database, the database must be started and mounted. The configuration and database status report the same error messages as are returned when there is only one registered observer. file, observer runtime data file (fsfo.dat), fast-start failover callout This is true regardless of the settings for the FastStartFailoverPmyShutdown and FastStartFailoverAutoReinstate configuration properties. observer immediately begins monitoring the status and connections to Displays the current fast-start failover mode. If you want the broker to skip this viability check of bystander standby databases during a complete failover, thus decreasing the overall failover time, set the BystandersFollowRoleChange configuration property to NONE. fast-start failover succeeds, if a post-callout script is specified in the fast-start If any errors occur during either conversion, the broker stops the switchover. The following sections provide information about managing observers: How the Observer Maintains Fast-Start Failover Configuration Information, Patching an Environment When the Observer Is Running and Fast-start Failover Is Enabled. 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. Oracle 11g Physical standby data Guard Failover steps - Data Guard Part The services required on the primary database are: Log Writer Process (LGWR) - Collects redo information and updates the online redo logs. If the Cloud Control agent is installed on the observer Reinstatement will have to be accomplished by other means (manual or scripted Broker commands). A switchover is a role reversal between the primary database and one of its standby databases. Once the primary database regains connectivity with the target standby database, fast-start failover will be disabled for all the databases in the configuration. This guide uses the naming convention of appending an underscore followed by a letter to the db_name to create the db_unique_name. Step 4: Enable Fast-Start Failover Now we are ready to enable FSFO: DGMGRL> enable fast_start failover; Enabled in Zero Data Loss Mode. Provides an automatic failover environment They rely on Oracle Data Guard for high availability databases, with a standby database running in a different availability zone. about starting the observer as a background The name of the callout configuration file is fsfocallout.ora. Therefore, the detection time can be reduced to nearly ObserverConfigFile is a DGMGRL session runtime property. MASTEROBSERVERHOSTS, DGMGRL reports an error if the PDBs. Make sure that your OS environment on the standby is setup. client-side broker files, the specified values are used. the current working directory, Uses standard output for displaying the observer logs. Use the Cloud Control Fast-Start Failover wizard or the DGMGRL ENABLE FAST_START FAILOVER command to enable fast-start failover. groups used by multiple configuration commands. 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). Reinstate the former primary database as a new standby database. Neither the primary database nor the logical standby database needs to be restarted after the switchover completes. 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. Unlike ORLs, SRLs should be created with only one member per group. The minimum detection time is 6 seconds, which is the default If you performed a failover or switchover that requires you to re-create the failed primary database or standby databases that were disabled during the role transition, then follow the procedures in the Oracle Data Guard Concepts and Administration chapter, "Creating a Physical Standby Database" and also the Oracle Data Guard Concepts and Administration chapter, "Creating a Logical Standby Database.". The broker allows the failover to proceed as long as there are no errors for the standby database that you selected to participate in the failover. If a non-zero value is specified for the Now we will see a step-by-step approach to perform a switchover between the primary and the logical standby database: . However, the event notifying a failover is only published for database services that have been configured to be active while the database is in the primary role on the new primary database. Steps for Data guard Switch-over and Switchback in Oracle - Doyensys Oracle Data Guard 11gr2 Administration Beginner S Guide As recognized, adventure as well as experience practically lesson, amusement, . The VALIDATE FAST_START FAILOVER command parses the callout For information about event notification and database connection failover support for global services, see the Oracle Database Global Data Services Concepts and Administration Guide. Verify the configuration from both hosts. The standby can be physical or logical and there can be multiple standbys, but only one of the standbys can be the failover target at any given time. observers for a single Data Guard configuration. Guide to Oracle Data Guard Fast-Start Failover SQL>STARTUP; pre-callout configuration script and post-callout configuration script. When a primary loses contact with both the failover target and the observer simultaneously, it enters a "stalled" state (v$database.fs_failover_status = 'STALLED') and any sessions still connected to the primary will block on commit. Moorestown, New Jersey, United States. The Marketplace image that you use to create the VMs is Oracle:Oracle-Database-Ee:12.1..2:latest. That is, if the observer is connected to any instance in the Oracle RAC, all instances will show a value of YES. 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. When both databases have been restarted, you may restart the observer. /home1/dataguard/config_NorthSales/callout/fsfocallout.ora. The subcommands for this verb include start, stop, setMaster, show, and delete_alternate_observer. Then, on the Fast-Start Failover Configure page, select the standby database that should be the target of a failover. As a result the observer may still initiate fast-start failover to the target standby database, if conditions warrant a failover. redo generation on the primary database will be stalled. The FastStartFailoverTarget configuration property on the primary unless the new property value contains the current fast-start failover target. FSFO enabled configurations having multiple standbys cannot switchover to a standby that is not the failover target. You can also switch the master observer hosts for a group of configurations to one specific host. Choose a value high enough to avoid false disconnects from intermittent network trouble. 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. It will return PHYSICAL STANDBY, 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). In an Oracle Data Guard configuration, the SRVCTL -startoption for a standby database is always set to OPEN after a switchover. The only exception to this is failovers to snapshot standby databases. How to Enable Fast-Start Failover in Oracle Data Guard See the Oracle Maximum Availability Architecture technical briefs at: When setting the FastStartFailoverLagLimit configuration property, consider these tradeoffs between performance and potential data-loss: A low lag limit will minimize data loss but may impact the performance of the primary database. For systems with multiple RAID controllers, consider creating SRLs such that their IO is balanced across the controllers. If there is only one observer, then it is considered to be the master observer. switch does not happen until the next time the primary contacts the target standby, Oracle 19c-Performing Dataguard Switchover Using DGMGRL Utility Currently, this state can be detected only when the database is open. 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. create the directory specified by the DG_ADMIN environment variable and Whether or not standby databases that were not the target of failover (bystander standby databases) are disabled depends upon how much redo data they have applied relative to the failover target and the standby type of the failover target: If the failover target is a physical or snapshot standby database, the original primary database must be reinstated or re-created in order to be a standby database for the new primary database. Determining a Database's Readiness to Change Roles. See Sources of Diagnostic Information for details about the broker's drc* log files. For example, if the old standby was a physical or snapshot standby, then the old primary must be re-created as a physical standby. You want to conduct a manual failover to any standby database in the configuration (for example, because a failure occurred on the primary database at a time when the primary and target standby database were not ready to failover). If the Oracle Data Guard configuration is operating in maximum protection mode, the broker does not allow a switchover to occur to a logical standby database. You can perform a manual failover even if fast-start failover is enabled. You can use this information to identify ahead of time any redo transport configurations that would be incorrect after a role change, including any standbys that will not receive redo because the RedoRoutes property was not configured correctly. To verify the observer is started and the configuration is ready for The primary database was shut down without using the ABORT option. Starting Observers as Background Processes. PRIM>SHUTDOWN IMMEDIATE; alter database recover managed standby database finish; alter database activate standby database; Managed recovery process has been stopped between primary and standby database and standby becomes primary database. In the event of a After FSFO is enabled, Broker will continue to check that Flashback Database is enabled during health checks. The example uses the FROM ACTIVE DATABASE clause introduced in 11g that allows RMAN to create a standby database by copying the primary across the network without the need to store the backup files on disk or tape. However, failover is attempted if the ObserverOverride configuration property is set to TRUE. Once an observer is started, no further user interaction is required. database (if real-time query is enabled). The FS_FAILOVER_OBSERVER_PRESENT column, which indicates whether the observer is running and actively pinging the database. These are the guidelines for choosing a target standby database. primary database. Reference architectures for Oracle databases on Azure - Azure Virtual In a manual failover, you convert a standby database to a primary database because the original primary database failed and there is no possibility of recovering the primary database in a timely manner. 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. ConfigurationSimpleName. Reinstate the original primary database to act as a standby database in the new configuration. (Yes, bystanders need Flashback Database too). See the START OBSERVER During an immediate failover, the broker performs the failover steps described in How the Broker Performs an Immediate Failover Operation. 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. broker opens all the PDBs on the new primary database and on the target standby change tracking enabled, broker enables block change tracking on the new Initiate the failover on the standby database STAN: SQL>connect /@STAN as sysdba SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE FINISH; SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY; 2. If it exists, and it contains a pre-callout script location, created when the START OBSERVER command is issued. Reinstatement restores high availability to the broker configuration so that, in the event of a failure of the new primary database, another fast-start failover can occur. 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. An spfile is required to persist these changes. SET MASTEROBSERVER TO allows you to manually change the observer configuration file. You can find detailed information about all observers, including master observers and backup observers, in the V$FS_FAILOVER_OBSERVERS view. This may result in two databases in the configuration simultaneously assuming the primary database role. file also declares broker configurations and defines configuration They cannot be reinstated. If local_listener is already in use, add the Data Guard listener to the list. This section describes how to stay on top of your FSFO environments. 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. In the previous article, we have seen switching the role of Primary and standby database and failover Primary role to Standby database manually. When fast-start failover is enabled, the broker determines if a failover is necessary and initiates the failover to the current target standby database automatically, with no need for manual intervention. If there is only one standby database in the configuration, you can skip this step and continue with Task 3. The original primary database will be restarted as a part of the switchover operation. 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. In this mode you will need to consider how much data loss is acceptable in terms of seconds and set the FastStartFailoverLagLimit configuration property accordingly. The remaining Data Guard-related parameters will be set by Broker later in the walkthrough. You can register up to four observers to monitor a single Data Guard broker configuration. Use the SHOW CONFIGURATION BystandersFollowRoleChange command to see the value of this property. In this case fast-start failover cannot occur because the databases are not ready to failover. However failing over to a snapshot standby database will require more time because the broker must first convert it back to a physical standby database. observer as a foreground process. This may result in data loss. After the broker receives the STOP OBSERVER request, the request is passed to the observer the next time the observer contacts the broker, and the observer then stops itself. When a switchover is started, the primary and standby databases that are involved should have as small a redo lag as possible. By default, the observer will initiate failover to the target standby if and only if ALL of the following are true: Oracle Database 11g Rel 1 introduced user configurable failover conditions that can trigger the observer to initiate failover immediately. The standby database must be re-created or reinstated before it can serve as a standby for the new primary database. Failover automation ensures a seamless transition from the primary database to a synchronized standby database in cases of failure, while ensuring database availability by replaying uncommitted in-flight transactions. Verify there are no active users connected to the databases. 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. To move the observer to another computer: There is no need to disable fast-start failover when you move the observer. This file database's redo generation point by more than the value specified by the The examples shown in this section do not necessarily show the specific attributes you might need to use in your own environment. MASTEROBSERHOST TO command. The FS_FAILOVER_OBSERVER_PRESENT column displays YES for the target standby database. The lowest possible value is 5 seconds. Write Engineering Change Proposal documentation and reports to request permission to install, replace . To configure fast-start failover in observe-only mode: Fast-start failover will not be triggered if the primary or standby database is shut down normally. maximum availability and maximum performance modes, to avoid a Displays only on a logical standby database that has not yet completed loading a copy of the primary database's data dictionary. To reenable broker management of these databases, you must reinstate or re-create the databases using one of the following procedures: If a database can be reinstated, the database will show the following status: Reinstate the database using the DGMGRL REINSTATE DATABASE command or the reinstate option in Cloud Control, as described in How to Reinstate a Database. add service command. After a failover, a bystander will not automatically become the new failover target. Broker maintains these parameters by issuing ALTER SYSTEM commands as appropriate during role transitions, database startup/shutdown, and other events. We can always fail over to it or have it happen automatically if for some reason the primary Managed Instance has [] The observer is the key element that separates Data Guard failover from its pre-FSFO role as the plan of last resort to its leading role in a robust high availability solution. value is 10. Read-Only Standby and Active Data Guard You can query the V$DATABASE view to verify that the observer is started and the configuration is ready for fast-start failover.