See the "DISABLE FAST_START FAILOVER" command in Oracle Data Guard Command-Line Interface Reference for more information. This method will disable fast-start failover on all databases in the broker configuration. If the protection mode was at maximum availability or maximum performance, it remains unchanged. 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. If the database is managed by Oracle Clusterware, broker does not open any of the You cannot perform a manual failover to the target standby database for the same reason. The default group is all the configurations defined in the observer configuration file. Add the primary database and each standby database to the address list. 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. The remaining Data Guard-related parameters will be set by Broker later in the walkthrough. Dataguard switchover and failover steps in Oracle Refer to the appropriate Oracle RAC or Oracle Restart documentation for further information. (Yes, bystanders need Flashback Database too). Click Failover. Simply use DISABLE FAST_START FAILOVER. database (if real-time query is enabled). What is true about data guard set up with fast-start failover (FSFO) in Oracle Cloud Infrastructure (OCI)? The minimum value of ObserverPingInterval is 100 It uses the connect identifier specified in the observer configuration file to locate the credentials for a broker configuration from the Oracle wallet. SQL> Select Database_role from v$Database; A Senior Engineer's Guide to the System Design Interview 8.2 Private Cloud Appliance and . on particular instances based on the service configuration. Failovers become routine. To allow the master observer to automatically reinstate the former primary database, the database must be started and mounted. Steps to Create a Physical Standby Databa se 3 -3 Preparing the Primary Database 3 -4 FORCE LOGGING . Reinstatement of the failed primary database as a new standby database failed. observer on ob1-host will be given priority over They must be re-created from a copy of the new primary database. STAN is now transitioned to the primary database role.Now your PHYSICAL STANDBY Database has become PRIMARY. If the switchover transitions a logical standby database to the primary role, then: The original primary database will be switched to a logical standby role. After a failover, the original primary database can no longer participate in the Data Guard configuration. multiple, inexpensive servers is the basis for the failover and other fault-tolerance features that RAC provides. 3. Fast-start failover is inhibited in this case. SQL> Select Database_role from v$Database; The broker first converts the original primary database to run in the standby role. The default name of the callout configuration file is fsfo_postcallout are stored in the same location as In this case, the FS_FAILOVER_STATUS and FS_FAILOVER_OBSERVER_PRESENT columns will appear as shown in the following table and fast-start failover will not occur: Oracle Database Reference for more information about the V$DATABASE view. time specified by maximum configured $DG_ADMIN/config_ConfigurationSimpleName/callout After FSFO is enabled, Broker will continue to check that Flashback Database is enabled during health checks. After you click the Reinstate button, Cloud Control begins reinstating the database. PDF Oracle Database 19c: Data Guard Administration Workshop Examples of starting observers using DGMGRL are included in Scenario 6: Enabling Fast-Start Failover and Starting the Observer. If they are isolated from each other, then you must first disable fast-start failover by using the FORCE option, and then stop the observer. (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. 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. Indexing is a mechanism by which the underlying data is mapped for faster retrieval. Use the SQL ALTER DATABASE MOVE DATAFILE command to rename or relocate an online data file on a physical standby that is a fast-start failover target if the standby is mounted, but not open. This file contains connect identifiers to both the primary and the target standby databases. In addition, some standby databases may be disabled by the broker during the failover if the broker detects that they have applied redo beyond where the new primary database had applied. The same thing happens if a shutdown and startup of either database occurs - the service that is started is the one that matches the role of the database being started. For example, if all your physical standbys are also unavailable, then failing over to a logical standby is your only choice. Testing FSFO failover requires simulating loss of the primary. Table 6-1 Content of Default Directory for Client-side Files, Contains the observer configuration file that is used by Manual failover gives you control over exactly when a failover occurs and to which target standby database. the current working directory, Uses standard output for displaying the observer logs. You can, however, perform a manual failover to a snapshot standby. The terminal session will appear to hang at this point. This section describes how to configure and verify each prerequisite. It will return PHYSICAL STANDBY, Other members of the configuration will receive redo from the designated redo source based on the new primary. So if the original Primary database is still accessible, you should always consider a switchover first. How To Setup Dataguard Broker Configuration (DG Broker) In 19c When a fast-start failover occurs because either a user configurable fast-start failover condition is detected or an application initiates a fast-start failover by calling the DBMS_DG.INITIATE_FS_FAILOVER function, the former primary database is always shut down and never automatically reinstated. Standby databases not involved in the switchover (known as bystander standby databases) continue operating in the state they were in before the switchover occurred and will automatically begin applying redo data received from the new primary database. Instead, it allows an observer that is monitoring the configuration to initiate a fast-start failover should database conditions warrant a failover. SHOW ObserverConfigFile used to check the runtime property ObserverConfigFile. If the specified log file is not accessible, or the LOGFILE IS option is not used, then the observer output is sent to standard output. Once Flashback Database has succeeded, the observer will convert the database to a standby, bounce it, and begin apply services. If the former physical standby database was running with real-time query enabled, the new physical standby database will run with real-time query enabled. However, re-enabling Flashback Database will require a bounce since the database must be mounted and not open. same permissions. 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. only. file also declares broker configurations and defines configuration In cases where We'll start with switchovers. 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". 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. callout configuration file. 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. See Prerequisites for more information. ObserverPingRetry properties before Stopping the observer does not disable fast-start failover. There's a big difference between a system that's FSFO enabled and one that's FSFO ready. If a group name is not specified, then SHOW OBSERVERS alone is also a valid command. If Flashback Database fails, automatic reinstatement stops and you will have to perform a manual SCN-based recovery to the standby_became_primary_scn and complete the reinstatement. If you intend to switch back to the original primary database relatively soon, you may allow the physical and snapshot standbys to remain disabled. services. To perform specified actions before or after a fast-start failover PDF Download Solutions Oracle Data Guard 11gr2 Administration Beginner S Guide If fast-start failover is enabled you can still perform a switchover or a manual failover as long as certain conditions are met. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. configuration file, such as START OBSERVING, In this case, the observer cannot perform a fast-start failover even if conditions warrant a failover. Use broker configuration properties to set the time taken to detect a US Coast Guard Auxiliary. If the new primary database was a primary database in the past, and had block PDBs. Figure 6-2 shows the observer monitoring a fast-start failover configuration. Subdirectories within instructions for the DGMGRL command-line interface. 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. There are configuration requirements that must be met in order to publish and properly handle FAN events generated as the result of a broker-managed failover. In Maximum Availability mode, FSFO guarantees that no transaction that has received a commit acknowledgment will be lost during a failover. Reinstate the original primary database to act as a standby database in the new configuration. 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. 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. Implement Oracle Data Guard on an Azure Linux virtual machine 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. The reduced need for manual intervention can increase availability without increasing management costs. Facebook:https://www.facebook.com/HariPrasathdba To maintain a viable disaster-recovery solution in the event of another disaster, you may need to perform additional steps. What is true about data guard set up with fast-start failover (FSFO) in Oracle Cloud Infrastructure (OCI)? MASTEROBSERVERHOSTS, DGMGRL reports an error if the This can be avoided by first disabling fast-start failover with the FORCE option on the target standby. You can start, stop, and show observers for a group of configurations. Cancel MRP process. Duplicate configuration names in configuration definitions are not allowed. When a switchover is started, the primary and standby databases that are involved should have as small a redo lag as possible. This will signal the observer to initiate failover after the FSFO threshold timeout has been reached (default is 30 seconds). 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. To enable fast-start failover, both the primary and target standby databases must be running and have connectivity, and satisfy all of the prerequisite conditions listed in Prerequisites for Enabling Fast-Start Failover. Writing the wrapper itself and the means to determine when to execute it are up to you. If a non-zero value is specified for the 1. 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. 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. A failover to a physical standby database is preferable because 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. This can be done regardless of whether the failover was done to a physical, logical, or snapshot standby database. Group definition this section is optional. During a switchover, the primary database transitions to a standby role, and the standby database transitions to the primary role. When you configure data guard using OCI console, the default mode is set to maxprotection. The default name for Data Guard | Oracle 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. ObserverConfigFile is a DGMGRL session runtime property. In Oracle RAC configurations, the Inaccessible Logfile and Stuck Archiver health conditions may only be applicable to a single instance. time, if all the sessions that are connected though the active services See Manual Failover for complete information about manual failovers. ConfigurationSimpleName. Enable Active Data Guard for read-only workloads. 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. The guide makes few assumptions about your existing environment and includes examples for creating a physical standby database and Data Guard Broker configuration. The application needs to catch this error and respond accordingly. See the START OBSERVER This allows the appropriate Data Guard services, such as redo transport or redo apply, to be started when the database is restarted later for any reason. When using Maximum Availability mode, consider lowering this to reduce the time commits block when the standby becomes unavailable. observer_hostname.log. 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. The simple tests described in this guide are fine for making sure the basics are working, but you'll probably want to develop a more comprehensive set of tests suited to your environment and requirements. For Fast Connection Failover (FCF) to occur, a client must be able to locate the new primary database after a failover. The broker interacts with Oracle Clusterware or Oracle Restart to ensure that the appropriate database services are active and that the appropriate FAN events are published after a role change. As described in theFlashback Database section, Flashback Database takes place in two stages: a restore stage and a media recovery stage. connection, or the database on which you issued the disable 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. Thus, the validity of the values of these properties is not verified until after the switchover. The existence of a .suc file, Starting with 10.2.0.4 (including all versions of 11g and later), Oracle provides the FastStartFailoverPmyShutdown Broker property that allows you to specify what the primary should do if it is still in a stalled state when the FSFO threshold timeout has elapsed.
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