If fast-start failover is initiated, the master observer verifies the target standby database is ready to fail over to the primary database role. Another consequence of immediate failover is that all other databases in the configuration are disabled and must be reinstated or re-created before they can serve as standby databases for the new primary database. Execute the following on primary database NORTH: Execute the following on the physical standby database SOUTH: If the broker now performs a switchover or failover, it automatically starts the SALES service on the correct database, based on the database's role. Most of the network services used in a FSFO environment may use dynamic registration, but to enable Broker to restart instances during role transitions or during reinstatement after a failover, you must define a static service named db_unique_name_dgmgrl. Step:6 A failover may or may not result in data loss depending on the protection mode in effect at the time of the failover. See the "DISABLE FAST_START FAILOVER" command in Oracle Data Guard Command-Line Interface Reference for more information. This may take a few minutes. It has two parts in the following order: Configuration declaration this section is mandatory. See Prerequisites for more information. 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. Therefore, the target standby never falls behind the primary During a switchover, the primary database transitions to a standby role, and the standby database transitions to the primary role. The total storage requirement is proportional to the number of distinct blocks changed during snapshots - e.g. In fact, failovers are so reliable, fast, and simple that switchovers become the exception rather than the rule. If the group name is not provided, then a new observer is started for each broker configuration defined in observer.ora. Running a StatusReport on the primary should verify that the error is due to a missing observer. This list describes restrictions when fast-start failover is enabled. FastStartFailoverAutoReinstate is set to FALSE, Another failover or switchover occurred after the fast-start failover completed but before the former primary database restarted, The master observer cannot connect to the former primary database, The former primary database cannot connect to the new primary database, The former primary database and the new primary database are not configured in the same fast-start failover environment, The former primary database was disabled because of a manual failover when fast-start failover was disabled. It is not reversible. Fast-start failover can incur data-loss within the time specified by FastStartFailoverlagLimit. By default, a fast-start failover is done when both the observer and the standby cannot reach the primary after the configured time threshold (FastStartFailoverThreshold) has passed. The v$database view has has columns specifically for monitoring FSFO status. observer and the others are backup observers. Step:5Bounce your database and verify database name its open mode and its role. 11.2 rac servicefailover - Use the FastStartFailoverTarget configuration property on the current primary database to specify one or more fast-start failover targets. Reenabling Disabled Databases After a Role Change describes how to do this. If the target standby database is a snapshot standby database, all of its instances must be restarted to the mount mode before performing failover. If provided, then each group needs to have at least one broker configuration declared in the second part. 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. How To Configure Client Failover For Data Guard Connections - Oracle Fast-start failover quickly and reliably fails over the target standby database to the primary database role, without requiring you to perform any manual steps to invoke the failover. STAN is now transitioned to the primary database role.Now your PHYSICAL STANDBY Database has become PRIMARY. This file is stored in the If there is only one observer, then it is considered to be the master observer. Thus, the validity of the values of these properties is not verified until after the switchover. When you are experiencing network disconnections and you issue the DISABLE FAST_START FAILOVER FORCE command on the primary database or a standby database that does not have connectivity with the primary database, fast-start failover may not be disabled for all databases in the broker configuration. Then, on the Fast-Start Failover Change Mode page, click Enabled. These tasks assume that you are connected as SYS or SYSDG and that a primary and standby database are already set up in a broker configuration. Fast-Start Failover in Oracle 11g Data Guard. Cloud Control will start the observer. For example: The following example shows the fast-start failover information for the DRSolution configuration: The following SHOW OBSERVER command displays information about multiple observers in the DRSolution broker configuration. For example: Using DGMGRL, you can do this by examining the output of the SHOW CONFIGURATION LAG. FastStartFailoverLagLimit property. A fast-start failover to the target standby database fails. Note that if failover was performed on a snapshot standby database, the old primary must be either reinstated or re-created as a physical standby database. file, observer runtime data file (fsfo.dat), fast-start failover callout The name of the callout configuration file is fsfocallout.ora. A switchover to a physical standby database is preferable because all databases in the configuration will be available as standby databases to the new primary database after the switchover operation completes. 12c Dataguard, In The FS_FAILOVER_STATUS column in the V$DATABASE view for the target standby database displays a reason why fast-start failover cannot occur. 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. DGConnectIdentifier, "Scenario 9: Performing a Switchover Operation" for an example of using the VALIDATE DATABASE command to show a database's readiness to complete a role switchover, "Scenario 10: Performing a Manual Failover Operation" for an example of using the VALIDATE DATABASE command to show a database's readiness to complete a role failover. (It is permissible to change the RedoRoutes property on all standby databases including target standby databases. After a failover, the original primary database can no longer participate in the Data Guard configuration. When restarting the databases, you may restart them in any order. Any database that was disabled while multiple role changes were performed cannot be reinstated. environment variable must have exclusive permissions wherein it can be accessed only For this build, we will use a single physical standby database. We'll start it interactively for now to verify that everything's working. After the former primary database has been repaired, the observer reestablishes its connection to that database and reinstates it as a new standby database. 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. There are many examples, and Ritesh Chhajer offers this example of doing a Data Guard switchover using dgmgrl: 1. lower detection times for primary database failures, you must not already enabled, the observer waits until fast-start failover Problems with automatic reinstatement are frequently due to misconfiguration, so let's look at this in a bit more detail. There's a big difference between a system that's FSFO enabled and one that's FSFO ready. variable must have read, write, and execute permissions for the directory owner this script is run before the fast-start failover is initiated. Setting this property to 'TRUE' (the default) causes the primary to self-terminate. Disable fast-start failover using the DGMGRL DISABLE FAST_START FAILOVER command. STANDBY> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY; the current working directory. Instead, it allows an observer that is monitoring the configuration to initiate a fast-start failover should database conditions warrant a failover. 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. have received all the redo data the primary has generated in order for automatic failover to November 20, 2009. Note that a switchover operation may be started before the specified wait To start an observer, you must be able to log in to DGMGRL with an account that has database (if real-time query is enabled). In the media recovery phase, Flashback Database applies redo to bring the database up to the standby_became_primary_scn. A switchover is a role reversal between the primary database and one of its standby databases. Broker will validate the configuration, set parameters on both databases, and start managed recovery. The following example displays the contents of the fast-start failover This includes the following: broker configuration is in UNSYNC or LAGGING state or unobserved state, failover target is invalid, reinstatement is in progress, or a master observer switch is in progress. If there is more than one standby database in the configuration, you must explicitly set the FastStartFailoverTarget property on the primary database to name one or more candidate target standby databases. 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. The broker first converts the original primary database to run in the standby role. property. The values that indicate FSFO is ready for failover are listed below. under the $DG_ADMIN directory. environment that is guaranteed to either lose no data (when the This is true regardless of the settings for the FastStartFailoverPmyShutdown and FastStartFailoverAutoReinstate configuration properties. present, you must start the observer manually using the following Use the wrapper script to start the observer process when the observer host boots or to restart it if it dies. The connect descriptor must contain the SERVICE_NAME parameter in either case. If the database is managed by Oracle Clusterware, broker does not open any of the This may result in data loss. 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. Create a script to automate FSFO failover initiation and use it as your standard method for standby flips. If necessary, you can shut down the primary or target standby database in a fast-start failover environment. For Maximum Availability environments, change this to synchronous. 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. Switching over to a logical standby database results in the snapshot and physical standby databases in the broker configuration being disabled by the broker, making these databases no longer viable as standby databases. In order to fully automate switchover, Broker needs SYSDBA credentials in order to restart one or both databases. The NetTimeout property specifies the number of seconds LGWR will block waiting for acknowledgment from the standby in synchronous mode before considering the connection lost (corresponds to the NET_TIMEOUT option of log_archive_dest_n). To move the observer to another computer: There is no need to disable fast-start failover when you move the observer. time, if all the sessions that are connected though the active services Since a fast-start failover (automatic failover) could become a false failover when the observer or the standby database cannot connect to the primary database within a specific time, which may cost the database to lose some transactions followed by reinstating or recreating the standby database (the former primary database). Any unsent redo data residing on the far sync instance is transmitted to the target physical standby prior to converting the physical standby into a primary database. If both of those observers are unavailable, the observers If the switchover occurs to a physical standby database, and the former primary 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. Dataguard switchover and failover steps in Oracle Note that the new primary database does not need to be restarted. If failover is not possible for some reason, then the master observer will continue checking whether the standby database is ready to fail over. observers for a single Data Guard configuration. (Yes, bystanders need Flashback Database too). are configured correctly. A switchover guarantees no data loss and is typically done for planned maintenance of the primary system. DNS CNAME) that always resolves to the primary. Choose a value high enough to avoid false disconnects from intermittent network trouble. Written by authors well-known for their talent with RAC, Pro Oracle Database 11g RAC on Linux . file (fsfo.dat). The guide attempts to be operating system agnostic; however, some examples may contain platform specific elements such as path and file naming conventions. Simply use DISABLE FAST_START FAILOVER. That is, if the observer is connected to any instance in the Oracle RAC, all instances will show a value of YES. For reliable startup, the initial connection should always be made to the primary. 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. How we create a failover group in Azure Managed Instance After FSFO is enabled, Broker will continue to check that Flashback Database is enabled during health checks. 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. property. Except for testing purposes, it is not recommended that you start more than one observer on the same host for a Data Guard broker configuration. However, there may be situations in which you must disable fast-start failover when 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. Be aware that if you issue the following manual commands on either of those databases, then both the SALESRO and SALESRW services would be started on the databases regardless of what you may have earlier specified with the SRVCTL -role qualifier. stored in the specified path using the default file names. Create a wallet and set the default username and password to the database's SYSDBA credentials (usually SYS). 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. You can also query the V$FS_FAILOVER_STATS view to display statistics about fast-start failover occurring on the system. Database services can be configured to be active in specific database roles on Oracle RAC databases and on single-instance databases managed by Oracle Restart.
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