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. After step 1 finishes, Switch the original physical standby db STAN to primary role; In maximum protection mode, an automatic failover is always possible because the 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. 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. redo generation on the primary database will be stalled. For example: Fast-start failover occurs if both the observer and the target standby database lose connection to the primary database for the period of time specified by the FastStartFailoverThreshold configuration property. 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. Many customers use Oracle Database deployed on Amazon Elastic Compute Cloud (Amazon EC2) to run their Oracle E-Business Suite applications. 8.2 Private Cloud Appliance and . All other registered observers are considered to be backup observers. After the patch has been successfully applied to all databases, take the following steps to enable fast-start failover and start the observer. When this command is issued, the actual In case of primary database failure, you will need to perform failover to transition the standby database to the primary role. isolated. If this operation is successful, a zero data loss failover may be possible even if the primary database is not in a zero data loss protection mode. The default value is ALL. The reinstated database acts as the fast-start failover target for the new primary database, making a subsequent fast-start failover possible. For example, if the old standby was a physical or snapshot standby, then the old primary must be re-created as a physical standby. The ObserverOverride and ObserverReconnect properties allow you additional control over the connection to the primary. /home1/dataguard/config_NorthSales/callout/fsfocallout.ora. In this case, only observers on ob1-host and Note: Data Guard requires dedicated server connections for proper operation. This is called failover. Verify the configuration from both hosts. Depending on the failover and the types of standby databases involved, some of the databases may need to be reinstated or re-created. If the new primary database was a primary database in the past, and had block (See Disabling Fast-Start Failover for important considerations when using the FORCE option.). To do this, use the SET ObserverConfigFile and SHOW ObserverConfigFile commands. In Oracle RAC configurations, the Inaccessible Logfile and Stuck Archiver health conditions may only be applicable to a single instance. PRIM>SHUTDOWN IMMEDIATE; 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. To help you select an appropriate switchover or failover target, use the following DGMGRL commands which perform checks on the database to determine its readiness to complete a role change. Switchover to a logical standby database is disallowed when the configuration is operating in maximum protection mode. There is no data loss during a switch-over. 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). command for more information about starting the The broker may not be able to disable fast-start failover on all databases in the broker configuration when you issue the DISABLE FAST_START FAILOVER FORCE command. failover to the target standby database. Remember to check Flashback Database history before aborting the primary. This means that in order for a flashback database operation to succeed, observer and the standby both lose contact with the primary. You can specify particular conditions for which a fast-start failover should occur using either Cloud Control or the DGMGRL ENABLE FAST_START FAILOVER CONDITION and DISABLE FAST_START FAILOVER CONDITION commands. This article - the seventh in this ongoing . OBSERVE-ONLY: Fast-start failover is enabled in observe-only mode. Group definition this section is optional. Disable fast-start failover using the DGMGRL DISABLE FAST_START FAILOVER command. If automatic reinstatement fails, the broker will log errors and the former primary database will remain in the mounted state. In this example, there are 3 ORLs with a max group# of 3. 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. ORACLE instance shut down. Bystander standby databases can be shut down at any time in any order without impacting fast-start failover. 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. The minimum detection time is 6 seconds, which is the default This 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. For information about enabling fast-start failover, see Enabling Fast-Start Failover. required permissions, DGMGRL reports an error. 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. Broker is a Data Guard management utility that maintains state information about a primary and its standby databases. A switchover guarantees no data loss and is typically done for planned maintenance of the primary system. If the database is managed by Oracle Clusterware, broker does not open any of the If you re-create the old primary database, it must be created as the standby type of the old standby database. 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. Connect to the target standby database and issue the FAILOVER command to perform a failover, specifying the name of the standby database that you want to become the primary database: Specify the optional IMMEDIATE clause to perform an immediate failover if any of the following conditions are true: An ORA-752 error has occurred at the standby database, An ORA-600 [3020] error has occurred at the standby database and Oracle support has determined that it was caused by a lost write at the primary database. During failover, bystanders "follow" the primary by default, flashing back and reapplying redo from the new primary as necessary. The services required on the primary database are: Log Writer Process (LGWR) - Collects redo information and updates the online redo logs. Both Cloud Control and the DGMGRL CLI will do this automatically as part of failover. The observer's main purpose is to enhance high availability and lights out computing by reducing the human intervention required by the manual failover process that can add minutes or hours to downtime. We'll start it interactively for now to verify that everything's working. 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. 2. 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. It is important that all SRVCTL add service options be identical on all the databases so that the services behave the same way before and after a role change. But it will also continue trying to reconnect to the primary database indefinitely. command does not have a network connection to the primary database. In a DataGuard environment when the Primary instance fails you need to go through the Failover and Reinstate processes in order to restore the database service, as described in the documentation: Changes a standby database to the primary role in response to a primary database failure. Do this prior to every failover test. Data Guard broker does not manage or store credentials. This is because the -role qualifier is taken into account only by Data Guard broker, and at database startup. SET MASTEROBSERVER TO allows you to manually change the observer configuration file. 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. This section describes how to configure an Oracle Net connect descriptor that meets this requirement. SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE FINISH; Table 6-3 FS_FAILOVER_OBSERVER_PRESENT Column of the V$DATABASE View, The master observer is currently connected to the local database, The master observer is not connected to the local database. 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. Otherwise, the DUPLICATE TARGET DATABASE command will fail with "RMAN-20208: UNTIL CHANGE is before RESETLOGS change". See the START OBSERVER observer is still in contact with the standby. If errors occur during the disable operation, the broker returns an error message and stops the disable operation. on ob3-host and ob4-host will not It is actually a low-footprint OCI client built into the DGMGRL CLI (Data Guard Broker Command Line Interface) and, like any other client, may be run on a different hardware platform than the database servers. Create a trigger based on the, Oracle Database PL/SQL Language Reference, Choosing a Target Standby Database for Switchover, Choosing a Target Standby Database for Failover, Scenario 9: Performing a Switchover Operation, Scenario 10: Performing a Manual Failover Operation, Database Service Configuration Requirements, Troubleshooting Problems During a Switchover Operation, How the Broker Performs a Complete Failover Operation, How the Broker Performs an Immediate Failover Operation, Setting the Protection Mode for Your Configuration, Scenario 7: Enabling Fast-Start Failover When a Far Sync Instance Is In Use, Description of "Figure 6-1 Relationship of Primary and Standby Databases and the Observer", Enabling Fast-Start Failover Task 7: Configure Actions Before and After Fast-start Failover (Optional), Directing a Fast-Start Failover From an Application, Fast-start Failover Callout Configuration Files, Oracle Data Guard Command-Line Interface Reference, Description of "Figure 6-2 The Observer in the Fast-Start Failover Environment", Oracle Enterprise Manager Command Line Interface. Reenabling Disabled Databases After a Role Change describes how to do this. Use Recovery Manager (RMAN) to back up the PeopleSoft database on a regular backup schedule. When you execute commands that affect multiple observers, if you have not specified a name and location for the observer configuration file, then broker searches the current working directory for a file named observer.ora. If there are no registered observers when fast-start failover is enabled, then the first observer started is designated as the master observer, and all others started later are backup observers. If the service has been configured to start automatically (-policy AUTOMATIC), then the service will automatically start only after a database role change. Role Transitions: Switchover and Failover 1 -7 Oracle Data Guard Broker Framework 1 -9 C hoosing an Interface for Administering a Data Guard Configuration 1 -10 Oracle Data Guard: Architecture (Overview) 1 -11 Primary Database Processes 1 -12 . 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. It has two parts in the following order: Configuration declaration this section is mandatory. connection, or the database on which you issued the disable fast-start failover 1. Contains the observer log file for the broker configuration named Create a unique connect alias for each database. An observer can be moved from one computer to another through a process of stopping it on one system and and re-starting it on another. 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). In maximum availability mode, set the LogXptMode database property for both the primary and target standby databases to SYNC or FASTSYNC. 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. If there is only one standby database in the configuration, you can skip this step and continue with Task 3. Flashback Database stores its logs in the Flash Recovery Area (FRA), so the FRA must be large enough to store at least 60 minutes of Flashback Database history. Make sure that xdpyinfo exist under PATH variable. VALIDATE 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. You cannot perform a manual failover to the target standby database for the same reason. SUSPENDED is cleared when connectivity with the primary database is restored. Once the observer has initiated a fast-start failover, the primary database shuts down automatically. A good method to determine Flashback Database storage requirements is to enable Flashback Database and observe the amount of storage it uses during several peak loads.
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