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. Flashing back a database occurs in two stages: For FSFO environments, set db_flashback_retention_target = 60 or higher to provide sufficient Flashback Database history for automatic standby reinstatement. The service is then configured to be active in the PRIMARY role on the standby database SOUTH, so that it will be active on that database after a role transition. Verify the primary database instance is open. 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. With increased latency comes decreased throughput; however, in some cases the difference in throughput may be made up by increasing parallelism. In this case, no attempt is made to transmit any unsent redo from the far sync instance to the target physical standby prior to converting the physical standby into a primary database. After a switchover completes, the broker preserves the overall Oracle Data Guard protection mode as part of the switchover process by keeping the protection mode at the same protection level (maximum protection, maximum availability, or maximum performance) it was at before the switchover. By default, both files are stored in $ORACLE_HOME/dbs. Such preparation includes: Ensuring that standby redo log files are configured on the primary database. Note: the FSFO observer version must match the database version. It shuts down or stalls because it is likely a failover has occurred. Restart the database to the mounted state, Use Cloud Control or DGMGRL to reinstate the database. If you intend to switch back to the original primary database relatively soon, you may allow the physical and snapshot standbys to remain disabled. Provides an automatic failover environment Alternatively, use the RedoRoutes property to configure the redo transport mode for the target standby and the database currently in the primary role. If you are more concerned about the performance of the primary database than a minimal loss of data, consider enabling fast-start failover when the configuration protection mode is set to maximum performance. 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. Fast-start failover will not occur unless all instances comprising the Oracle RAC primary database are perceived to have failed. In this case, the primary database stalls and prevents any further transactions from You can customize fast-start failover setup for a specific application by using the DBMS_DG PL/SQL package. directory has the same permissions as its parent directory. cannot use a different name for this file. Overall commit latency is increased by the round-trip network latency. To run an observer as a background process, use the DGMGRL command START OBSERVER IN BACKGROUND. If the primary or target standby databases lose connections to all backup observers, then the broker does not try to nominate a backup observer as the new master observer, and the broker reports that the configuration is not observed. observer and the others are backup observers. fast-start failover when: A network outage isolates the primary database from the observer and the target standby database before conditions exist that warrant a failover. REINSTATE REQUIRED is present only after fast-start failover has occurred and shows on both the new primary database and the database undergoing reinstatement. Oracle recommends that this property be set to a value that is small enough to allow timely detection of faults at the primary database, but large enough to limit the overhead associated with periodic observer connections to an acceptable level. DG BrokerDG BrokerData Guard BrokerOracleDGRMAN Duplicate . 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. After Create a unique connect alias for each database. A switchover guarantees no data loss and is typically done for planned maintenance of the primary system. The string "NONAME" cannot be used as an observer name. If this is an Oracle RAC physical standby database managed by Oracle Clusterware, then the broker directs Oracle Clusterware to restart the new standby database. Only the master observer can coordinate fast-start failover with Data Guard broker. the primary and target standby databases. SQL>SHUTDOWN IMMEDIATE; An observer is a separate OCI client-side component that run on a different computer from the primary and standby databases and monitors the availability of the primary database. Regards, Narottam Tagged: dataguard dba rac Welcome! lower detection times for primary database failures, you must Note: You can also use TNS aliases defined in the tnsnames.ora file when setting the local_listener parameter. FAN events are published using Oracle Notification Services (ONS) for all Oracle integrated database clients in Oracle Database 12c and later. Failover:- In case of worst situation with data guard primary database, or not available for production than we can activated standby database as a primary production database. DGMGRL can be used to manage multiple observers in a group of broker configurations. 3. Oracle Data Guard Command-Line Interface Reference for more information about these broker commands. When this command is issued, the actual Verify the configuration from both hosts. 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. The reduced need for manual intervention can increase availability without increasing management costs. fast-start failover succeeds, if a post-callout script is specified in the fast-start Any database that was disabled while multiple role changes were performed cannot be reinstated. Some properties have changed between those releases. Fast-start failover enables the Data Guard broker to rapidly and automatically failover to a previously chosen standby database without requiring manual intervention. 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. mode when the fast-start failover target is a logical or physical standby database that If the observer is stopped abnormally (for example, by typing CTRL/C), restart it and reference the existing fsfo.dat file with the FILE IS qualifier. Oracle Data Guard configuration with DGMGRL. This section describes how to stay on top of your FSFO environments. If the protection mode was at maximum protection, it is reset to maximum performance. After the patch has been successfully applied to all databases, take the following steps to enable fast-start failover and start the observer. using the same SYS credentials you used when you connected to the 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. You want to prevent fast-start failover from occurring because the primary database will resume service soon. guaranteed to lose no data. times that the observer retries a failed ping before it initiates a The DB_ROLE_CHANGE event will fire whenever a database is opened for the first time after a role transition. These are some points to consider before you begin a switchover. FSFO uses Flashback Database as part of the process of reinstating a failed primary as a standby. Complete Failovers in Configurations Using Far Sync Instances. This action may result in two databases in the configuration simultaneously assuming the primary database role should fast-start failover occur. 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. 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. Data Guard broker does not manage or store credentials. specified by the ObserverPingInterval property. The default group is all the configurations defined in the observer configuration file. Examples of starting observers using DGMGRL are included in Scenario 6: Enabling Fast-Start Failover and Starting the Observer. After setting local_listener, register the database with the listener and verify the services have been registered. So if the original Primary database is still accessible, you should always consider a switchover first. 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. Flashing back a database is much faster and more seamless (one simple DDL statement) than traditional point-in-time or SCN-based recovery. SET ObserverConfigFile used to specify a customized observer configuration file. Just be sure to include a Flashback Database history check in the script to provide an option to abort if a failover would require a manual reinstate. For example: In the following example, assume the network between the primary database and the observer has failed. The broker will not allow a switchover to a standby that has an apply delay configured (DelayMins property is set to a non-zero value). Fast-Start Failover allows Data Guard to automatically failover to a previously chosen standby database without requiring manual intervention to invoke the failover. The remaining Data Guard-related parameters will be set by Broker later in the walkthrough. 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 guide makes few assumptions about your existing environment and includes examples for creating a physical standby database and Data Guard Broker configuration. An spfile is required to persist these changes. Look for the desired data in the RAM. It is instructive to watch the alert logs on both databases as well as the observer log after aborting the primary to gain insight into what happens during FSFO failover. The broker allows the switchover to proceed as long as there are no errors for the primary database and the standby database that you selected to participate in the switchover operation. The following is an example of setting the LogXptMode property: Alternatively, use the RedoRoutes property to set the redo transport mode for the target standby and database that is currently in the primary role. Commands For Managing Observers on Multiple Configurations. The existence of a .suc file, DGMGRL to manage multiple observers on multiple configurations. required permissions, DGMGRL reports an error. exit. the service configuration. Only two databases, the primary and the failover target, can be in the FSFO configuration at any given time. As shown in the table, fast-start failover can be enabled in maximum availability Start the Data Guard listener on both "a" and "b" hosts. Es gratis registrarse y presentar tus propuestas laborales. A switchover is a role reversal between the primary database and one of its standby databases. 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. 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. Once fast-start failover is enabled, the broker will ensure that fast-start failover If errors occur during the disable operation, the broker returns an error message and stops the disable operation. broker does not allow the primary database to commit transactions until it has regained The act of switching roles should be a well-planned activity. Once the observer has initiated a fast-start failover, the primary database shuts down automatically. 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. If only a path is specified, the files are File. If the Broker configuration is changed to make a bystander the new failover target (probably a good idea if the failed database will be down for a while), the observer will not automatically reinstate the former primary because it is no longer part of the FSFO configuration. For more details about managing Redo Apply services using properties, see Managing Log Apply Services. Reinstate the original primary database to act as a standby database in the new configuration. Fast-start failover allows the broker to automatically fail over to a previously chosen standby database in the event of loss of the primary database. 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. Unlike ORLs, SRLs should be created with only one member per group. For Maximum Availability environments, change this to synchronous. The subdirectories that DGMGRL creates under this directory will also have the This is a good time to enable FSFO to make sure that all of the prerequisites have been met. There are prerequisites that must be met before the broker allows you to enable fast-start failover. Initiate the switchover on the primary database PRIM: In this case, Flashback Database cannot be used to reinstate databases. Rather, fast-start failover will be enabled in accordance with the current protection mode. If a bystander standby database is not disabled by the broker during this failover, it will remain in the state it was in before the failover. maximum availability and maximum performance modes, to avoid a It wouldn't be much of a test if we didn't verify that our durability constraints were being met, so let's make a change on the primary and see if it survives the failover. The default name of the observer runtime data file is primary database must have network connectivity. The observer configuration file is a text file and the syntax to define observers and groups is similar to that used in the listener.ora or tnsnames.ora files. When you configure data guard using OCI console, the default mode is set to maxprotection. This document only talks about switchover involving physical standby 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. So SALESRW will start on CHICAGO (which is now the primary) and SALESRO will start on BOSTON (which is now the physical standby). By default, the broker always determines whether bystander standby databases will be viable standby databases for the new primary when performing a complete failover. Change the failover target to the standby being switched over to, Change the failover target to the desired standby. The syntax for the configuration declaration is: The definition for each broker configuration is: The configuration-name can be different from the name defined in the metadata of the Data Guard Broker configuration. configuration property. Verify there are no active users connected to the databases. committing because a fast-start failover may have occurred while it was See the Cloud Control online help for more information. For a system to process an instruction involving data access, these are the certain steps involved: Fetch the block of data from the hard disk (secondary/permanent storage) to the primary memory (e.g. SHOW CONFIGURATION VERBOSE, or SHOW OBSERVER When the standby becomes available again, the primary and standby re-synchronize and resume synchronous redo transfer. Reinstatement of the failed primary database as a new standby database failed. To failover, connect to the standby database and use the DGMGRL FAILOVER TO db-unique-name command. The steps in this section describe the tasks involved to perform a manual failover. if the observer is not running, The master observer and the target standby database are inconsistent with regard to the current state of the broker configuration, If the protection mode is maximum availability or maximum protection and the target standby database was not synchronized with the primary database at the time the primary database failed, If the protection mode is maximum performance and the apply point of the target standby database lags the redo generation point of the primary database by more than the amount specified by the FastStartFailoverLagLimit configuration property at the time the primary database failed. If the observer is unable to regain a connection to the primary database within the specified time, then the observer begins a fast-start failover provided the standby database is ready to fail over. Before a directory does not have the required permissions, broker does the following: When you run DGMGRL commands, if a path and file name are explicitly specified for
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