process. Add the primary database and each standby database to the address list. DG_ADMIN environment variable is not set, the files are stored in This is because the -role qualifier is taken into account only by Data Guard broker, and at database startup. The price for this guarantee is increased commit latency ( log file sync waits). Required fields are marked *. 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. SQL> Select Database_role from v$Database; The target standby database has contact with the primary database. Instead, Oracle Clusterware opens PDBs on particular instances based on milliseconds and that of ObserverRetryCount is 10. For instance, you could log into the system running observer1 to stop observer2. This If you will be using RMAN to create the standby database, it also needs a static service to restart the database being created. Switches roles between the primary and standby databases. This is the recommended method for disabling fast-start failover. gets enabled and then begins monitoring. If the client uses remote ONS subscription, the client must specify the hostname and port of the ONS daemon(s) of the primary database and each standby database. Multiplexing SRLs merely adds unnecessary IO and can increase commit latency. On the Data Guard Failover Confirmation page, specify the type of failover that you want to perform: Complete: All available redo is applied on the standby database. Broker stores it configuration information in a mirrored set of files outside the database. Other members of the configuration will receive redo from the designated redo source based on the new primary. When you start a switchover, the broker verifies that at least one standby database, including the primary database that is about to be transitioned to the standby role, is configured to support the overall protection mode (maximum protection, maximum availability, or maximum performance) after the switchover is completed. 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. crash, data in this file can be used to restart the observer to the 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. The mode can have one of the following values: DISABLED: Fast-start failover is disabled. directory by this environment variable does not exist, or the $DG_ADMIN committing because a fast-start failover may have occurred while it was Default value is 10 miliseconds. Application Continuity is supported for Oracle Data Guard switchovers to physical standby databases. Disable fast-start failover using the DGMGRL DISABLE FAST_START FAILOVER command. Starting the Observer Using Cloud Control. Observer uses the value of the DGConnectIdentifier property to connect to and monitor the primary and target standby databases. callout configuration scripts fsfo_precallout and The former primary database is disabled. This nomination is noted in the observer log file and in the broker log file (drc*.log). It is possible to manually perform a completer failover to a standby database that receives redo data from a far sync instance. 2. Overall Steps:-. Complete Failovers in Configurations Using Cascaded Standbys. When the primary database and the target standby database regain network connectivity, the broker will disable fast-start failover for the entire broker configuration. databases (PDBs) on any of the instances. In maximum availability mode, the behavior depends on the value of 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. 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. Use the wrapper script to start the observer process when the observer host boots or to restart it if it dies. This section describes how to stay on top of your FSFO environments. If there is only one registered observer, then it works in the same manner that a single observer worked prior to the advent of multiple observers in Oracle Database 12c Release 2 (12.2.0.1). Then, click Continue to proceed to the next page. But before enabling Flashback Database, you must enable Flash Recovery Area (FRA). The terminal session will appear to hang at this point. 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. A snapshot standby cannot be the target of a switchover or fast-start failover operation. When this command is issued, the actual Once the observer has initiated a fast-start failover, the primary database shuts down automatically. SQL> startup ORACLE instance started. 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. It is also supported for fast-start failover to physical standbys in maximum availability data protection mode. You can query the V$FS_FAILOVER_STATS view on the primary database to display statistics about fast-start failovers that have occurred on the system. multiple, inexpensive servers is the basis for the failover and other fault-tolerance features that RAC provides. In cases where Create a pre-callout script, or a post-callout script, or both. Bounce your database and verify database name its open mode and its role: SQL> shutdown immediate; ORA-01109: database not open Database dismounted. To start an observer, you must be able to log in to DGMGRL with an account that has the observer on ob2-host to become the master Data Guard uses Oracle Net (SQL*Net) for communication between the primary and standby databases and the FSFO observer. This configuration property establishes an acceptable limit, in seconds, that the standby is allowed to fall behind the primary in terms of redo applied, beyond which a fast-start failover will not be allowed. This section describes how to configure an Oracle Net connect descriptor that meets this requirement. Look for the desired data in the RAM. The following sections describe how to perform manual failovers: Reenabling Disabled Databases After a Role Change. FB Group:https://www.facebook.com/groups/894402327369506/ To change the FastStartFailoverTarget property to point to a different standby database, disable fast-start failover, set the FastStartFailoverTarget property, and reenable fast-start failover. The broker disables all of the physical and snapshot standby databases in the configuration. 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. Moorestown, New Jersey, United States. value is 10. Immediate Failovers in Configurations Using Cascaded Standbys. If you don't already have a Flash Recovery Area (FRA), you will need to create one for Flashback Database. Note that the FastStartFailoverThreshold property can be changed even when fast-start failover is enabled. The primary and target standby must have connectivity for the STOP OBSERVER command to complete successfully. Note that the new primary database does not need to be restarted. At a minimum, you must set db_unique_name. 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. 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. This is to ensure that the service definition gets propagated to the physical standby database via the redo stream and thus allows for the service to be started on the physical standby database. Do not attempt to reinstate the old primary database if an ORA-752 or ORA-600 [3020] error has occurred at the failover target. If you expect the network to be disconnected for a long time and The only exception to this is failovers to snapshot standby databases. If the primary is unable to contact the standby after a user specified period of time (NET_TIMEOUT option of log_archive_dest_ n), it drops out of synchronous transfer mode and begins operating as though it were in Maximum Performance mode. Fast-start failover will not occur unless all instances comprising the Oracle RAC primary database are perceived to have failed. After the database has been re-created, enable broker management of the re-created standby database by using the DGMGRL ENABLE DATABASE command. The following list indicates the extent to which fast-start failover is disabled in the broker configuration when the DISABLE FAST_START FAILOVER FORCE command is issued on the primary database, target standby database, and a standby database that is not the fast-start failover target. Configure the TNSNAMES.ORA file on the observer system so that the observer is able to connect to the primary database and to the pre-selected target standby database. Install the DGMGRL command-line interface on the observer computer as described in Oracle Data Guard Installation. A normal shutdown prevents a fast-start failover until the primary database and standby database are connected and communicating again. You can manage observers through either the Oracle Data Guard Overview pages in Cloud Control or using DGMGRL commands. time, if all the sessions that are connected though the active services In a Data Guard environment primary database is open in read write mode and the standby database in read only mode for reporting purpose. The default value is 30 seconds. SWITCHOVER command, and the databases are managed by Oracle operation can be automated using callout scripts. All Data Guard environments require the use of a password file in order to allow the databases to connect to each other. 1. If fast-start failover is already enabled, the When fast-start failover is disabled, no observer is called the master observer; all observers have the same functionality. Click Disable in the Fast-Start Failover wizard. An observer process is integrated in the DGMGRL client-side component of the broker and typically runs on a different computer from the primary or standby databases and from the computer where you manage the broker configuration. 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. When you configure data guard using OCI console, the default mode is set to maxprotection. All physical and snapshot standby databases will be disabled and must be re-created from a copy of the new primary database after a switchover to a logical standby database. So SALESRW will start on CHICAGO (which is now the primary) and SALESRO will start on BOSTON (which is now the physical standby). Now that we know switchovers work, it's time to test failovers. ASYNC. In addition to setting the configuration protection mode to maximum performance, you will also need to ensure that the LogXptMode database property for both the primary and target standby database is set to ASYNC. The FS_FAILOVER_STATUS column in the V$DATABASE view for the target standby database displays a reason why fast-start failover cannot occur. 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. observers are registered, a directory named Oracle Data Guard helps you change the role of databases between primary and standby using either a switchover or failover operation. After a failover, the original primary database can no longer participate in the Data Guard configuration. database. In this mode, the FastStartFailoverLagLimit configuration property is set to a non-zero value. The FORCE option may be the preferred method for disabling The ObserverPingInterval fast-start failover has not occurred to the target standby database. Flashing back a database is much faster and more seamless (one simple DDL statement) than traditional point-in-time or SCN-based recovery. 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. Each group that you define must have at least one broker configuration. Expected output is shown in blue text. Nothing will ruin your day faster than finding out that the standby the observer just failed over to is 12 hours behind in applying redo. Contains the observer log file for the broker configuration named specified, the file is stored in an appropriate directory under the broker's