observers are registered, a directory named The reinstated database acts as the fast-start failover target for the new primary database, making a subsequent fast-start failover possible. Fast Start Failover in Data Guard - ORACLE-HELP primary database must have network connectivity. The FS_FAILOVER_OBSERVER_PRESENT column, which indicates whether the observer is running and actively pinging the database. fsfo_postcallout are stored in the same location as The minimum detection time is 6 seconds, which is the default Automatic failover quickly and reliably fails over the standby Autonomous database to the primary database role, without requiring you to perform any manual steps. lower detection times for primary database failures, you must To proceed, you must first disable fast-start failover using the FORCE option, and then perform a manual failover. The examples shown in this section do not necessarily show the specific attributes you might need to use in your own environment. In this example, the original primary data is called PRIM and the original standby database is called STAN. 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. Stopping a Specific Observer When There are Multiple Observers. Log in as a test user and make some changes that won't impact other parts of the system. 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. the Steps To Congure Oracle 11g Data Guard Physical Standby associate that we give here and check . fast-start failover to the target standby database if conditions warrant a failover. The target standby database is enabled and is in the APPLY-ON state. Immediate Failovers in Configurations Using Cascaded Standbys. The log file name is specified with the LOGFILE IS option of the START OBSERVER command. The broker selects a target standby based on the order they are specified in the property. On Windows, the directory specified by the DG_ADMIN 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. Provides an automatic failover environment 3. To protect the files, it's good practice to store them in separate filesystems. Reinstatement will have to be accomplished by other means (manual or scripted Broker commands). What to do in case of failover: (Important note: Istanbul is the primary server and Baku is the standby server) 1. If you do not want to use the default, you can define a specific group. fast-start failover has not occurred to the target standby database. file, observer runtime data file (fsfo.dat), fast-start failover callout Observers should be installed and run on a computer system that is separate from the primary and standby systems. Broker keeps its configuration details in flat file. client-side broker files, the specified values are used. 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. Set both these properties to achieve a primary failure detection time of 1 A normal shutdown uses SHUTDOWN NORMAL, SHUTDOWN IMMEDIATE, or SHUTDOWN TRANSACTIONAL. After step 1 finishes, Switch the original physical standby db STAN to primary role; Databases that can be reinstated will have the following status value: For the REINSTATE command to succeed, Flashback Database must have But it will also continue trying to reconnect to the primary database indefinitely. 11.2 rac servicefailover 2020-01-28 ORACLE ORACLE RAC/ASM RAC112. In Dataguard switchover and failover steps in Oracle 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. After the patch has been successfully applied to all databases, take the following steps to enable fast-start failover and start the observer. The foundation of FSFO is Data Guard - a primary and at least one standby. The following paragraphs describe the supported availability modes. 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). REINSTATE REQUIRED is present only after fast-start failover has occurred and shows on both the new primary database and the database undergoing reinstatement. You must determine which available standby databases should be targets for failover. This walkthrough assumes that all ORLs and SRLs on the primary and standby databases are the same size. Therefore, the primary database can continue processing transactions, even if the target standby database fails. A snapshot standby cannot be the target of a switchover or fast-start failover operation. If no value is specified for the broker configuration, you must connect through another DGMGRL client If there is only one standby database in the configuration, you can skip this step and continue with Task 3. The remaining Data Guard-related parameters will be set by Broker later in the walkthrough. If the PreferredObserverHosts property is set for the current This list describes how the overall Oracle Data Guard protection mode is handled after a manual failover (complete or immediate). There is no data loss during a switch-over. Reference architectures for Oracle databases on Azure - Azure Virtual 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. To start the observer with DGMGRL, issue the following For example, if the old standby was a physical or snapshot standby, then the old primary must be re-created as a physical standby. standby database, host, or network failure, etc.). DNS CNAME) that always resolves to the primary. Oracle Data Guard can switch a standby database to the primary role in case a production database becomes unavailable due to . 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. You cannot create the standby DB system in a different AD from the primary DB system. data (in seconds) specified by the The broker continuously monitors for all sessions that are connected Else, broker restarts the new This section lists the steps the master observer takes to determine if a fast-start failover is needed and then to perform one, if necessary. Your email address will not be published. 8.2 Private Cloud Appliance and . You must use the Oracle wallet to store the credentials for all broker configurations to be managed. For more details about managing redo transport services using database properties, see Managing Redo Transport Services. primary. Oracle Data Guard configuration with DGMGRL. If you already have an FRA, you may need to increase its size in order to accommodate the Flashback Database files. These conditions are described in the following table: Dictionary corruption of a critical database. Perform a switchover to a standby database that is not configured as the fast-start failover target, Perform a switchover to the target standby database in a configuration operating in maximum availability mode, unless the standby database is synchronized with the primary database, Perform a switchover to the target standby database in a configuration operating in maximum performance mode, unless the standby database is within the lag limit of the primary database. If both HVR and Data Guard were running without latency or if no changes were made to the source database at the time of the failover, it can be assumed that all databases are synced and the no extra steps are necessary; the steps for Graceful Failover can be followed. The real test of the configuration is a successful role transition in both directions with both switchover and FSFO failover. 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. Flashing back a database is much faster and more seamless (one simple DDL statement) than traditional point-in-time or SCN-based recovery. restart the new physical standby database. Switches roles between the primary and standby databases. Verify the configuration from both hosts. callout configuration scripts fsfo_precallout and If the DG_ADMIN environment variable is not set, or the The default If the value is non-zero, failover is possible any time the standby database's apply When querying the V$DATABASE view, pay special attention to the following: The FS_FAILOVER_STATUS column, which can contain the values described in Table 6-2. 3. Displays the current fast-start failover mode. 2. If there are physical or snapshot standby databases in the configuration and the switchover occurs to a logical standby database, you need to re-create those databases from a copy of the new primary database and then reenable those databases, as described in Reenabling Disabled Databases After a Role Change. OBSERVER command, if this directory does not have the To avoid the overhead of recording every change to every block, Flashback Database takes a "fuzzy" snapshot every 30 minutes and only records the before-image block upon its first change since the last snapshot. Ideally the primary, standby, and observer will be in geographically separate areas. Issue the following command while connected to any database in the broker configuration, except the database that is to be reinstated: The newly reinstated standby database will begin serving as a standby database to the new primary database. fast-start failover when: A network outage isolates the primary database from the observer and the target standby database before conditions exist that warrant a failover. Each observer has its own log file. To get started, all you'll need is Oracle Database Enterprise Edition Release 10.2 or later, a database, and three hosts: two for the databases and a small host for the FSFO observer. A value of TRUE helps to ensure that an isolated primary database cannot satisfy user queries. The column value for V$DATABASE.FS_FAILOVER_STATUS will be SYNCHRONIZED in a configuration operating in maximum availability mode, and it will be TARGET UNDER LAG LIMIT in a configuration operating in maximum performance mode when ready to fast-start failover.
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