Enabling Fast-Start Failover describes how to start observers as a part of the step-by-step process to enable fast-start failover. All other registered observers are considered to be backup observers. Look for the desired data in the RAM. In the following example commands, a service named PAYROLL is configured to be active in the PRIMARY role on the primary database NORTH. Testing FSFO failover requires simulating loss of the primary. A snapshot standby cannot be the target of a switchover or fast-start failover operation. The connect descriptor can be configured in one of two ways: Oracle Database PL/SQL Language Reference for more information about the DB_ROLE_CHANGE system event. On Linux/Unix, the directory specified by the DG_ADMIN environment This page will not allow you to alter the protection mode. 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. (Note: adds the StaticConnectIdentifier Broker database property to allow you to specify a different service name.) You can optionally indicate the database health conditions that should cause fast-start failover to occur. See Oracle Enterprise Manager Command Line Interface. Oracle Data Guard configuration with DGMGRL. stored in the specified path using the default file names. Therefore, the target standby never falls behind the primary If it's not, DGB will not allow the failover to continue until the DBA has manually resolved any discrepancies. 1)What are the steps to do Switchover/Failover operation manually in 2-node RAC and 2-node DATAGUARD environment. To verify the observer is started and the configuration is ready for As mentioned above, Maximum Availability mode is mandatory for Oracle Database 10g and optional for Oracle Database 11g. In such a case, no attempt is made to transmit any unsent redo from the cascader to the terminal standby. If the target is a snapshot standby database, the broker first converts the database to a physical standby database. LGWR is unable to write to any member of the log group because on an I/O error. Client-side broker 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. If the database is not enabled, you will not be able to perform a failover to this database. list of the observers that can become the master observer when that STANDBY>ALTER DATABASE OPEN; After the conversion, the broker will start Redo Apply to apply accumulated redo data, before failing the database over to the primary role. FS_FAILOVER_OBSERVER_HOST shows the name of the computer on which the master observer is running, FS_FAILOVER_OBSERVER_PRESENT shows whether or not the master observer is connected to the local database. The default Data Guard Switchover/failover to standby The standby database will be activated to serve as the primary database at some point in its life cycle. Media Recovery - Once the restore is complete, recovery proceeds as a typical media recovery, applying redo from archived and online redologs and rolling back uncommitted changes with undo. In Oracle RAC configurations, the Inaccessible Logfile and Stuck Archiver health conditions may only be applicable to a single instance. Check the spelling of your keyword search. 12c upgrade, The below commands will help to bring up standby as primary, https://www.linkedin.com/in/hari-prasath-aa65bb19/, https://www.facebook.com/groups/894402327369506/. If the database is managed by Oracle Clusterware, broker does not open any of the The only exception to this is failovers to snapshot standby databases. Maximum Availability mode uses synchronous redo transfer and FSFO imposes the additional requirement that the redo is recorded in the standby redo log (SRL) of the target standby (AFFIRM option of log_archive_dest_ n). If there are many actions that need to take place, put them in a separate script and use the trigger to run the script in an orphan process or thread independent of the database. 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. You can specify STOP OBSERVER ALL to stop all observers registered in a broker configuration. 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. Being FSFO ready means that all conditions are met for a successful failover, including having a running observer and sufficient redo transmitted to the failover target to meet durability requirements. Disable fast-start failover using the DGMGRL DISABLE FAST_START FAILOVER command. This list describes how the overall Oracle Data Guard protection mode is handled after a manual failover (complete or immediate). The group of broker configurations to be managed is declared in the observer configuration file. client-side broker files, the specified values are used. After the restart, Redo Apply begins applying redo data from the new primary The simple tests described in this guide are fine for making sure the basics are working, but you'll probably want to develop a more comprehensive set of tests suited to your environment and requirements. A switchover guarantees no data loss and is typically done for planned maintenance of the primary system. These scripts must be in the same directory as the required permissions, the admin folder is created We'll start with switchovers. If only a path is specified, the files are 2. The broker reinstates bystander standby databases that were disabled during a failover as standby databases to the new primary database. Stopping the observer does not disable fast-start failover. gets enabled and then begins monitoring. 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. Have a means of notifying someone if standby apply falls too far behind. Use broker configuration properties to set the time taken to detect a When a switchover is started, the primary and standby databases that are involved should have as small a redo lag as possible. We suggest you try the following to help find what youre looking for: This document will guide you through configuringOracle Data GuardFast-Start Failover (FSFO) using a physical standby database. See theFlashback Database section above for information on storage requirements. Regardless of the method you choose, the broker coordinates the role transition on all databases in the configuration. See Disabling Fast-Start Failover. If any errors occur during either conversion, the broker stops the switchover. This table describes the optional database properties that you can set. 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. FastStartFailoverLagLimit property. The Initiate reinstatement by mounting the database. Choosing a Target Standby Database for Switchover and Choosing a Target Standby Database for Failover provide guidelines to help you choose a target standby database. The following example shows you how to set up more than one service on a database and how using the broker ensures that the correct service starts on the correct database. 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. broker does not allow the primary database to commit transactions until it has regained For zero data loss in maximum availability mode, the FastStartFailoverLagLimit property must be set to zero. Using the db_unique_name of each database as the Oracle Net alias is simple and intuitive. Whether or not you need the FORCE option depends mostly on if the primary and target standby database have network connectivity: If the primary and target standby database have network connectivity, and the database to which you are connected has network connectivity with the primary database, the FORCE option has no effect. After step 1 finishes, Switch the original physical standby db STAN to primary role; If the primary database does not have connectivity with the target standby database, fast-start failover remains enabled on the target standby database and the observer may still attempt a fast-start failover if conditions warrant a failover. command on the observer computer: The observer is a continuously executing process that is If reinstatement of a database fails, its status changes to ORA-16795: the standby database needs to be re-created. Oracle Data Guard provides the ability to create and maintain Standby databases at one or more sites These protect Oracle databases from database and server failures as well as site disasters Failover to one of the alternate sites can be set to happen automatically (fast-start failover) or manually if the primary database is not usable See Sources of Diagnostic Information for details about the broker's drc* log files. Default value is 100 See the Cloud Control online help for more information. the SYSDG or SYSDBA privilege. Initiate the switchover on the primary database PRIM: This may take a few minutes. If there is only one standby database in the configuration, you can skip this step and continue with Task 3. There are configuration requirements that must be met in order to publish and properly handle FAN events generated as the result of a broker-managed failover. Note that enabling FSFO does not make the configuration ready for automatic failover - that requires an observer, which we'll get to next. While this eliminates the processing overhead associated with periodically establishing a new observer connection to the primary database, it also prevents the observer from detecting that it is not possible to create new connections to the primary database. environment variable must have exclusive permissions wherein it can be accessed only If the target is a snapshot standby database, the broker first converts the database back to a physical standby and then starts Redo Apply to apply all the accumulated redo before completing the failover and opening the database as a primary database. 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 observer is perfectly satisfied if all of the redo it needs to meet your durability requirements has been received by the failover target. The observe-only mode for fast-start failover enables you to test how fast-start failover will work in your environment. 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. configuration file exists. SQL> Select Database_role from v$Database; When you select a standby database to be the next primary database after a switchover or a failover, there are several factors to consider. SQL>SHUTDOWN IMMEDIATE; You may failover to a snapshot standby database. file also declares broker configurations and defines configuration The observer maintains state information in a file. The time interval starts when the observer first loses its connection to the primary database. 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. If you already have an FRA, you may need to increase its size in order to accommodate the Flashback Database files. connection, or the database on which you issued the disable fast-start failover If you want the broker to skip this viability check of bystander standby databases during a complete failover, thus decreasing the overall failover time, set the BystandersFollowRoleChange configuration property to NONE. At this point, you can either: Disable fast-start failover (described in Disabling Fast-Start Failover) and attempt to open the former primary database, Manually reinstate the former primary database, as described in Reenabling Disabled Databases After a Role Change. 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. 4. configuration named ConfigurationSimpleName. If the currently configured mode is maximum protection, Cloud Control will downgrade the mode to maximum availability. All standbys other than the failover target are considered bystanders (v$database.fs_failover_status = 'BYSTANDER'). For example, if the old standby was a physical or snapshot standby, then the old primary must be re-created as a physical standby. An immediate failover should only be performed when a complete failover is unsuccessful or in the error cases just noted. Choose a value high enough to avoid false disconnects from intermittent network trouble. Another good test is to simulate network failures that leave the primary up, but isolated from the failover target standby and the observer. Determining a Database's Readiness to Change Roles. Simply use DISABLE FAST_START FAILOVER. See Oracle Data Guard Concepts and Administration for more information on using the ALTER SYSTEM FLUSH REDO statement. Rather, fast-start failover will be enabled in accordance with the current protection mode. Another standby database that does not have connectivity with the primary database, fast-start failover is disabled for this database. Other logical standby bystander databases in the broker configuration will remain viable after the switchover. usually within three seconds if fast-start failover is enabled. For the RMAN duplicate active database method, the init.ora file (initdb1.ora in the example) requires only one parameter: db_name (it doesn't even have to be the real name of the database - any name will do). If a failure occurs once a reinstatement operation (automatic or manual) is underway, the broker logs the appropriate information in the broker configuration files and broker log files. observer computer is returned to you so that you can continue to specified, the file is stored in an appropriate directory under the broker's SQL> startup ORACLE instance started. It also requires Flashback Database to be enabled on both the primary and target standby databases. This method will disable fast-start failover on all databases in the broker configuration. Fast-Start Failover in Oracle 11g Data Guard. Flashback Database records the before-image of changed blocks. session. Broker changes database parameters during startup and role transitions via ALTER SYSTEM commands. 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 Create or update the fast-start failover callout configuration file and include It's generally a good idea to store the state file in a directory associated with the database to avoid locking issues when running multiple observers on the same host. issue commands and interact with the broker configuration. Verifies that the primary and the target standby databases are in the following states: The primary database is enabled and is in the TRANSPORT-ON state. These are some points to consider before you begin a switchover. Starting with (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.
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