data guard failover steps

Starts redo transport services to begin transmitting redo data to all bystander standby databases that were not disabled. More specifically, we can have an asynchronous second read-only Managed instance in the same or in a different region. Regards, Narottam Tagged: dataguard dba rac Welcome! You want to prevent fast-start failover from occurring because the primary database will resume service soon. A high lag limit may lead to more data loss but may lessen the performance impact of the primary database. The examples shown in this section do not necessarily show the specific attributes you might need to use in your own environment. This section describes how to configure an Oracle Net connect descriptor that meets this requirement. SET ObserverConfigFile used to specify a customized observer configuration file. Broker stores it configuration information in a mirrored set of files outside the database. For example: The default value for the FastStartFailoverThreshold property is 30 seconds and the lowest possible value is 6 seconds. Select name,open_mode,database_role from v$database; Step:2 Cancel the MRP process If the broker performs a switchover or failover, then it starts the service SALESRW or SALESRO based on the current role of the database. For any work, queries and help. observer name, host, whether it is the master observer, when it became the master 12c upgrade, The below commands will help to bring up standby as primary, https://www.linkedin.com/in/hari-prasath-aa65bb19/, https://www.facebook.com/groups/894402327369506/. FastStartFailoverLagLimit configuration property is set to zero) or The primary and target standby must have connectivity for the STOP OBSERVER command to complete successfully. Step-B: Copy control file to temporary location on primary database. Regardless of the method you choose, the broker coordinates the role transition on all databases in the configuration. failure on the primary database. If both the observer and designated standby database lose connectivity with the primary database for longer than the number of seconds specified by the FastStartFailoverThreshold configuration property, the observer will initiate a fast-start failover to the standby database. Databases that can be reinstated will have the following status value: For the REINSTATE command to succeed, Flashback Database must have This page will not allow you to alter the protection mode. This walkthrough assumes that all ORLs and SRLs on the primary and standby databases are the same size. file, observer runtime data file (fsfo.dat), fast-start failover callout This is SET MASTEROBSERVER TO allows you to manually change the observer configuration file. Issue the following SRVCTL commands so that both databases in the Data Guard configuration know about the two potential services for each database: To start things up initially, you must manually start the services on the right node. Your email address will not be published. You can query the V$DATABASE view to verify that the observer is started and the configuration is ready for fast-start failover. For Maximum Availability environments, change this to synchronous. For this build, we will use a single physical standby 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. This property is measured in The target standby database is enabled and is in the APPLY-ON state. In maximum availability mode, set the LogXptMode database property for both the primary and target standby databases to SYNC or FASTSYNC. callout configuration file. Switchover to a logical standby database is disallowed when the configuration is operating in maximum protection mode. configuration file, and fast-start failover callout script files. Install the DGMGRL command-line interface on the observer computer as described in Oracle Data Guard Installation. Notice that the terminal session appears to hang after starting the observer. If you cannot tolerate any loss of data, then ensure that the configuration protection mode is set to maximum availability or maximum protection. through these services to exit or for the specified wait time 5. When enabling fast-start failover, the broker verifies that the property indicates an existing standby. instructions for the DGMGRL command-line interface. In such a case, no attempt is made to transmit any unsent redo from the cascader to the terminal standby. 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. the primary role, use the PreferredObserverHosts The Some properties have changed between those releases. If Flashback Database history is insufficient, the observer will not be able to reinstate and you will have to manually reinstate from backup or by primary duplication. This is because the -role qualifier is taken into account only by Data Guard broker, and at database startup. Add the primary database and each standby database to the address list. If the value is zero, the standby must alter system set standby_file_management=auto; This parameter must be set before the primary can be opened in Maximum Availability mode. Before enabling fast-start failover, use one of the following techniques Reinstate or re-create standby databases in the configuration that were disabled by the broker. isolated. The old Primary must have been running in flashback mode before the failover. there is a lost network connection, be aware that the observer may attempt a observer is still in contact with the standby. If the protection mode was at maximum availability or maximum performance, it remains unchanged. 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. Restore - Flashback Database restores the datafiles to the closest snapshot prior to the specified SCN. During failover, bystanders "follow" the primary by default, flashing back and reapplying redo from the new primary as necessary. enabling fast-start failover. Another consequence of immediate failover is that all other databases in the configuration are disabled and must be reinstated or re-created before they can serve as standby databases for the new primary database. Make sure everything is working before moving on. Whenever possible, you should switch over to a physical standby database: If the switchover transitions a physical standby database to the primary role, then: The original primary database will be switched to a physical standby role. Unless action is taken to change the failover target to one of the bystanders, the new primary will be without a failover target until the former primary is reinstated as a standby. The remaining Data Guard-related parameters will be set by Broker later in the walkthrough. Do not use Shared Server (formerly MTS) for Data Guard. must create a .suc and .err file in the Choosing the standby database with the smallest transport lag can minimize the amount of data loss and in some cases, incur no data loss at all. Writing the wrapper itself and the means to determine when to execute it are up to you. Change the failover target to the standby being switched over to, Change the failover target to the desired standby. Contains the observer log file for the broker configuration named FSFO can provide substantial gains in high availability and disaster recovery preparedness for all environments, from inexpensive Cloud-based systems to global distributed data centers. When DGMGRL starts, if the DG_ADMIN Steps to Create a Physical Standby Databa se 3 -3 Preparing the Primary Database 3 -4 FORCE LOGGING . On the Oracle Data Guard Overview page next to the Fast-Start Failover status field, click Disabled to invoke the Fast-Start Failover page. The failed primary database requires reinstatement as a new standby database to the new primary. If that metadata is pushed out, Oracle can no longer find a fuzzy snapshot so it will not be able to flash back. Stores the observer runtime data file and observer configuration file in 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. computer, it automatically starts the observer when you enable 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. The observer is the third party in an otherwise typical primary/standby Data Guard configuration. fast-start failover. To move the observer to another computer: There is no need to disable fast-start failover when you move the observer. Only two databases, the primary and the failover target, can be in the FSFO configuration at any given time. The word manual is used to contrast this type of failover with a fast-start failover (described in Fast-Start Failover). The pre-callout script Note that this does not guarantee no data will be lost. The redo transport mode used to send redo to the target standby database or the database currently in the primary role. Steps for FAILOVER the Dataguard environment 1. The general approach seems to be CDB level failover to standby , so the failover takes place at CDB to CDB , in an event where a single PDB is experiencing an issue , we will have to failover the whole instance ..this will impact all PDB's on the CDB. The standby VM (myVM2) has the Oracle software installed only. A trigger on the DB_ROLE_CHANGE system event can be used to update the naming service and, with the proper client cache TTL settings, clients can connect to the new primary very quickly. 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. Archiver is unable to archive a redo log because the device is full or unavailable. If a single-instance primary database (either Oracle RAC or non-Oracle RAC), or if all instances of an Oracle RAC primary database are shut down with the ABORT option, the observer attempts a fast-start failover. 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. DG_ADMIN environment variable is not set, the files are stored in A fast-start failover to the target standby database fails. Oracle Database PL/SQL Packages and Types Reference, Stop the observer from any computer system in the broker configuration, as described in, Start the observer on the new computer system, as described in Step 8 of, Enable fast-start failover using the DGMGRL, Shut down the primary database and the target standby database using either DGMGRL, Oracle Database Global Data Services Concepts and Administration Guide, Oracle Real Application Clusters Administration and Deployment Guide, Configure the connect descriptor for connect-time failover. Clusterware: The broker notifies Oracle Clusterware to stop active Broker will validate the configuration, set parameters on both databases, and start managed recovery. fsfocallout.ora. Data Guard Configuration Details:-. To perform specified actions before or after a fast-start failover See Oracle Data Guard Concepts and Administration for more information on using the ALTER SYSTEM FLUSH REDO statement. If the primary and target standby databases do not have network connectivity or if the database to which you are connected does not have network connectivity with the primary database, consider using DISABLE FAST_START FAILOVER with the FORCE option. Thus, the validity of the values of these properties is not verified until after the switchover. After the conversion, the broker will start Redo Apply to apply accumulated redo data, before failing the database over to the primary role. 2. A failover may or may not result in data loss depending on the protection mode in effect at the time of the failover. This can be done regardless of whether the failover was done to a physical, logical, or snapshot standby 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. If no value is specified for the 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. When this command is issued, the actual The standby database must be re-created or reinstated before it can serve as a standby for the new primary database. For example: In the following example, assume the network between the primary database and the observer has failed. If the protection mode was at maximum protection, it is reset to maximum performance. If this Neither the primary database nor the logical standby database needs to be restarted after the switchover completes. data (in seconds) specified by the Starting the Observer Using Cloud Control. The failover was to a logical standby database. Make sure the last redo data transmitted from the Primary database was applied on the standby database. After the fast-start failover completes successfully, the master observer will attempt to reinstate the former primary database as a new standby database when a connection to the former primary database is reestablished, and the FastStartFailoverAutoReinstate configuration property is set to TRUE. commands. 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. In addition, the primary database will shut down if it perceives a loss of connectivity for a period longer than FastStartFailoverThreshold seconds, if the FastStartFailoverPmyShutdown configuration property is set to TRUE. 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. directory. 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. But it will also continue trying to reconnect to the primary database indefinitely. These commands can be issued from the DGMGRL command line, but it is not necessary to log on prior to using them. For more information, see SET MASTEROBSERVER TO. Do not attempt to reinstate the old primary database if an ORA-752 or ORA-600 [3020] error has occurred at the failover target. In these sample commands, the ellipse () signifies any other add service options you wish to supply. Note that role changes to logical standby databases always result in physical standby database bystanders being disabled. It will also alert you to databases that have had Flashback Database disabled at some point after FSFO was enabled. drain_timeout amongst the active services. Displays on the primary database after loss of connectivity to the target standby database and the change to the UNSYNCHRONIZED state (maximum availability mode) or to the TARGET OVER LAG LIMIT state (maximum performance mode) cannot be confirmed by either the target standby database or the observer. For example, if the old standby was a physical or snapshot standby, then the old primary must be re-created as a physical standby. Upon detecting the break in communication, the observer attempts to reestablish a connection with the primary database for the amount of time defined by the FastStartFailoverThreshold property before initiating a fast-start failover. Many customers use Oracle Database deployed on Amazon Elastic Compute Cloud (Amazon EC2) to run their Oracle E-Business Suite applications. Starting with 10.2.0.4 (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. Use Cloud Control or DGMGRL to perform either a complete (recommended) or an immediate failover. You need to consider all of the options at the time you are building your Oracle Data Guard configuration, including factors such as the characteristics of physical standbys versus logical standbys versus snapshot standbys, the network latency to your standby database sites, the computing capabilities at a future primary database site, and so on. 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. It is then started and stopped on the primary database. If errors occur during the disable operation, the broker returns an error message and stops the disable operation. Fast-start failover is faster when you take steps to optimize recovery so that the application of redo data to the standby database is kept up to date with the primary database's rate of redo application. Broker checks to see if Flashback Database is enabled on the primary and failover targets when FSFO is enabled.

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