data guard failover steps data guard failover steps

status before the crash. SQL> Select Database_role from v$Database; standby database is mounted, broker remembers this setting. To avoid problems due to timing variations, values less than 60 minutes are not recommended and values of 30 or less virtually guarantee Flashback Database failure. To help you select an appropriate switchover or failover target, use the following DGMGRL commands which perform checks on the database to determine its readiness to complete a role change. Steps to Create a Physical Standby Databa se 3 -3 Preparing the Primary Database 3 -4 FORCE LOGGING . The Oracle Database 11g observer can make use of specific credentials, allowing the same wallet to be used for multiple observers with different SYS passwords. If local_listener is already in use, add the Data Guard listener to the list. Each database in a Data Guard configuration must have a unique name. 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. 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. this directory are used to store the files related to the required permissions, fast-start failover callouts will fail. File. DGMGRL. Although the default value of 30 seconds is typically adequate for detecting outages and failures on most configurations, you can adjust failover sensitivity with this property to decrease the probability of false failovers in a temporarily unstable environment. For each temporary table, verifying that temporary files associated with that table on the primary database also exist on the standby database. The master observer waits the number of seconds specified by the FastStartFailoverThreshold configuration property before attempting a fast-start failover when the primary database has crashed or has lost connectivity with the observer, as in the following situations: The primary database loses its connections with both the observer and target standby database. The observe-only mode for fast-start failover enables you to test how fast-start failover will work in your environment. Alternatively, if you intend to switch back to the original primary relatively soon, then you may re-enable the disabled standby databases after the switch back. See Troubleshooting Problems During a Switchover Operation for more information. $DG_ADMIN/config_ConfigurationSimpleName/callout For example: Using DGMGRL, you can do this by examining the output of the SHOW CONFIGURATION LAG. This is because the -role qualifier is taken into account only by Data Guard broker, and at database startup. Twitter:https://twitter.com/hariprasathdba, In A single-instance database must be registered with Oracle Restart in order to publish FAN events via ONS. 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. Manual failover to the fast-start failover target can be performed without receiving an acknowledgement from the observer. Reinstating the Former Primary Database in the Broker Configuration for more information about reinstatement. lag is less than or equal to the value specified by the Have a means of notifying someone if standby apply falls too far behind. 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. For each broker configuration on which one or more A database in the primary role will not open until it has verified with the observer that it is still the primary. alter database recover managed standby database cancel; Step:3 The below commands will help to bring up standby as primary. You can start, stop, and show observers for a group of configurations. 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. If failover is not possible for some reason, then the master observer will continue checking whether the standby database is ready to fail over. PDBs. Any database that was disabled while multiple role changes were performed cannot be reinstated. operation. US Coast Guard Auxiliary. If there is more than one standby database in the configuration, you must explicitly set the FastStartFailoverTarget property on the primary database to name one or more candidate target standby databases. 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. Configure the protection mode. Provides an automatic failover environment there is a lost network connection, be aware that the observer may attempt a Immediately after issuing command in step 2, shut down and restart the standby instance STAN: For systems with multiple RAID controllers, consider creating SRLs such that their IO is balanced across the controllers. Make sure the last redo data transmitted from the Primary database was applied on the standby database. The observer's main purpose is to enhance high availability and lights out computing by reducing the human intervention required by the manual failover process that can add minutes or hours to downtime. When enabled, re-create the standby database. If you have not used the SET ObserverConfigFile command after starting the current DGMGRL client, then the result will always be: ObserverConfigFile=observer.ora. If errors occur during the disable operation, the broker returns an error message and stops the disable operation. To start the observer with DGMGRL, issue the following Broker Configuration Has Multiple Registered Observers. To verify this change, again query the Database_role column of V$DATABASE. 8.2 Private Cloud Appliance and . PRIM>SHUTDOWN IMMEDIATE; Starting Observers as Background Processes. Event notification and database connection failover support is available to database clients connected to local database services when a broker-managed failover occurs. Performing a Manual Failover Task 1: Determine Which of the Available Standby Databases is the Best Target for the Failover, Performing a Manual Failover Task 2: Start the Failover, Performing a Manual Failover Task 3: Reset the Protection Mode, Performing a Manual Failover Task 4: Re-establish a Disaster-Recovery Configuration. failover configuration file, this script is run. Restore - Flashback Database restores the datafiles to the closest snapshot prior to the specified SCN. Select name,open_mode,database_role from v$database; Step:2 Cancel the MRP process data (in seconds) specified by the You can specify STOP OBSERVER ALL to stop all observers registered in a broker configuration. fast-start failover succeeds, if a post-callout script is specified in the fast-start On primary database NORTH, execute the following: On standby database SOUTH, execute the following: Services that are to be active while the database is in the physical standby role must also be created and started on the current primary database regardless of whether the service will be started on that database or not. You must specify it every time you start a new DGMGRL client. maximum availability and maximum performance modes, to avoid a When DGMGRL starts, if the DG_ADMIN You can also reinstate bystander standby databases that were disabled during a failover operation. directory has the same permissions as its parent directory. SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY; If you have an Oracle RAC primary database, consider specifying a higher value to minimize the possibility of a false failover in the event of an instance failure. Some properties have changed between those releases. 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. the SYSDG or SYSDBA privilege. Commit latency is not affected by redo transfer, but committed transactions whose redo has not been received by the standby will be lost during failover. November 20, 2009. 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. Once the Oracle instance is transitioned into primary database status in either switchover or failover, the life of the database as the standby ends and its service as the primary database . This can be avoided by first disabling fast-start failover with the FORCE option on the target standby. configuration file 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. With a value of TRUE for this property, the primary will shut down after being stalled for the number of seconds specified by the FastStartFailoverThreshold property. If the database is not enabled, you will not be able to perform a failover to this database. Here's a one-liner observer startup for *nix. Therefore, the detection time can be reduced to nearly The existence of a .suc file, Managed recovery process has been stopped between primary and standby database and standby becomes primary database. What is true about Data Guard setup with fast-start failover? Read-Only Standby and Active Data Guard The minimum detection time is 6 seconds, which is the default In maximum availability mode, the behavior depends on the value of the The target standby database is synchronized with the primary database if it is a configuration operating in maximum availability or maximum protection mode, or the target standby database is within the lag limit if it is a configuration operating in maximum performance mode. Your email address will not be published. 1. After an immediate failover completes, all the standby databases in the configuration, regardless of their type, are disabled. Starting the Observer Using Cloud Control. Before enabling fast-start failover, use one of the following techniques the observer was killed after the stall began, but before the failover timeout had elapsed). The advanced way is in the following article: Connect-Time Failover by a Dynamic Service Name. After a role change, the naming service can be updated with the new primary's address. callout configuration file. directory. If block change tracking is enabled on the primary, and the target Is possible if the target standby database displays SYNCHRONIZED and the FS_FAILOVER_OBSERVER_PRESENT column displays YES. lower detection times for primary database failures, you must That process is shown here. 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. Disable fast-start failover using the DGMGRL DISABLE FAST_START FAILOVER command. This allows Data Guard to remain functional during maintenance periods when the application listeners are down. Role Transitions: Switchover and Failover 1 -7 Oracle Data Guard Broker Framework 1 -9 C hoosing an Interface for Administering a Data Guard Configuration 1 -10 Oracle Data Guard: Architecture (Overview) 1 -11 Primary Database Processes 1 -12 . You will have to reinstate or re-create (see Reenabling Disabled Databases After a Role Change) the standby databases after failover has completed. Oracle 12c-Step by Step Manual Data Guard Switchover, Manual Upgrading Oracle Database From 11.2.0.4 to 12.2.0.1, Automatically Terminated The Blocking Session By Setting MAX_IDLE_BLOCKER_TIME, Apply Patching On Oracle 21c Database Release Update 21.7.0.0.0, Oracle 21c Point In Time Recovery of Pdb Database, Oracle 21c Cloning a PDB Database Using Sqldeveloper Tool. Clusterware: The broker notifies Oracle Clusterware to stop active failure on the primary database. If the currently configured mode is maximum protection, Cloud Control will downgrade the mode to maximum availability. In this case, disable fast-start failover using the FORCE option on the target standby database. The broker controls the rest of the switchover. fsfocallout.ora. (Note that the target standby cannot be a far-sync instance. It behaves similarly to START OBSERVING and STOP OBSERVING to operate on all the configurations defined in the observer configuration file. If you will be using RMAN to create the standby database, it also needs a static service to restart the database being created. For reliable startup, the initial connection should always be made to the primary. If the new primary database was a primary database in the past, and had block 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. By default, the observer creates this file in the current working directory when it is started and names the file fsfo.dat. You can find detailed information about all observers, including master observers and backup observers, in the V$FS_FAILOVER_OBSERVERS view. configuration named ConfigurationSimpleName. on particular instances based on the service configuration. Such preparation includes: Ensuring that standby redo log files are configured on the primary database. This list contains some recommendations to obtain better performance when using fast-start failover. In these sample commands, the ellipse () signifies any other add service options you wish to supply. Alternatively, use the RedoRoutes property to configure the redo transport mode for the target standby and the database currently in the primary role. Verify dmon process is running and broker parameters viz. To run an observer as a background process, use the DGMGRL command START OBSERVER IN BACKGROUND. SQL> Select Database_role from v$Database; Note that these properties only affect whether primary shutdown and automatic reinstatement are performed if a fast-start failover occurs because the primary crashed or was isolated from the observer and target standby database. SQL> Select Database_role from v$Database; For Oracle RAC databases, see Oracle Real Application Clusters Administration and Deployment Guide for more information about configuring database services with the SRVCTL utility. callout configuration scripts fsfo_precallout and Then the STOP OBSERVER command can be issued successfully on the former master observer. You must ensure that the primary database is shut down prior to performing a manual failover. Complete Failovers in Configurations Using Cascaded Standbys. from another DGMGRL session. 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 Broker stores it configuration information in a mirrored set of files outside the database. If no name is specified for the observer then a default observer name, the host name of machine where the START OBSERVER command is issued, is used. There is no impact on your current configuration or on applications. 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. 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. The real test of the configuration is a successful role transition in both directions with both switchover and FSFO failover. In addition, some standby databases may be disabled by the broker during the failover if the broker detects that they have applied redo beyond where the new primary database had applied. This file Starting with Oracle Database Release 21c, use the DG_ADMIN the names of the scripts created in the previous step. After fast-start failover is enabled and up to four observers are started, one observer is nominated as the master observer that continuously monitors the environment to ensure the primary database is available. The same thing happens if a shutdown and startup of either database occurs - the service that is started is the one that matches the role of the database being started. If the DG_ADMIN environment variable is not set, or the This is a good time to enable FSFO to make sure that all of the prerequisites have been met. To enable fast-start failover in Cloud Control, use the Fast-Start Failover wizard. 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. The command SHOW OBSERVER provides detailed information about registered observers. 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. When you configure data guard using OCI console, the default mode is set to maxprotection. been enabled on the database prior to the failover and there must be sufficient Oracle Data Guard helps you change the role of databases between primary and standby using either a switchover or failover operation. However, no additional data is applied on the standby database once you invoke the failover. occurred to the target standby database prior to disabling fast-start You must then re-create it from a copy of the new primary database and reenable it as described in How to Re-create and Reenable a Disabled Database. The word manual is used to contrast this type of failover with a fast-start failover (described in Fast-Start Failover). You can specify particular conditions for which a fast-start failover should occur using either Cloud Control or the DGMGRL ENABLE FAST_START FAILOVER CONDITION and DISABLE FAST_START FAILOVER CONDITION commands. Note that role changes to logical standby databases always result in physical standby database bystanders being disabled. Bystander standby databases that are not disabled by the broker after the switchover will continue operating in the state they were in before the switchover. You can upgrade the protection mode later, if necessary, as described in Setting the Protection Mode for Your Configuration. Regardless of the method you choose, the broker coordinates the role transition on all databases in the configuration. The foundation of FSFO is Data Guard - a primary and at least one standby. Note the use of "/@" to login using the wallet. ORACLE instance shut down. Steps for FAILOVER the Dataguard environment 1. It could optionally also be removed from the primary database if there is no intention to ever run this service on the current primary database. Reenabling Disabled Databases After a Role Change describes how to restore their viability as standby databases. Metadata for the fuzzy snapshot is stored in the flashback log itself. See the Oracle Maximum Availability Architecture technical briefs at: When setting the FastStartFailoverLagLimit configuration property, consider these tradeoffs between performance and potential data-loss: A low lag limit will minimize data loss but may impact the performance of the primary database. Performing failover : Step 1: Check Standby Database role. North_Sales is in the primary role. In this mode, the FastStartFailoverLagLimit configuration property is set to a non-zero value. They rely on Oracle Data Guard for high availability databases, with a standby database running in a different availability zone. (Snapshot standbys are not included in the table because they are not supported as fast-start failover targets.). The foundation of FSFO is Data Guard - a primary and at least one standby. Switchover to a logical standby database is disallowed when the configuration is operating in maximum protection mode. Initiate the failover on the standby database STAN: contains important information about the observer. The logs also contain other details about the actions that will be performed in case of a failover. In maximum protection mode, set the LogXptMode database property to SYNC (note that in maximum protection mode, a far sync instance cannot be used to ship redo to a standby). Waits for the target standby database to finish applying any unapplied redo data before stopping Redo Apply (if the target is a physical standby database) or SQL Apply (if the target is a logical standby database). If this occurs, run 'stop observer' and try again. ObserverPingRetry properties before Theoretically, this method can be used when a data guard failover occurred between the primary and standby database, but not a switchover. Whereas a switchover to a logical standby database will invalidate and disable all of the physical and snapshot standby databases in the configuration. Multiplexing SRLs merely adds unnecessary IO and can increase commit latency. The primary database was shut down without using the ABORT option. In short, the failover is the deformation of the production (primary) database and activating standby database as the primary. If you don't already have a Flash Recovery Area (FRA), you will need to create one for Flashback Database. observer immediately begins monitoring the status and connections to under the $DG_ADMIN directory. For example: The default value for the FastStartFailoverThreshold property is 30 seconds and the lowest possible value is 6 seconds. FSFO uses Flashback Database as part of the process of reinstating a failed primary as a standby. For example, if the old standby was a physical or snapshot standby, then the old primary must be re-created as a physical standby. PeopleSoft can be configured for Active Data Guard. If a group name is not specified, then SHOW OBSERVERS alone is also a valid command. For this reason, you should first issue this command on the target standby database. Because fast-start failover was not disabled on the target standby database, the observer may still attempt a fast-start failover to the target standby database should conditions warrant a failover. Monitor the environment to ensure the primary database is available. Observer sites monitor the fast-start failover environment. ZERO DATA LOSS: Fast-start failover is enabled with zero data loss. You can query the V$DATABASE view to verify that the observer is started and the configuration is ready for fast-start failover. Look for the desired data in the RAM.