data guard failover steps

It has two parts in the following order: Configuration declaration this section is mandatory. It doesn't consider how much of that redo has been applied. If you do not want to use the default, you can define a specific group. It uses these databases as a copy of the . STANDBY> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY; The role change is directed to the same standby database that was specified for the FastStartFailoverTarget database property on the primary database. Steps for FAILOVER the Dataguard environment directory does not have the required permissions. Immediate: No additional data is applied on the standby database, resulting in a data-loss . What is true about data guard set up with fast-start failover (FSFO) in Oracle Cloud Infrastructure (OCI)? This can be done regardless of whether the failover was done to a physical, logical, or snapshot standby database. For switchovers, understanding all of the factors can simplify the choice of which standby database to consider as your new primary database. Reinstatement will have to be accomplished by other means (manual or scripted Broker commands). It is possible to manually perform a completer failover to a standby database that receives redo data from a far sync instance. The time interval starts when the observer first loses its connection to the primary database. Provides an automatic failover environment 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). Oracle Data Guard Broker is a utility that can help you manage your Oracle Data Guard. START OBSERVING [cfg_group_name] starts a new observer for each broker configuration in the specified group. Restore - Flashback Database restores the datafiles to the closest snapshot prior to the specified SCN. A failover may or may not result in data loss depending on the protection mode in effect at the time of the failover. 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. For example, if the old standby was a physical or snapshot standby, then the old primary must be re-created as a physical standby. the observer on ob2-host to become the master The broker allows the failover to proceed as long as there are no errors for the standby database that you selected to participate in the failover. standby database, host, or network failure, etc.). observers for a single Data Guard configuration. Restart the database to the mounted state, Use Cloud Control or DGMGRL to reinstate the database. 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). For reliable startup, the initial connection should always be made to the primary. files include the observer configuration file (observer.ora), observer log This file contains connect identifiers to both the primary and the target standby databases. This is typically done for planned maintenance of the primary system. In 10g, a single wallet can be used for multiple observers, but they must all use the same SYS password. The command SHOW FAST_START FAILOVER shows a list of registered observers and indicates which one is the master. The original primary database will be restarted as a part of the switchover operation. Initiate the failover on the standby database STAN: SQL>connect /@STAN as sysdba SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE FINISH; SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY; 2. The original primary database can now be configured as a standby. Tasks that must be performed before and after a fast-start failover Determining a Database's Readiness to Change Roles. Problems with automatic reinstatement are frequently due to misconfiguration, so let's look at this in a bit more detail. 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. Simply use DISABLE FAST_START FAILOVER. This database property is used to specify how the observer should connect to and monitor the primary and standby database. For more details about managing redo transport services using database properties, see Managing Redo Transport Services. Tailing the alert logs on the primary and standby is a good way to watch Broker in action and get familiar with how it performs various tasks. Sign in to Azure If the former primary database cannot be reinstated automatically, you can manually reinstate it using either the DGMGRL REINSTATE command or Cloud Control. Your email address will not be published. This list describes restrictions when fast-start failover is enabled. If there is only one standby database in the configuration, you can skip this step and continue with Task 3. Oracle Database 11g adds the ObserverConnectIdentifier database property to the Broker configuration, allowing you to specify a connect identifier for the observer to use for monitoring the primary and failover target. They can all be done at the same time in a single bounce. In this case, the observer cannot perform a fast-start failover even if conditions warrant a failover. You cannot create the standby DB system in a different AD from the primary DB system. In fact, failovers are so reliable, fast, and simple that switchovers become the exception rather than the rule. The observe-only mode for fast-start failover enables you to test how fast-start failover will work in your environment. This Subsequent changes to the same block during the same snapshot are not recorded. Only two databases, the primary and the failover target, can be in the FSFO configuration at any given time. The FS_FAILOVER_OBSERVER_PRESENT column, which indicates whether the observer is running and actively pinging the database. This property allows you to specify a priority ordered Starting with Oracle Database Release 21c, use the DG_ADMIN an alias of the broker configuration name. The reduced need for manual intervention can increase availability without increasing management costs. Among many benefits of using this utility, I highlight that while using it, it will not need manual intervention to recover the databases or eventually a switchover in case the primary database becomes unavailable. For example, if all your physical standbys are also unavailable, then failing over to a logical standby is your only choice. variable must have read, write, and execute permissions for the directory owner 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. 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. Then, click Continue to proceed to the next page. Open another prompt and connect to SQLPLUS: In these sample commands, the ellipse () signifies any other add service options you wish to supply. The playground: All standbys other than the failover target are considered bystanders (v$database.fs_failover_status = 'BYSTANDER'). Reinstatement of the failed primary database as a new standby database failed. select name,open_mode,database_role from v$database; Note: Steps that require the primary to be in a mounted (not open) state are grouped together in the section below entitled Steps Requiring a Bounce of the Primary. When you configure data guard using OCI console, the default mode is set to maxprotection. The foundation of FSFO is Data Guard - a primary and at least one standby. These facilities allow applications written to take advantage of them to receive asynchronous notification of database events, including role transitions. Sets up redo transport from the new primary to the other members of the configuration, Starts Redo Apply services on the new standby, Ensures the other standbys in the broker configuration are viable to the new primary, Integrates with Oracle Clusterware and Oracle Global Data Services (GDS) to ensure that the proper services are started after a role change. If fast-start failover is When you configure data guard using OCI console, the default mode is set to maxprotection. The observer host is 'observer.demo.org'. Figure 6-2 The Observer in the Fast-Start Failover Environment. environment that is guaranteed to either lose no data (when the In an environment where there are multiple observers configured, stopping the master observer is not allowed unless it is the last running observer. See Installing and Starting the Observer. However the target can receive redo from a far sync instance.). specified, the file is stored in an appropriate directory under the broker's For example: Scenario 6: Enabling Fast-Start Failover and Starting the Observer. Examine the Broker configuration by logging into dgmgrl on the new primary. There are many examples, and Ritesh Chhajer offers this example of doing a Data Guard switchover using dgmgrl: 1. The act of switching roles should be a well-planned activity. Reinstatement is supported only after failover in a broker configuration. 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. Displays if the standby database's redo applied point does not lag the primary database's redo generation point by more than the number of seconds specified by the FastStartFailoverLagLimit configuration property and the configuration is operating in maximum performance mode. It is possible to manually perform an immediate failover to a standby database that receives redo data from a far sync instance. If failover is not possible for some reason, then the master observer will continue checking whether the standby database is ready to fail over. to set the time taken to detect a failure on the primary database: Set the FastStartFailoverThreshold Displays only on the target standby database when either the primary or target standby database was shut down in a controlled fashion (using the NORMAL, IMMEDIATE, or TRANSACTIONAL, options, but not the ABORT option). FSFO uses Flashback Database as part of the process of reinstating a failed primary as a standby. If a fast-start failover was initiated because the primary database had crashed or lost connectivity with the master observer and target standby database, then the master observer automatically attempts to reinstate the former primary database as a standby database, if the FastStartFailoverAutoReinstate configuration property is set to TRUE. Oracle Real Application Clusters Administration and Deployment Guide for information about Application Continuity, The broker simplifies switchovers and failovers by allowing you to invoke them using a single key click in Oracle Enterprise Manager Cloud Control (Cloud Control) or a single command in the DGMGRL command-line interface (referred to in this documentation as, Ensure that the standby database you choose to be the target of fast-start failover has its, Oracle Data Guard Concepts and Administration. 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. A good method to determine Flashback Database storage requirements is to enable Flashback Database and observe the amount of storage it uses during several peak loads. You can switch back to the original Primary database later by performing another switch over. On Linux/Unix, the directory specified by the DG_ADMIN environment To stop the observer when fast-start failover is disabled, the primary database must be running. Any unsent redo data residing on the far sync instance is transmitted to the target physical standby prior to converting the physical standby into a primary database. The behavior of the broker if the master observer fails depends on whether the broker configuration has one observer or multiple observers. If errors occur during the disable operation, the broker returns an error message and stops the disable operation. The pre-callout script Alternatively, you can query the V$DATABASE view on the target standby database. This table describes the optional database properties that you can set. Now that we know switchovers work, it's time to test failovers. Chapter 9 of the Data Guard Broker documentation (10g and 11g) contains a description of each property. Instead, the old primary database must be re-created as a standby from a backup of the new primary using the procedure described in How to Re-create and Reenable a Disabled Database. Switches roles between the primary and standby databases. environment variable must have exclusive permissions wherein it can be accessed only Issue the DISABLE FAST_START FAILOVER command or the DISABLE FAST_START FAILOVER FORCE command. 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/. Fast-Start Failover allows Data Guard to automatically failover to a previously chosen standby database without requiring manual intervention to invoke the failover. the Steps To Congure Oracle 11g Data Guard Physical Standby associate that we give here and check . Since a fast-start failover (automatic failover) could become a false failover when the observer or the standby database cannot connect to the primary database within a specific time, which may cost the database to lose some transactions followed by reinstating or recreating the standby database (the former primary database). You The NetTimeout property specifies the number of seconds LGWR will block waiting for acknowledgment from the standby in synchronous mode before considering the connection lost (corresponds to the NET_TIMEOUT option of log_archive_dest_n). Observers continuously monitor the fast-start failover environment to ensure the primary database is available (described in When Fast-Start Failover Is Enabled and the Observer Is Running). You want to prevent fast-start failover from occurring because the primary database will resume service soon. A failover may or may not result in data loss depending on the protection mode in effect at the time of the failover. 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. 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. 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. miliseconds. observer as a foreground process. This page will not allow you to alter the protection mode. Oracle Data Guard work on two database roles Primary and Standby. The following assumes that the standby host has been setup according to Oracle's recommendations and that the operating system, accounts, security, resource limits, directory structure, etc. For each temporary table, verifying that temporary files associated with that table on the primary database also exist on the standby database. Dataguard Switchover Using DGMGRL A switchover is a role reversal between the primary database and one of its standby databases. 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. This exercises the configuration, but triggers failover differently than losing contact with the primary. stored in the specified path using the default file names. Initiate the failover on the standby database STAN: Oracle Data Guard configuration with DGMGRL. Each observer has its own log file. The standby can be physical or logical and there can be multiple standbys, but only one of the standbys can be the failover target at any given time. 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. For example: Ordinarily the observer connects once to the primary and does not attempt to reconnect unless the connection has failed. This feature enables RMAN to duplicate an existing database over the network without requiring a backup to disk or tape. As described in theFlashback Database section, Flashback Database takes place in two stages: a restore stage and a media recovery stage. Change Standby to Primary Database. (If there are other conditions, unique to an application, that would warrant a fast-start failover then the application can be set up to call the DBMS_DG.INITIATE_FS_FAILOVER function and start a fast-start failover immediately should any of those conditions occur. Applications can initiate FSFO failover directly using the DBMS_DG.INITIATE_FS_FAILOVER procedure with an optional message text that will be displayed in the observer log and the primary's alert log. In this case, only observers on ob1-host and To start an observer, you must be able to log in to DGMGRL with an account that has The steps in this section describe the tasks involved to perform a manual failover. Specifying Preferred Observers Based on Current Primary. ConfigurationSimpleName represents The FastStartFailoverThreshold time interval starts when the observer first detects there might be a failure with the primary database. fsfocallout.ora. However, fast-start failover cannot occur when the target standby database is in an unobserved state. MASTEROBSERVERHOSTS, DGMGRL reports an error if the In cases where If Flashback Database was enabled on the primary database.If not, the whole setup process must be followed, but this time using the original primary server as the standby. Required fields are marked *. Controlfile is permanently damaged because of a disk failure. Although redo transfer is synchronous, Maximum Availability mode allows the primary to remain available if the standby database becomes unavailable for any reason (e.g. You may failover to a snapshot standby database. The default You must use the Oracle wallet to store the credentials for all broker configurations to be managed. The name of the callout configuration scripts is specified in Create a trigger based on the, Oracle Database PL/SQL Language Reference, Choosing a Target Standby Database for Switchover, Choosing a Target Standby Database for Failover, Scenario 9: Performing a Switchover Operation, Scenario 10: Performing a Manual Failover Operation, Database Service Configuration Requirements, Troubleshooting Problems During a Switchover Operation, How the Broker Performs a Complete Failover Operation, How the Broker Performs an Immediate Failover Operation, Setting the Protection Mode for Your Configuration, Scenario 7: Enabling Fast-Start Failover When a Far Sync Instance Is In Use, Description of "Figure 6-1 Relationship of Primary and Standby Databases and the Observer", Enabling Fast-Start Failover Task 7: Configure Actions Before and After Fast-start Failover (Optional), Directing a Fast-Start Failover From an Application, Fast-start Failover Callout Configuration Files, Oracle Data Guard Command-Line Interface Reference, Description of "Figure 6-2 The Observer in the Fast-Start Failover Environment", Oracle Enterprise Manager Command Line Interface. In the following example, ObserverReconnect is set to 30 seconds. Enable Active Data Guard for read-only workloads. In the event of a If the value is zero, the standby must A failover to a logical standby database requires that all physical and snapshot standby databases be re-created from a copy of the new primary database after the failover completes. After you click the Reinstate button, Cloud Control begins reinstating the database. A complete failover is the recommended and default failover option. alter system set standby_file_management=auto; This parameter must be set before the primary can be opened in Maximum Availability mode. Application Continuity is an Oracle Database feature that enables rapid and nondisruptive replays of requests against the database after a recoverable error that made the database session unavailable. Broker will set the primary to use asynchronous log transport by default. 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. With FSFO enabled, Broker expects to find an observer, which we haven't started yet, so if you verify the at this point with 'show configuration', Broker will report a warning (if it doesn't, give it a minute to discover that the observer isn't there). ORACLE instance shut down. FSFO builds upon a number of other Oracle technologies and features such as Data Guard, Flashback Database, and Data Guard Broker. The broker interacts with Oracle Clusterware or Oracle Restart to ensure that the appropriate database services are active and that the appropriate FAN events are published after a role change. 3. They rely on Oracle Data Guard for high availability databases, with a standby database running in a different availability zone. For Fast Connection Failover (FCF) to occur, a client must be able to locate the new primary database after a failover. Create a unique connect alias for each database. An observer is a separate OCI client-side component that run on a different computer from the primary and standby databases and monitors the availability of the primary database. ORACLE instance shut down. If a single-instance primary database (either Oracle RAC or non-Oracle RAC), or if all instances of an Oracle RAC primary database fail, the observer attempts a fast-start failover. Monitoring flashback database history and reacting when it drops below 30 minutes will save you time and improve availability. On the Oracle Data Guard Overview page, click Database must be reinstated. (For example, if the DBMS_LOGSTDBY.SKIP procedure was used to specify which database operations done on the primary database will not be applied to the logical standby database.). By default, the observer will initiate failover to the target standby if and only if ALL of the following are true: Oracle Database 11g Rel 1 introduced user configurable failover conditions that can trigger the observer to initiate failover immediately. During a switchover, the primary database transitions to a standby role, and the standby database transitions to the primary role. STOP OBSERVING, and SET The OberverPingRetry property specifies the number of Here's a one-liner observer startup for *nix. (Note: 11.1.0.7 adds the StaticConnectIdentifier Broker database property to allow you to specify a different service name.) you need to make the primary database available, first confirm that a To install Oracle Data Guard, you need to create two Azure VMs on the same availability set: The primary VM (myVM1) has a running Oracle instance.