data guard failover steps
Thus, the command-line prompt on the observer computer does not Fast-start failover can be used only in a broker configuration and can be configured only through DGMGRL or Cloud Control. When fast-start failover is enabled, the primary and standby randomly choose one of the registered observers to be the master. Set the ObserverPingInterval and Figure 6-1 shows the relationships between the primary database, target standby database, and observer during fast-start failover: Before Fast-Start Failover: Oracle Data Guard is operating in a steady state, with the primary database transmitting redo data to the target standby database and the observer monitoring the state of the entire configuration. The FastStartFailoverThreshold time interval starts when the observer first detects there might be a failure with the primary database. You can start the observer before or after you enable Create a pre-callout script, or a post-callout script, or both. After Fast-Start Failover: The fast-start failover has completed and the target standby database is running in the primary database role. Maximum availability SYNC or FASTSYNC or ASYNC, Maximum performance SYNC or FASTSYNC or A switchover guarantees no data loss and is typically done for planned maintenance of the primary system. If the designated fast-start failover target develops a problem and cannot be the target of a failover, then the broker automatically changes the fast-start failover target to one of the other candidate targets. There are two types of failover operations: Graceful or "no-data-loss" failover and Forced or "minimal-data-loss" failover. . failure on the primary database. The procedure for using RMAN to create a standby database is fully explained in Appendix F of Oracle Oracle Data Guard Concepts and Administration document (10g Rel 2 and 11g Rel 1). The following table summarizes which standby types are supported in which protection modes when fast-start failover is enabled. STOP OBSERVING [cfg_group_name] stops LOCAL observers running on this host (where this DGMGRL is running) for all broker configurations in a specified group. SQL> Select Database_role from v$Database; The following is an example of starting an observer as a background process: The START OBSERVER IN BACKGROUND command uses Oracle wallet to obtain credentials to log into the database server and register observers. 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 currently configured mode is maximum protection, Cloud Control will downgrade the mode to maximum availability. Disabling fast-start failover with the FORCE option when connected to the target standby database guarantees that fast-start failover will not occur. session. If this 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. 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. In a complete failover, it is also possible to failover to a standby database (terminal standby) that gets redo from another standby database (cascader). MASTEROBSERVERHOSTS, DGMGRL reports an error if the If reinstatement of a database fails, its status changes to ORA-16795: the standby database needs to be re-created. If errors occur during the disable operation, the broker returns an error message and stops the disable operation. In this example, there are 3 ORLs with a max group# of 3. The time interval starts when the observer first loses its connection to the primary database. Note that the broker does not use the properties to set up redo transport services and Redo Apply services until you actually switch over the primary database to the standby role. 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. During failover, bystanders "follow" the primary by default, flashing back and reapplying redo from the new primary as necessary. Create a script to automate FSFO failover initiation and use it as your standard method for standby flips. See theFlashback Database section above for information on storage requirements. The connect descriptor must contain the SERVICE_NAME parameter in either case. The failover was to a logical standby database. A failed ping is a ping to STANDBY> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY; This property cannot be used to prevent the primary database from shutting down if a fast-start failover occurred because a user configuration condition was detected or was requested by an application by calling the DBMS_DG.INITIATE_FS_FAILOVER function. DG_ADMIN environment variable is not set, the files are stored in If the observer is unable to regain a connection to the primary database within the specified time, and the target standby database is ready for fast-start failover, then fast-start failover ensues. A single-instance database must be registered with Oracle Restart in order to publish FAN events via ONS. Neither the primary database nor the logical standby database needs to be restarted after the switchover completes. environment variable to specify the default location for client-side broker files. Bystander standby databases may be disabled by the broker during the failover, and they must be reinstated or re-created before they can serve as standby databases to the new primary database. DGConnectIdentifier, "Scenario 9: Performing a Switchover Operation" for an example of using the VALIDATE DATABASE command to show a database's readiness to complete a role switchover, "Scenario 10: Performing a Manual Failover Operation" for an example of using the VALIDATE DATABASE command to show a database's readiness to complete a role failover. Now it will return PRIMARY. 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. configuration named ConfigurationSimpleName. In an immediate failover, it is also possible to failover to a standby database (terminal standby) that gets redo from another standby database (cascader). The ObserverReconnect configuration property specifies how often the observer establishes a new connection to the primary database. Its primary job is to perform a failover when conditions permit it to do so without violating the data durability constraints set by the DBA. To allow the database to register with the Data Guard listener, the listener endpoint must be added to the database's local_listener parameter. Instead, it allows an observer that is monitoring the configuration to initiate a fast-start failover should database conditions warrant a failover. Disabling fast-start failover does not stop the observer. When both databases have been restarted, you may restart the observer. If the former physical standby database was running with real-time query enabled, the new physical standby database will run with real-time query enabled. Client-side broker These are the actions the broker performs after you start a complete failover. 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. A complete failover is the recommended and default failover option. When performing a switchover in a configuration whose standby databases are alter database recover managed standby database finish; alter database activate standby database; Managed recovery process has been stopped between primary and standby database and standby becomes primary database. A fast-start failover to the target standby database fails. SET MASTEROBSERVER TO allows you to manually change the observer configuration file. Failover automation ensures a seamless transition from the primary database to a synchronized standby database in cases of failure, while ensuring database availability by replaying uncommitted in-flight transactions. observer on ob1-host will be given priority over alter database recover managed standby database cancel; Step:3 The below commands will help to bring up standby as primary. Switchover to a logical standby database is disallowed when the configuration is operating in maximum protection mode. You must use the Oracle wallet to store the credentials for all broker configurations to be managed. Flashback Database stores its logs in the Flash Recovery Area (FRA), so the FRA must be large enough to store at least 60 minutes of Flashback Database history. The application needs to catch this error and respond accordingly. In addition, a logical standby database may contain only a subset of the data present in the primary database. required permissions, the admin folder is created Figure 6-2 The Observer in the Fast-Start Failover Environment. A switch-over allows the primary database to switch roles with its standby database. configuration file exists. 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. Tags: Data Guard, Oracle. To proceed, you must first disable fast-start failover using the FORCE option, and then perform a manual failover. A switchover is a role reversal between the primary database and one of its standby databases. Updates the broker configuration file to record the change in roles. Verifies that the target standby database is enabled. connection, or the database on which you issued the disable fast-start failover In a separate terminal session, verify the configuration. This walkthrough uses Maximum Availability mode to achieve "zero data loss". If the 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. Displays if the standby database's redo applied point lags 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. If the failover target database is an Oracle RAC physical or snapshot standby database, the broker directs Oracle Clusterware to restart all instances that may have been shut down prior to the failover. Provides an automatic failover environment that For Active Oracle Data Guard, it will fail to open up a connection unless its in read-only mode. These facilities allow applications written to take advantage of them to receive asynchronous notification of database events, including role transitions. When you configure data guard using OCI console, the default mode is set to maxprotection. The target standby database when it does not have connectivity with the primary database, fast-start failover is disabled only on the target standby database. Oracle Data Guard with Fast-Start Failover (FSFO) can provide additional resiliency by setting up the broker on a separate machine. This can be avoided by first disabling fast-start failover with the FORCE option on the target standby. When running the START Prerequisites for Enabling Fast-Start Failover provides complete information about all of the fast-start failover and reinstatement requirements. Please contact us at contactus@smarttechways.com. The state file is locked when the observer is running to prevent multiple observers from using the same file. 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. The failover time is dependent upon whether the target standby database (physical or logical standby database) has applied all of the redo data it has received from the primary database. may allow the primary database to continue redo generation after If a non-zero value is specified for the Initiate reinstatement by mounting the database. ERROR: Unable to verify the graphical display setup. The command fails if the file does not exist. Use the SQL ALTER DATABASE MOVE DATAFILE command to rename or relocate an online data file on a physical standby that is a fast-start failover target if the standby is mounted, but not open. You can disable fast-start failover if necessary, by using the FORCE option. The targets are referred to as candidate targets. Switch-over steps: Step-A: Shutdown primary database: SQL> shut immediate; Database closed. There's a big difference between a system that's FSFO enabled and one that's FSFO ready. environment variable is set and the specified directory has the Es gratis registrarse y presentar tus propuestas laborales. Default value is 100 In addition, the database to be reinstated and the new 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. There are normally two situations when this operation will be performed: a planned outage for maintenance of the primary database or disaster recovery. ob2-host can be a master observer when The Appendix provides information oncreating a simple wrapper script to start the observer as a background process. 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). Oracle Data Guard Command-Line Interface Reference for more information about these broker commands. property. It automatically sets Data Guard related database initialization parameters on instance start and role transitions, starts apply services for standbys, and automates many of the administrative tasks associated with maintaining a Data Guard configuration. Issue the following commands on Primary database and Standby database to find out: 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. Example 6-2 Sample Observer Configuration File. If the database is managed by Oracle Clusterware, broker does not open any of the This nomination is noted in the observer log file and in the broker log file (drc*.log). The platform provides comprehensive services such as maintaining and monitoring databases to help the oracle databases in surviving during data corruption. Before stopping an observer, note the following: The observer does not stop immediately when you issue the STOP OBSERVER command. On Windows, the directory specified by the DG_ADMIN You can use this information to identify ahead of time any redo transport configurations that would be incorrect after a role change, including any standbys that will not receive redo because the RedoRoutes property was not configured correctly. Oracle Database 10g databases running versions prior to 10.2.0.4 will remain in a stalled state until aborted or signaled to remain the primary by the observer once connectivity has been restored. Aug 2022 - Present6 months. These STOP OBSERVING, and SET Errors occurring for any other configuration members will not impede the switchover. Only the observer can initiate FSFO failover. this script is run before the fast-start failover is initiated. In fact, failovers are so reliable, fast, and simple that switchovers become the exception rather than the rule. 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/. Examine the Broker configuration by logging into dgmgrl on the new primary. Unlike the primary / standby interconnect, where bandwidth and latency are determining performance factors, the observer requires very little network bandwidth and is not overly latency sensitive, allowing the it to be placed practically anywhere a reliable connection is available. the Steps To Congure Oracle 11g Data Guard Physical Standby associate that we give here and check . See Reenabling Disabled Databases After a Role Change. 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 environment that is guaranteed to either lose no data (when the See the Cloud Control online help for more information. Download Ebook Oracle 11g 12c Data Guard With Asm Lab Practice A Complete Hands On Lab Practice To Manage A Data Guard . If multiple observers have been started for the configuration, then be sure to specify the name of the observer whose environment is to be patched (STOP OBSERVER observer-name). restart the new physical standby database. This brings up the General Properties page that provides a Reinstate button. It is actually a low-footprint OCI client built into the DGMGRL CLI (Data Guard Broker Command Line Interface) and, like any other client, may be run on a different hardware platform than the database servers. files are stored in subdirectories of the DG_ADMIN directory. Instead, when broker notifies the Oracle 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. Manual failover gives you control over exactly when a failover occurs and to which target standby database. The master observer cannot connect to the target standby database, What Happens if the Observer Fails? You can use the broker's reinstate capability to make a failed primary database a viable standby database for the new primary. Logical standby databases that are disabled during failover can be reinstated. the primary and target standby databases. When restarting the databases, you may restart them in any order. DG_BROKER_START is set to TRUE and DG_BROKER_CONFIG_FILEn are set correctly SQL> sho parameter broker Notice that the former primary is now disabled. Time for action - using interfaces to monitor Data Guard; Other replication solutions and Data Guard; 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. When the observer loses its connection to the primary database for a period of time greater than that specified by the FastStartFailoverThreshold property, it attempts a failover to the standby database. failover to the target standby database. Notice that the terminal session appears to hang after starting the observer. Step:1 Check the database role and open_mode For example, if a physical standby database was in the APPLY-OFF state, it will remain in the APPLY-OFF state. This can be done regardless of whether the failover was done to a physical, logical, or snapshot standby database. If the PreferredObserverHosts property is set for the current pre-callout configuration script and post-callout configuration script. you need to make the primary database available, first confirm that a ObserverConfigFile is a DGMGRL session runtime property. environment variable must have exclusive permissions wherein it can be accessed only present, you must start the observer manually using the following SQL>select sequence#, applied from v$archived_log; In the following example, ObserverReconnect is set to 30 seconds. It has two parts in the following order: Configuration declaration this section is mandatory. Slightly less critical than making sure you've got a good primary is making sure the failed primary can be automatically reinstated. 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. This is For example: The default value for the FastStartFailoverThreshold property is 30 seconds and the lowest possible value is 6 seconds. For Oracle RAC databases, see Oracle Real Application Clusters Administration and Deployment Guide for more information about configuring database services with the SRVCTL utility. This configuration property establishes an acceptable limit, in seconds, that the standby is allowed to fall behind the primary in terms of redo applied, beyond which a fast-start failover will not be allowed. Automatic failover quickly and reliably fails over the standby Autonomous database to the primary database role, without requiring you to perform any manual steps. 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.