data guard failover steps

There are two types of failover operations: Graceful or "no-data-loss" failover and Forced or "minimal-data-loss" failover. To stop a specific observer when there are multiple registered observers running, issue the following command: You can log into DGMGRL from any machine to stop an observer. When a primary loses contact with both the failover target and the observer simultaneously, it enters a "stalled" state (v$database.fs_failover_status = 'STALLED') and any sessions still connected to the primary will block on commit. primary database must have network connectivity. Use the oraenv script provided by Oracle. post-callout script, and pre-callout success file for the broker The walkthrough begins with a single database that will become the primary of a Data Guard configuration. A single-instance database must be registered with Oracle Restart in order to publish FAN events via ONS. Now it will return PRIMARY. A broker configuration can belong to multiple groups. Then, on the Fast-Start Failover Configure page, select the standby database that should be the target of a failover. DG_BROKER_START is set to TRUE and DG_BROKER_CONFIG_FILEn are set correctly SQL> sho parameter broker To allow the master observer to automatically reinstate the former primary database, the database must be started and mounted. This can be avoided by first disabling fast-start failover with the FORCE option on the target standby. A manual failover is already in progress. Note: Data Guard requires dedicated server connections for proper operation. Permissions Required by the DG_ADMIN Directory. 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. After the broker receives the STOP OBSERVER request, the request is passed to the observer the next time the observer contacts the broker, and the observer then stops itself. See Enabling Fast-Start Failover for more information. Disabling fast-start failover with the FORCE option when connected to the target standby database guarantees that fast-start failover will not occur. ZERO DATA LOSS: Fast-start failover is enabled with zero data loss. 1,000,000 block changes on a small set of blocks generates less Flashback Database history than 1,000,000 changes on a larger set of blocks. Configure the protection mode. To verify this change, again query the Database_role column of V$DATABASE. Fast-start failover is enabled, but this standby database is not the target of the fast-start failover. create the directory specified by the DG_ADMIN environment variable and In fact, failovers are so reliable, fast, and simple that switchovers become the exception rather than the rule. Subsequent changes to the same block during the same snapshot are not recorded. Change the failover target to the standby being switched over to, Change the failover target to the desired standby. On the Oracle Data Guard Overview page, click Database must be reinstated. Contains the observer runtime data file for the broker Any database that was disabled while multiple role changes were performed cannot be reinstated. Each observer is identified by a name that you supply when you issue the START OBSERVER command. If the observer finds that the database is no longer the primary, it will attempt to reinstate it as the failover target standby. FSFO uses Flashback Database as part of the process of reinstating a failed primary as a standby. You can manage observers through either the Oracle Data Guard Overview pages in Cloud Control or using DGMGRL commands. Opens the new primary database in read/write mode. 1. See START OBSERVER IN BACKGROUND for more information Using the db_unique_name of each database as the Oracle Net alias is simple and intuitive. This can be done regardless of whether the failover was done to a physical, logical, or snapshot standby database. You can upgrade the protection mode later, if necessary, as described in Setting the Protection Mode for Your Configuration. The default 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. The real test of the configuration is a successful role transition in both directions with both switchover and FSFO failover. When fast-start failover is enabled, the broker determines if a failover is necessary and initiates the failover to the current target standby database automatically, with no need for manual intervention. 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. Step 4: Enable Fast-Start Failover Now we are ready to enable FSFO: DGMGRL> enable fast_start failover; Enabled in Zero Data Loss Mode. Always try to perform a complete failover first unless redo apply has stopped at the failover target due to an ORA-752 or ORA-600 [3020] error. This file OBSERVE-ONLY: Fast-start failover is enabled in observe-only mode. lag is less than or equal to the value specified by the An application should use caution when calling the DBMS_DG.INITIATE_FS_FAILOVER function because the observer will initiate failover, if at all possible. Written by authors well-known for their talent with RAC, Pro Oracle Database 11g RAC on Linux . In maximum availability mode, set the LogXptMode database property for both the primary and target standby databases to SYNC or FASTSYNC. Stop the observer using the DGMGRL STOP OBSERVER command. Application Continuity is supported for Oracle Data Guard switchovers to physical standby databases. The following conditions apply when multiple observers are registered for one configuration: When fast-start failover is enabled, one of the observers is the master observer. In previous releases, OCI and ODP.NET clients receive FAN notifications via Oracle Advanced Queuing (AQ). The required attributes vary depending on your configuration (including whether your environment is Oracle RAC-based or single-instance). 3. Careful consideration should be given before enabling fast-start failover for either of these conditions because doing so will supersede availability options provided by Oracle Clusterware. Read-Only Standby and Active Data Guard 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. FSFO is a feature of Broker which records information about the failover target, how long to wait after a failure before triggering a failover, and other FSFO specific properties. FastStartFailoverThreshold for reference information about the FastStartFailoverThreshold property. usually within three seconds if fast-start failover is enabled. In cases where 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. SQL>STARTUP; 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. 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. Specifying Preferred Observers Based on Current Primary. If no value is specified for the If reinstatement of a database fails, its status changes to ORA-16795: the standby database needs to be re-created. Overall Steps:-. Broker checks to see if Flashback Database is enabled on the primary and failover targets when FSFO is enabled. 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. DNS CNAME) that always resolves to the primary. FastStart Failover Ensues: Disaster strikes the primary database and its network connections to both the observer and the target standby database are lost. We'll start with switchovers. Then, on the Fast-Start Failover Change Mode page, click Enabled. The new primary database starts transmitting redo data to the new standby database. Switching over to a logical standby database results in the snapshot and physical standby databases in the broker configuration being disabled by the broker, making these databases no longer viable as standby databases. The broker automatically reenables the database as part of reinstating it. Only two databases, the primary and the failover target, can be in the FSFO configuration at any given time. fast-start failover to the target standby database if conditions warrant a failover. Manual failover to the fast-start failover target can be performed without receiving an acknowledgement from the observer. Use Broker's "show configuration" command to determine FSFO status and the "show database statusreport" command to drill down for details if Broker reports a problem. milliseconds. FastStartFailoverLagLimit property. return until you issue the STOP OBSERVER command SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY; 3. Example 6-2 Sample Observer Configuration File. Controlfile is permanently damaged because of a disk failure. Step-by-step instructions for manual reinstatement are described in Reenabling Disabled Databases After a Role Change. Once Flashback Database has succeeded, the observer will convert the database to a standby, bounce it, and begin apply services. They must be re-created before they can serve as standby to the new primary database. The default name for SET MASTEROBSERVER TO allows you to manually change the observer configuration file. Verify the primary database instance is open. data (in seconds) specified by the 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. session. The drain_timeout is specified in the SRVCTL This article - the seventh in this ongoing . There is no impact on your current configuration or on applications. callout directory. database's redo generation point by more than the value specified by the Updates the broker configuration file to record the change in roles. An observer process is integrated in the DGMGRL client-side component of the broker and typically runs on a different computer from the primary or standby databases and from the computer where you manage the broker configuration. This is called failover. A switchover is a role reversal between the primary database and one of its standby databases. databases (PDBs) on any of the instances. receives redo data from a far sync instance. Immediate Failovers in Configurations Using Far Sync Instances. On the new primary database STAN, perform a SWITCH LOGFILE to start sending redo data to the standby database PRIM. To stop an observer currently designated as the master observer, first issue the SET MASTEROBSERVER command to designate a different observer as master observer. However failing over to a snapshot standby database will require more time because the broker must first convert it back to a physical standby database. observer immediately begins monitoring the status and connections to The broker selects a target standby based on the order they are specified in the property. You can also query the V$FS_FAILOVER_STATS view to display statistics about fast-start failover occurring on the system. The subcommands for this verb include start, stop, setMaster, show, and delete_alternate_observer. Starts redo transport services to begin transmitting redo data to all bystander standby databases that were not disabled. Table 6-3 FS_FAILOVER_OBSERVER_PRESENT Column of the V$DATABASE View, The master observer is currently connected to the local database, The master observer is not connected to the local database. Tags: Data Guard, Oracle. After you click the Reinstate button, Cloud Control begins reinstating the database. We can always fail over to it or have it happen automatically if for some reason the primary Managed Instance has [] In the restore stage, Flashback Database restores the database to a point prior to the standby_became_primary_scn using the before-image blocks in the Flashback Database logs. You might, for instance, use this to allow the observer to monitor the databases using the same connect identifiers as the client applications. *PATCH v5 0/6] Add Toshiba Visconti Video Input Interface driver @ 2023-01-11 2:24 Yuji Ishikawa 2023-01-11 2:24 ` [PATCH v5 1/6] dt-bindings: media: platform: visconti: Add Toshiba Visconti Video Input Interface bindings Yuji Ishikawa ` (5 more replies) 0 siblings, 6 replies; 42+ messages in thread From: Yuji Ishikawa @ 2023-01-11 . Execute the following on primary database NORTH: Execute the following on the physical standby database SOUTH: If the broker now performs a switchover or failover, it automatically starts the SALES service on the correct database, based on the database's role. orapwd file=$ORACLE_HOME/dbs/orapw$ORACLE_SID. files to automate tasks that must be performed before and after a fast-start failover When you are experiencing network disconnections and you issue the DISABLE FAST_START FAILOVER FORCE command on the primary database or a standby database that does not have connectivity with the primary database, fast-start failover may not be disabled for all databases in the broker configuration. Clusterware: The broker notifies Oracle Clusterware to stop active Broker will set the primary to use asynchronous log transport by default. Broker will validate the configuration, set parameters on both databases, and start managed recovery. It is also supported for fast-start failover to physical standbys in maximum availability data protection mode. The connect-identifier is a TNS alias defined in tnsnames.ora through which all instances of all databases in this Data Guard broker configuration can be reached. The ObserverOverride and ObserverReconnect properties allow you additional control over the connection to the primary. Goal. In this case, only observers on ob1-host and This configuration property causes the former primary database to be automatically reinstated if a fast-start failover was initiated because the primary database was either isolated or had crashed. database is in the primary role. Setting this property to 'TRUE' (the default) causes the primary to self-terminate. Step:6 Verify the target standby database is ready for failover. exit. The act of switching roles should be a well-planned activity. occurred to the target standby database prior to disabling fast-start What is true about data guard set up with fast-start failover (FSFO) in Oracle Cloud Infrastructure (OCI)? Provides an automatic failover 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. $DG_ADMIN directory. Then set the configuration protection mode to maximum availability. Note: Many of the Broker database properties correspond to database spfile parameters. Learn how your comment data is processed. ORACLE instance shut down. You can use the SHOW CONFIGURATION WHEN PRIMARY IS command to show the redo transport configuration (based on each member's setting of the RedoRoutes property) that would be in effect if the specified database were the primary database. (Note: 11.1.0.7 adds the StaticConnectIdentifier Broker database property to allow you to specify a different service name.) See Choosing a Target Standby Database for helpful advice. Note that the value of the FastStartFailoverPmyShutdown configuration property must be FALSE for the primary to stall indefinitely under these conditions. WAIT option, broker waits for the amount of The minimum value is 100 milliseconds. The current primary database must have its LogXptMode property set accordingly and must have standby redo logs configured. There are normally two situations when this operation will be performed: a planned outage for maintenance of the primary database or disaster recovery. If clients are already configured to automatically time out and reconnect if they don't get a response from the database, a simple but effective approach is to use a network alias (e.g. After the patch has been successfully applied to all databases, take the following steps to enable fast-start failover and start the observer. 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. See Sources of Diagnostic Information for details about the broker's drc* log files. If the master observer detects an availability problem with the primary database, then it typically attempts to reconnect to the primary database within the time specified by the FastStartFailoverThreshold configuration property. The service can be started on the physical standby only after the redo generated by starting the service has been applied. In Oracle RAC configurations, the Inaccessible Logfile and Stuck Archiver health conditions may only be applicable to a single instance. the SYSDG or SYSDBA privilege. If they are isolated from each other, then you must first disable fast-start failover by using the FORCE option, and then stop the observer. Determining a Database's Readiness to Change Roles. 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. Stores the observer runtime data file and observer configuration file in PRIM> ALTER DATABASE COMMIT TO SWITCHOVER TO PHYSICAL STANDBY WITH SESSION SHUTDOWN; The master observer never waits for the threshold to expire to perform a fast-start failover in the following situations: If the master observer determines that any of the user-configurable conditions has been detected, then it attempts a fast-start failover. 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). Broker keeps its configuration details in flat file. To change the FastStartFailoverTarget property to point to a different standby database, disable fast-start failover, set the FastStartFailoverTarget property, and reenable fast-start failover. These Your email address will not be published. The commands that can be executed for a group of configurations (as declared in an observer configuration file) are as follows. There can be up to four file also declares broker configurations and defines configuration Fast-start failover will not be attempted for the other types of database shutdown (NORMAL, IMMEDIATE, TRANSACTIONAL). change tracking enabled, broker enables block change tracking on the new Oracle Data Guard work on two database roles Primary and Standby. 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 . The former primary database is disabled. Determine the number and size of the Online Redo Log files (ORLs). If the primary database can be mounted, it may be possible to flush any unsent redo data from the primary database to the target standby database using the ALTER SYSTEM FLUSH REDO SQL statement. Switchover and Manual Failover for more information about switchovers and manual failovers, respectively. Steps for FAILOVER the Dataguard environment 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. 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. LGWR is unable to write to any member of the log group because on an I/O error. Note the following points about the observe-only mode: The primary database can enter UNSYNC or LAGGING state without an acknowledgement from the observer or target standby. Installing and starting an observer is an integral part of using fast-start failover and is described in detail in the following sections: Oracle Data Guard Installation explains that you can either install only the Oracle Client Administrator or you can install the complete Oracle Database Enterprise Edition or Personal Edition on the observer system. RMAN will copy the spfile from the primary, so this init.ora file is only needed during the first phase of the duplication. 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. 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. By default, the observer creates this file in the current working directory when it is started and names the file fsfo.dat. For Fast Connection Failover (FCF) to occur, a client must be able to locate the new primary database after a failover. may allow the primary database to continue redo generation after For each temporary table, verifying that temporary files associated with that table on the primary database also exist on the standby database. The My Oracle Support note 1625597.1 at http://support.oracle.com for information about compatibility requirements between the observer and DGMGRL, Starting Multiple Observers on a Data Guard Broker Configuration. The observer configuration file is a text file and the syntax to define observers and groups is similar to that used in the listener.ora or tnsnames.ora files. PDBs. You cannot perform a switchover to a snapshot standby database unless you first convert it back to a physical standby database. See the Cloud Control online help for more information. SQL>SHUTDOWN IMMEDIATE; Regardless of the method you choose, the broker coordinates the role transition on all databases in the configuration. If client-side ONS configuration is used, the client-side ONS configuration file must specify the hostname and port of the ONS daemon(s) of the primary database and each standby database. The log file name is specified with the LOGFILE IS option of the START OBSERVER command. Writing the wrapper itself and the means to determine when to execute it are up to you. The broker controls the rest of the switchover. However, if the standby has had contact from the primary within the period of time specified by the FastStartFailoverThreshold property, the standby prevents the failover attempt. This can be compared to performing an RMAN restore of the datafiles from a backup taken prior to the specified SCN, but is much faster. the names of the scripts created in the previous step. SQL> Select Database_role from v$Database; This configuration property causes the primary database to shut down if fast-start failover is enabled and V$DATABASE.FS_FAILOVER_STATUS indicates the primary has been STALLED for longer than FastStartFailoverThreshold seconds.