data guard failover steps

See the START OBSERVER Steps for FAILOVER the Dataguard environment The Be sure to include the Data Guard listener in the local_listeners database parameter. When the configuration has more than one registered observer, if the primary and target standby databases stay connected but the connection to the master observer is lost, then the broker tries to nominate a backup observer as the new master observer. Specifying the Observer Configuration File. If there are multiple observers, then only one of them is the master observer. The minimum value of ObserverPingInterval is 100 file (fsfo.dat). Many customers use Oracle Database deployed on Amazon Elastic Compute Cloud (Amazon EC2) to run their Oracle E-Business Suite applications. 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. If you cannot tolerate any loss of data, then ensure that the configuration protection mode is set to maximum availability or maximum protection. To start an observer, you must be able to log in to DGMGRL with an account that has It shuts down or stalls because it is likely a failover has occurred. configuration file, such as START OBSERVING, Only the observer can initiate FSFO failover. Overall Steps:-. to set the time taken to detect a failure on the primary database: Set the FastStartFailoverThreshold the location of the observer log file, and the location of the observer runtime data A running observer will follow the primary automatically after a role transition, but a newly (re)started observer won't start if the initial connection is to a down database or one with an out of date or corrupted Broker config file. The observer persistently maintains information about the fast-start failover configuration in a binary file created in the working directory where you started the observer. The string "NONAME" cannot be used as an observer name. 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. See Performing Manual Role Changes When Fast-Start Failover Is Enabled for more information. See Setting the Protection Mode for Your Configuration. See Sources of Diagnostic Information for details about the broker's drc* log files. After step 3 completes, you can open the new Primary database STAN: 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. 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. The default value is 30 seconds. A complete failover is the recommended and default failover option. the ObserverPingRetry and ObserverPingInterval properties to achieve Once the observer has initiated a fast-start failover, the primary database shuts down automatically. Step:6 After a failover, the original primary database can no longer participate in the Data Guard configuration. (Snapshot standbys are not included in the table because they are not supported as fast-start failover targets.). If a bystander standby database is not disabled by the broker during this failover, it will remain in the state it was in before the failover. When the process is complete, the database will be enabled as a standby database to the new primary database, and Cloud Control displays the Oracle Data Guard Overview page. This list describes conditions in which the broker cannot automatically reinstate the former primary database. This section will help you get started with creating a wrapper script to automatically start and restart the FSFO observer. START OBSERVING [cfg_group_name] starts a new observer for each broker configuration in the specified group. If you want the broker to skip this viability check of bystander standby databases during a complete failover, thus decreasing the overall failover time, set the BystandersFollowRoleChange configuration property to NONE. The advanced way is in the following article: Connect-Time Failover by a Dynamic Service Name. Issue the following SRVCTL commands: Now the correct services are running on the correct databases. SQL>STARTUP; You can perform a manual failover even if fast-start failover is enabled. That process is shown here. Fast-start failover will not occur unless all instances comprising the Oracle RAC primary database are perceived to have failed. The broker allows an immediate failover to proceed even if there are errors present on the standby database that you selected to participate in the failover. In such cases, the failed primary database is reinstated as a physical standby database. When performing a failover in a configuration whose standbys are all of the same type, choose the standby database that has the smallest transport lag. configuration property specifies how frequently the observer Multiplexing SRLs merely adds unnecessary IO and can increase commit latency. the preferred method for starting an observer. Write Engineering Change Proposal documentation and reports to request permission to install, replace . The reduced need for manual intervention can increase availability without increasing management costs. This is normal. 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. Restarts the new standby (former primary) database if the switchover occurs to a physical standby database, and Redo Apply begins applying redo data from the new primary database. Standby databases not involved in the switchover (known as bystander standby databases) continue operating in the state they were in before the switchover occurred and will automatically begin applying redo data received from the new primary database. For example, to determine if fast-start failover can occur, the FS_FAILOVER_STATUS column displays either SYNCHRONIZED or TARGET UNDER LAG LIMIT and the FS_FAILOVER_OBSERVER_PRESENT column displays YES for the target standby database. The v$database view has has columns specifically for monitoring FSFO status. If you do not want to use the default, you can define a specific group. SHOW OBSERVERS [FOR fg_group_name ] shows information about observers for all configurations in the specified group. The ObserverOverride configuration property, when set to TRUE, allows an automatic failover to occur when the observer has lost connectivity to the primary, even if the standby has a healthy connection to the primary. Fast-Start Failover allows Data Guard to automatically failover to a previously chosen standby database without requiring manual intervention to invoke the failover. After the patch has been successfully applied to all databases, take the following steps to enable fast-start failover and start the observer. The observe-only mode for fast-start failover enables you to test how fast-start failover will work in your environment. For example, if all your physical standbys are also unavailable, then failing over to a logical standby is your only choice. Once you have completed the switchover back to the original primary, you may then reenable the physical and snapshot standby databases since they are still viable standbys for the original primary database. You must determine which available standby databases should be targets for failover. Running a StatusReport on the primary should verify that the error is due to a missing observer. For example: The default value for the FastStartFailoverThreshold property is 30 seconds and the lowest possible value is 6 seconds. A failover may or may not result in data loss depending on the protection mode in effect at the time of the failover. Immediately after issuing command in step 2, shut down and restart the standby instance STAN: In this case, no attempt is made to transmit any unsent redo from the far sync instance to the target physical standby prior to converting the physical standby into a primary database. required permissions, fast-start failover callouts will fail. distance. 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. To start the observer with DGMGRL, issue the following Make sure the last redo data transmitted from the Primary database was applied on the standby database. Steps to Create a Physical Standby Databa se 3 -3 Preparing the Primary Database 3 -4 FORCE LOGGING . Note the use of "/@" to login using the wallet. Fast-start failover enables the Data Guard broker to rapidly and automatically failover to a previously chosen standby database without requiring manual intervention. Goal. Sign in to Azure Failover:- In case of worst situation with data guard primary database, or not available for production than we can activated standby database as a primary production database. If the WAIT option is included in the In case of worst situation with data guard primary database, or not available for production than we can activated standby database as a primary production database. 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. may allow the primary database to continue redo generation after The broker first converts the original primary database to run in the standby role. After a role change, the naming service can be updated with the new primary's address. mode when the fast-start failover target is a logical or physical standby database that Please contact us at [email protected]. SHOW ObserverConfigFile used to check the runtime property ObserverConfigFile. The configuration and database status report the same error messages as are returned when there is only one registered observer. These requirements are supplemental to those described in the documents previously referenced and in the following client-specific guides: Oracle Data Provider for .NET Developer's Guide for Microsoft Windows. If reinstatement of a database fails, its status changes to ORA-16795: the standby database needs to be re-created. Oracle recommends configuring Flashback Database on every database so that if failover occurs to a physical standby database, you can more easily reinstate any disabled standby databases. Reconnect within the time specified by the FastStartFailoverThreshold property. If one of these errors has occurred, follow the guidelines in "Resolving ORA-752 or ORA-600 [3020] During Standby Recovery" in My Oracle Support Note 1265884.1 before proceeding. You can create two callout configuration scripts, a What is true about Data Guard setup with fast-start failover? Immediate Failovers in Configurations Using Cascaded Standbys. Learn how to use Oracle Data Guard broker to manage databases during switchover and 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). For example: In the following example, assume the network between the primary database and the observer has failed. fast-start failover to the target standby database if conditions warrant a failover. SQL> Select Database_role from v$Database; (as it might in maximum availability and maximum performance modes). North_Sales is in the primary role. To see if your primary has already met a prerequisite, follow the instructions in the Verify section. The price for this guarantee is increased commit latency ( log file sync waits). You can use the broker's reinstate capability to make a failed primary database a viable standby database for the new primary. If a database must be re-created from a copy of the new primary database, it will have the following status: Re-create the standby database from a copy of the primary database and then reenable it, as described in How to Re-create and Reenable a Disabled Database. same permissions. Log into the new primary and verify that the changes made it across. Once Flashback Database has succeeded, the observer will convert the database to a standby, bounce it, and begin apply services. In an immediate failover, it is also possible to failover to a standby database (terminal standby) that gets redo from another standby database (cascader). configuration. FAN events are published using Oracle Notification Services (ONS) for all Oracle integrated database clients in Oracle Database 12c and later. specified by the ObserverPingInterval property. FastStartFailoverLagLimit property. The pre-callout script ensure that it has the required permissions. Broker changes database parameters during startup and role transitions via ALTER SYSTEM commands. This may take a few minutes. There can be up to four When DGMGRL starts, if the DG_ADMIN See the Cloud Control online help for more information. environment variable must have exclusive permissions wherein it can be accessed only Use the VALIDATE STATIC CONNECT IDENTIFIER command to ensure the static services have been configured correctly. See Directing a Fast-Start Failover From an Application). Standby databases that are disabled during switchover, manual failover, or fast-start failover will not be automatically reinstated. Because the broker performs the failover after converting the snapshot standby database to a physical standby database, it is likely that all standby databases in the configuration will still be available as standby databases to the new primary database after the failover operation completes. If the failover fails for any reason, it could leave the target standby database inoperable, regardless of whether the target standby database is ready to failover. You must provide a connect identifier, through which one or more databases in a specific broker configuration can be reached. When you execute commands that affect multiple observers, if you have not specified a name and location for the observer configuration file, then broker searches the current working directory for a file named observer.ora. milliseconds. PRIM>connect /@PRIM as sysdba If the database is not enabled, you will not be able to perform a failover to this database. 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. The following table summarizes which standby types are supported in which protection modes when fast-start failover is enabled. For more information, see SET MASTEROBSERVER TO. The command SHOW OBSERVER provides detailed information about registered observers. Verify the primary database instance is open. The word manual is used to contrast this type of failover with a fast-start failover (described in Fast-Start Failover). In order to maintain separation of Broker and non-Broker activity, a second static service is recommended. 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. It is then started and stopped on the primary database. Unlike ORLs, SRLs should be created with only one member per group. 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). 8.2 Private Cloud Appliance and . Be aware that if you issue the following manual commands on either of those databases, then both the SALESRO and SALESRW services would be started on the databases regardless of what you may have earlier specified with the SRVCTL -role qualifier. 11.2 rac servicefailover 2020-01-28 ORACLE ORACLE RAC/ASM RAC112. this script is run before the fast-start failover is initiated. A complete failover also attempts to avoid disabling any standby databases that were not the target of the failover, so that they may continue serving as standby databases to the new primary database. ORACLE instance shut down. It uses these databases as a copy of the . In cases where In PDBs. Look for the desired data in the RAM. In the following example commands, a service named PAYROLL is configured to be active in the PRIMARY role on the primary database NORTH. commands. Event notification and database connection failover support is available to database clients connected to local database services when a broker-managed failover occurs. You can use Cloud Control or DGMGRL, to perform either a complete (recommended) or an immediate failover. Reinstate the original primary database to act as a standby database in the new configuration. PRIM> ALTER DATABASE COMMIT TO SWITCHOVER TO PHYSICAL STANDBY WITH SESSION SHUTDOWN; Create a wallet and set the default username and password to the database's SYSDBA credentials (usually SYS). maximum availability and maximum performance modes, to avoid a In Oracle RAC configurations, the Inaccessible Logfile and Stuck Archiver health conditions may only be applicable to a single instance. Oracle also provides Fast Application Notification (FAN) for OCI clients and Fast Connect Failover for JDBC clients. SQL> Select Database_role from v$Database; This is This 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. Now we will see a step-by-step approach to perform a switchover between the primary and the logical standby database: . STANDBY>connect /@STAN as sysdba The only exception to this is failovers to snapshot standby databases. If the standby database's redo applied point is within that many seconds of the primary database's redo generation point, a fast-start failover will be allowed. This section describes how to configure and verify each prerequisite. 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. If fast-start failover is Automatic failover quickly and reliably fails over the standby Autonomous database to the primary database role, without requiring you to perform any manual steps. You can customize fast-start failover setup for a specific application by using the DBMS_DG PL/SQL package. 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. The syntax for the optional definition of a broker configuration group is: The group definition section is optional. On Linux/Unix, the directory specified by the DG_ADMIN environment 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. If the failover target is a logical standby database, the original primary database and all physical and snapshot standby databases in the configuration will be disabled. on ob3-host and ob4-host will not is guaranteed to lose no more than the amount of To see the specific parameter, use the "show database StatusReport" command. However, there may be exceptions to the recommendation to choose a physical standby database as the target standby database. ASYNC. If the specified log file is not accessible, or the LOGFILE IS option is not used, then the observer output is sent to standard output. the SYSDG or SYSDBA privilege. (See Disabling Fast-Start Failover for important considerations when using the FORCE option.). Stops Redo Apply or SQL Apply on the standby database immediately, without waiting until all available redo data has been applied. The ObserverReconnect configuration property specifies how often the observer establishes a new connection to the primary database. 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. That is, if the observer is connected to any instance in the Oracle RAC, all instances will show a value of YES. 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. The commands that can be executed for a group of configurations (as declared in an observer configuration file) are as follows. callout configuration scripts fsfo_precallout and After FSFO is enabled, Broker will continue to check that Flashback Database is enabled during health checks. If you expect the network to be disconnected for a long time and Use the Cloud Control Fast-Start Failover wizard or the DGMGRL ENABLE FAST_START FAILOVER command to enable fast-start failover. Do not attempt to reinstate the old primary database if an ORA-752 or ORA-600 [3020] error has occurred at the failover target. After setting local_listener, register the database with the listener and verify the services have been registered. 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). A single-instance database must be registered with Oracle Restart in order to publish FAN events via ONS. If the database is managed by Oracle Clusterware, broker does not open any pluggable 4. However, re-enabling Flashback Database will require a bounce since the database must be mounted and not open. With increased latency comes decreased throughput; however, in some cases the difference in throughput may be made up by increasing parallelism. 1. When enabling fast-start failover, the broker verifies that the property indicates an existing standby. Rather, fast-start failover will be enabled in accordance with the current protection mode. In these sample commands, the ellipse () signifies any other add service options you wish to supply. However, you do have the option of specifying a name and location for the observer configuration file. must ping the primary database. the observer was killed after the stall began, but before the failover timeout had elapsed). Broker checks to see if Flashback Database is enabled on the primary and failover targets when FSFO is enabled. The following example displays the contents of the fast-start failover If the credentials cannot be obtained, then the attempted command fails (but only for the broker configuration whose credentials have not been obtained). Enabling fast-start failover in a configuration operating in maximum performance mode provides better overall performance on the primary database because redo data is sent asynchronously to the target standby database. 12c Dataguard, In The command SHOW FAST_START FAILOVER shows a list of registered observers and indicates which one is the master. Data Guard Broker - Controls the creation and monitoring of Data Guard. Each group that you define must have at least one broker configuration. Start the observer by running dgmgrl and logging in using SYS credentials. This list describes restrictions when fast-start failover is enabled. When using Maximum Availability mode, consider lowering this to reduce the time commits block when the standby becomes unavailable. 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. Ensure SPFILE is used SQL> sho parameter spfile 2. 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. Figure 6-2 The Observer in the Fast-Start Failover Environment. ERROR: Unable to verify the graphical display setup. Twitter:https://twitter.com/hariprasathdba, In 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. using the same SYS credentials you used when you connected to the 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. Use broker configuration properties to set the time taken to detect a It behaves similarly to START OBSERVING and STOP OBSERVING to operate on all the configurations defined in the observer configuration file. WAIT option, broker waits for the amount of For example: Ordinarily the observer connects once to the primary and does not attempt to reconnect unless the connection has failed. 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. 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. This is the recommended method for disabling fast-start failover. files include the observer configuration file (observer.ora), observer log Fast-start failover quickly and reliably fails over the target standby database to the primary database role, without requiring you to perform any manual steps to invoke the failover. Change the failover target to the standby being switched over to, Change the failover target to the desired standby. Group definition this section is optional. You can disable fast-start failover if necessary, by using the FORCE option. 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. All Data Guard environments should enable force logging at the database level in order to guard against nologging tablespaces from being added. This is cleared on both when the reinstatement has been completed. SHOW CONFIGURATION VERBOSE, or SHOW OBSERVER Now your old standby database is become primary database, it is highly recommended to consider immediate full backup of primary database.

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