data guard failover steps

The broker controls the rest of the switchover. 5. the observer was killed after the stall began, but before the failover timeout had elapsed). Stores files related to the observer and callout configuration. Transitions the target standby database into the primary database role, as follows: Changes the role of the database from standby to primary. Specifying Preferred Observers Based on Current Primary. The examples shown in this section do not necessarily show the specific attributes you might need to use in your own environment. In previous releases, OCI and ODP.NET clients receive FAN notifications via Oracle Advanced Queuing (AQ). By default, both files are stored in $ORACLE_HOME/dbs. They cannot be reinstated. See Oracle Data Guard Concepts and Administration for information about tuning the log apply rate for a physical standby database. Broker will set the primary to use asynchronous log transport by default. Once fast-start failover is enabled, the broker will ensure that fast-start failover Reinstatement is supported only after failover in a broker configuration. Data Guard Broker - Controls the creation and monitoring of Data Guard. specified by the ObserverPingInterval property. DGMGRL to manage multiple observers on multiple configurations. This is time, if all the sessions that are connected though the active services The price for this guarantee is increased commit latency ( log file sync waits). To proceed, you must first disable fast-start failover using the FORCE option, and then perform a manual failover. FSFO configurations in Maximum Performance mode may limit potential data loss by specifying the maximum allowable age of transactions that are lost during a failover. For information about enabling fast-start failover, see Enabling Fast-Start Failover. Updates the broker configuration file to record the change in roles. command is submitted successfully, the command-line prompt on the The word ALL cannot be used as a group name because it is a reserved keyword. You can customize fast-start failover setup for a specific application by using the DBMS_DG PL/SQL package. STOP OBSERVING, and SET In maximum availability mode, set the LogXptMode database property for both the primary and target standby databases to SYNC or FASTSYNC. primary database. The time interval specified by the FastStartFailoverThreshold property is ignored if the master observer detects that a user-configurable condition has occurred or if a fast-start failover has been requested by the DBMS_DG.INITIATE_FS_FAILOVER function. This results in the observer establishing a new connection to the primary database every 30 seconds. In this case, the observer cannot perform a fast-start failover even if conditions warrant a failover. 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). FastStartFailoverThreshold for reference information about the FastStartFailoverThreshold property. SQL> select name,open_mode,database_role from v$database; NAME OPEN_MODE DATABASE_ROLE --------- -------------------- ---------------- MYTEST MOUNTED PHYSICAL STANDBY Step 2: Apply the following command to finish database recovery. SQL> Select Database_role from v$Database; Oracle Data Guard Broker is a utility that can help you manage your Oracle Data Guard. The original primary database can now be configured as a standby. Stopping the observer does not disable fast-start failover. Group definition this section is optional. OBSERVE-ONLY: Fast-start failover is enabled in observe-only mode. After step 1 finishes, Switch the original physical standby db STAN to primary role; Manual failover to the fast-start failover target can be performed without receiving an acknowledgement from the observer. The subdirectories that DGMGRL creates under this directory will also have the If fast-start failover is already enabled, the The minimum value of ObserverPingInterval is 100 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. For Maximum Availability environments, change this to synchronous. For more details about managing redo transport services using database properties, see Managing Redo Transport Services. You need to consider all of the options at the time you are building your Oracle Data Guard configuration, including factors such as the characteristics of physical standbys versus logical standbys versus snapshot standbys, the network latency to your standby database sites, the computing capabilities at a future primary database site, and so on. Download Ebook Oracle 11g 12c Data Guard With Asm Lab Practice A Complete Hands On Lab Practice To Manage A Data Guard . These scripts must be in the same directory as the This If there is more than one registered observer, then this command returns an error; a name is required if there is more than one observer. 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. For each temporary table, verifying that temporary files associated with that table on the primary database also exist on the standby database. Clusterware agent that the failover completed, the Oracle Clusterware agent opens PDBs Starting with 10.2.0.4 (including all versions of 11g and later), Oracle provides the FastStartFailoverPmyShutdown Broker property that allows you to specify what the primary should do if it is still in a stalled state when the FSFO threshold timeout has elapsed. Follow the guidelines described in Choosing a Target Standby Database. For instance, you could log into the system running observer1 to stop observer2. If the target is a snapshot standby database, the broker first converts the database back to a physical standby and then starts Redo Apply to apply all the accumulated redo before completing the failover and opening the database as a primary database. Displays the current fast-start failover mode. A switchover to a physical standby database is preferable because all databases in the configuration will be available as standby databases to the new primary database after the switchover operation completes. 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. November 20, 2009. All other registered observers are considered to be backup observers. In If the primary database is an Oracle Real Application Clusters (Oracle RAC) database, the master observer will attempt to connect to one of the remaining primary instances. 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. Start the observer by running dgmgrl and logging in using SYS credentials. In the following example commands, a service named PAYROLL is configured to be active in the PRIMARY role on the primary database NORTH. Once the observer has initiated a fast-start failover, the primary database shuts down automatically. In addition to setting the configuration protection mode to maximum performance, you will also need to ensure that the LogXptMode database property for both the primary and target standby database is set to ASYNC. connection, or the database on which you issued the disable fast-start failover 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. Before enabling fast-start failover in data guard broker, the only required precondition is enabling Flashback Database. Logical standby databases that are disabled during failover can be reinstated. The simplest way to do this is to abort the primary. fsfo_postcallout are stored in the same location as 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). status before the crash. session. In maximum performance mode, the ability to automatically failover is restored In an Oracle Data Guard configuration, the SRVCTL -startoption for a standby database is always set to OPEN after a switchover. This may result in data loss. After fast-start failover is enabled and up to four observers are started, one observer is nominated as the master observer that continuously monitors the environment to ensure the primary database is available. Failing over the database won't do much good if applications and other database clients don't know where the primary went. Complete Failovers in Configurations Using Far Sync Instances. In a Managed Instance with multiple databases in Azure we can have high availability. 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. Only two databases, the primary and the failover target, can be in the FSFO configuration at any given time. Note that the value of the FastStartFailoverPmyShutdown configuration property must be FALSE for the primary to stall indefinitely under these conditions. The word manual is used to contrast this type of failover with a fast-start failover (described in Fast-Start Failover). File. If the FastStartFailoverPmyShutdown configuration property is set to TRUE, then the former primary database will have been automatically shut down and must be manually restarted before the master observer can attempt to reinstate it. fast-start failover has not occurred to the target standby database. Unlike ORLs, SRLs should be created with only one member per group. 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. post-callout script, and pre-callout success file for the broker This table describes the optional database properties that you can set. If the new primary database was a primary database in the past, and had block The Oracle Database 11g observer can make use of specific credentials, allowing the same wallet to be used for multiple observers with different SYS passwords. You must use the Oracle wallet to store the credentials for all broker configurations to be managed. Bounce your database and verify database name its open mode and its role: SQL> shutdown immediate; ORA-01109: database not open Database dismounted. Now it will return PRIMARY. 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. Default value is 10 miliseconds. It will return PHYSICAL STANDBY, operation: Example 6-1 Fast-start Failover Configuration Indexing is a mechanism by which the underlying data is mapped for faster retrieval. Data guard Configuration details:- Login in to Standby Server:- Step:1 Check the database role and open_mode Select name,open_mode,database_role from v$database; The new ConfigurationWideServiceName configuration property can be used to simplify setting up this connect identifier. In maximum availability mode, the behavior depends on the value of the See Reenabling Disabled Databases After a Role Change. The selected standby database that will be the fast-start failover target must receive redo directly from the primary database. A fast-start failover occurred because a user-configurable condition was detected or was requested by an application by calling the DBMS_DG.INITIATE_FS_FAILOVER function. The following paragraphs describe the supported availability modes. receives redo data from a far sync instance. After setting local_listener, register the database with the listener and verify the services have been registered. 11.2 rac servicefailover 2020-01-28 ORACLE ORACLE RAC/ASM RAC112. In the following example, a service named sales is configured to be active in the PHYSICAL_STANDBY role on the primary database NORTH. To issue commands and interact with the Make sure everything is working before moving on. If it's not, DGB will not allow the failover to continue until the DBA has manually resolved any discrepancies. To verify the readiness of the fast-start failover configuration, issue the DGMGRL SHOW CONFIGURATION VERBOSE command or the SHOW FAST_START FAILOVER command on the primary database. It's good practice to use separate listeners for application connections and Data Guard connections. 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. 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. Displays only on a logical standby database that has not yet completed loading a copy of the primary database's data dictionary. These FAN events can be used in the following ways: Applications can use FAN without programmatic changes if they use one of these Oracle integrated database clients: Oracle Database JDBC, Oracle Database Oracle Call Interface (OCI), Oracle Data Provider for .NET ( ODP.NET), or Universal Connection Pool for Java. As a result the observer may still initiate fast-start failover to the target standby database, if conditions warrant a failover. Issue the following SRVCTL commands: Now the correct services are running on the correct databases. You have done a failover to your Standby database so it becomes the new Primary. After a failover, the broker publishes Fast Application Notification (FAN) events. 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. Observers should be installed and run on a computer system that is separate from the primary and standby systems. To achieve 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. When a switchover is started, the primary and standby databases that are involved should have as small a redo lag as possible. Initiate the failover on the standby database STAN: It behaves similarly to START OBSERVING and STOP OBSERVING to operate on all the configurations defined in the observer configuration file. The values that indicate FSFO is ready for failover are listed below. In this example, there are 3 ORLs with a max group# of 3. Facebook:https://www.facebook.com/HariPrasathdba This page will not allow you to alter the protection mode. fsfocallout.ora and they have the required permissions. Any database that was disabled while multiple role changes were performed cannot be reinstated. RMAN also copies the spfile and password files and you can change the values for individual parameters. 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. A switchover guarantees no data loss and is typically done for planned maintenance of the primary system. 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. Open another prompt and connect to SQLPLUS: POTENTIAL DATA LOSS: Fast-start failover is enabled with some data loss. 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). If there is another standby database that is available for failover, you can perform a manual failover to that standby database after you first disable fast-start failover using the FORCE option on that standby database. instructions for the DGMGRL command-line interface. 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. The physical and snapshot standby databases will have to be re-created from a copy of the new primary database. For reliable startup, the initial connection should always be made to the primary. The other configurations that are not required but they might make your fast-start failover go smoothly. If that metadata is pushed out, Oracle can no longer find a fuzzy snapshot so it will not be able to flash back. are configured correctly. Step-B: Copy control file to temporary location on primary database. For each broker configuration on which one or more The VALIDATE FAST_START FAILOVER command can be used to validate a fast-start failover configuration and identify misconfigurations that prevent the initiation of fast-start failover. When restarting the databases, you may restart them in any order. The broker disables all of the physical and snapshot standby databases in the configuration. property. stored in the specified path using the default file names. to set the time taken to detect a failure on the primary database: Set the FastStartFailoverThreshold Do this prior to every failover test. It provides a way to quickly restore a database to a previous point in time or SCN using on-disk data structures called flashback logs. This is cleared on both when the reinstatement has been completed. Data Guard Switchover/failover to standby The standby database will be activated to serve as the primary database at some point in its life cycle. primary database must have network connectivity. If the Oracle Data Guard configuration is operating in maximum protection mode, the broker does not allow a switchover to occur to a logical standby database. When performing a switchover in a configuration whose standby databases are The observer is very lightweight, requiring few system resources. operation can be automated using callout scripts. The following is a sample observer configuration file: Since the broker configuration SALES consists of three databases, Boston, Chicago, and Dallas, with a CONNECT_ID of SALES_P, the SALES_P connect identifier must be defined such that it can reach any instance of any database within the configuration. 2. That process is shown here. What is true about data guard set up with fast-start failover (FSFO) in Oracle Cloud Infrastructure (OCI)? Whereas a switchover to a logical standby database will invalidate and disable all of the physical and snapshot standby databases in the configuration. Errors occurring for any other configuration members will not impede the switchover. There's a big difference between a system that's FSFO enabled and one that's FSFO ready. The default name for If it detects that Flashback Database was disabled, either manually, or automatically because Flashback Database discovered a problem, Broker signals "ORA-16827: Flashback Database is disabled". Create a pre-callout script, or a post-callout script, or both. In this example, the original primary data is called PRIM and the original standby database is called STAN. The following sections provide more information about the fast-start failover environment: When Fast-Start Failover Is Enabled and the Observer Is Running, Restrictions When Fast-Start Failover is Enabled, Shutting Down the Primary Database When Fast-Start Failover Is Enabled, Performing Manual Role Changes When Fast-Start Failover Is Enabled. If automatic reinstatement fails, the broker will log errors and the former primary database will remain in the mounted state. If you want to capture any logging generated by the observer, use the LOGFILE IS option on the START OBSERVER command, and ensure that the file name is unique. This list describes restrictions when fast-start failover is enabled. Metadata for the fuzzy snapshot is stored in the flashback log itself. Staff support, hardware and software, security (both software and site), network connections, and bandwidth should be equivalent at both sites. The same process should work for RAC environment as my colleague has . This exercises the configuration, but triggers failover differently than losing contact with the primary. This They must be re-created before they can serve as standby to the new primary database. Broker maintains these parameters by issuing ALTER SYSTEM commands as appropriate during role transitions, database startup/shutdown, and other events. 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. configuration file In 10g, a single wallet can be used for multiple observers, but they must all use the same SYS password. observer on ob1-host will be given priority over For example: Fast-start failover occurs if both the observer and the target standby database lose connection to the primary database for the period of time specified by the FastStartFailoverThreshold configuration property. This section describes how to stay on top of your FSFO environments. The services include switchover, switchback and failover. Use the SHOW CONFIGURATION BystandersFollowRoleChange command to see the value of this property. 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). FastStartFailoverLagLimit property. required permissions, fast-start failover callouts will fail. services. A normal shutdown prevents a fast-start failover until the primary database and standby database are connected and communicating again. The minimum value is 100 milliseconds. under the $DG_ADMIN directory. Databases that have been disabled after a role transition are not removed from the broker configuration, but they are no longer managed by the broker. FSFO uses Flashback Database as part of the process of reinstating a failed primary as a standby. enabling fast-start failover. To do this, use the SET ObserverConfigFile and SHOW ObserverConfigFile commands. When fast-start failover is disabled, no observer is called the master observer; all observers have the same functionality. Note that this does not guarantee no data will be lost. You must specify it every time you start a new DGMGRL client. Additionally, the new master observer is identified in the output shown for the SHOW FAST_START FAILOVER and SHOW OBSERVER commands. This walkthrough assumes that all ORLs and SRLs on the primary and standby databases are the same size. configuration property. If failover is not possible for some reason, then the master observer will continue checking whether the standby database is ready to fail over. callout directory. if the observer is not running, The master observer and the target standby database are inconsistent with regard to the current state of the broker configuration, If the protection mode is maximum availability or maximum protection and the target standby database was not synchronized with the primary database at the time the primary database failed, If the protection mode is maximum performance and the apply point of the target standby database lags the redo generation point of the primary database by more than the amount specified by the FastStartFailoverLagLimit configuration property at the time the primary database failed. Enable Active Data Guard for read-only workloads. multi-tenant environments Know the database downgrade steps in case the upgraded database isn't compatible with the environment Discover the features and benefits to the organization when it moves from the old database . Prepare the primary database in advance for its possible future role as a standby database in the context of the overall protection mode (see Managing Data Protection Modes). Displays when the primary and target standby databases are synchronized and the configuration is operating in maximum availability mode. If you cannot tolerate any loss of data, then ensure that the configuration protection mode is set to maximum availability or maximum protection.

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