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. lower detection times for primary database failures. The observer does not attempt to reinstate the former primary database. A switchover guarantees no data loss and is typically done for planned maintenance of the primary system. The previous examples dealt with setting up only one service on a database. A switchover is a role reversal between the primary database and one of its standby databases. The FORCE option disables fast-start failover on the database to which you are connected even when errors occur. In this case fast-start failover cannot occur because the databases are not ready to failover. directory. broker configuration, you must connect through another DGMGRL client Otherwise, they must be re-created from a copy of the new primary database. Maximum Availability mode uses synchronous redo transfer and FSFO imposes the additional requirement that the redo is recorded in the standby redo log (SRL) of the target standby (AFFIRM option of log_archive_dest_ n). Add an entry to the oratab file for the standby, db1:/u01/app/oracle/product/11.1.0/db_1:Y. When you select a standby database to be the next primary database after a switchover or a failover, there are several factors to consider. become the master observer. You can upgrade the protection mode later, if necessary, as described in Setting the Protection Mode for Your Configuration. OBSERVE-ONLY: Fast-start failover is enabled in observe-only mode. Starts redo transport services to begin transmitting redo data to all bystander standby databases that were not disabled. Make some new changes and verify that they are preserved after failover. Automatic failover quickly and reliably fails over the standby Autonomous database to the primary database role, without requiring you to perform any manual steps. Group definition this section is optional. The service is then configured to be active in the PRIMARY role on the standby database SOUTH, so that it will be active on that database after a role transition. These facilities allow applications written to take advantage of them to receive asynchronous notification of database events, including role transitions. If local_listener is already in use, add the Data Guard listener to the list. Then, on the Failover Confirmation page, click Yes to invoke the default Complete failover option. SQL> Select Database_role from v$Database; Oracle Data Guard can switch a standby database to the primary role in case a production database becomes unavailable due to . Managed recovery process has been stopped between primary and standby database and standby becomes primary database. Set the ObserverPingInterval and 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. Alternatively, use the RedoRoutes property to configure the redo transport mode for the target standby and the database currently in the primary role. This property specifies the amount of data, in seconds, that the target standby database can lag behind the primary database in terms of redo applied. During a complete failover, the broker performs the failover steps described in How the Broker Performs a Complete Failover Operation. An existing connection which is already closed from the database side would throw an error. Ensure that the required permissions are granted to the DG_ADMIN After a failover, a bystander will not automatically become the new failover target. prolonged stall, either the observer or target standby database property. The current primary database must have its LogXptMode property set accordingly and must have standby redo logs configured. The guide makes few assumptions about your existing environment and includes examples for creating a physical standby database and Data Guard Broker configuration. You must manually re-create the database as a standby database and then reenable it. Check the database role,open_mode in standby server. Enable Fast-Start Failover Using Cloud Control. 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. The FS_FAILOVER_STATUS column in the V$DATABASE view for the target standby database displays a reason why fast-start failover cannot occur. The broker allows the switchover to proceed as long as there are no errors for the primary database and the standby database that you selected to participate in the switchover operation. ObserverPingRetry configuration properties. configuration file exists. The primary database was shut down without using the ABORT option. The foundation of FSFO is Data Guard - a primary and at least one standby. Application Continuity is an Oracle Database feature that enables rapid and nondisruptive replays of requests against the database after a recoverable error that made the database session unavailable. Other members of the configuration will receive redo from the designated redo source based on the new primary. Each observer has its own log file. Follow the guidelines described in Choosing a Target Standby Database. See the START OBSERVER If the observer is unable to regain a connection to the primary database within the specified time, then the observer begins a fast-start failover provided the standby database is ready to fail over. If it's not, DGB will not allow the failover to continue until the DBA has manually resolved any discrepancies. broker does not allow the primary database to commit transactions until it has regained If the service has been configured to start automatically (-policy AUTOMATIC), then the service will automatically start only after a database role change. 1. Make sure that your OS environment on the standby is setup. 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 fast-start failover succeeds, if a post-callout script is specified in the fast-start Monitoring flashback database history and reacting when it drops below 30 minutes will save you time and improve availability. If a single-instance primary database (either Oracle RAC or non-Oracle RAC), or if all instances of an Oracle RAC primary database are shut down with the ABORT option, the observer attempts a fast-start failover. However, there may be exceptions to the recommendation to choose a physical standby database as the target standby database. If both the observer and designated standby database lose connectivity with the primary database for longer than the number of seconds specified by the FastStartFailoverThreshold configuration property, the observer will initiate a fast-start failover to the standby database. The ObserverOverride and ObserverReconnect properties allow you additional control over the connection to the primary. After a switchover completes, the broker preserves the overall Oracle Data Guard protection mode as part of the switchover process by keeping the protection mode at the same protection level (maximum protection, maximum availability, or maximum performance) it was at before the switchover. Default value is 100 If there is only one observer, then it is considered to be the master observer. Metadata for the fuzzy snapshot is stored in the flashback log itself. the primary database that failed or took longer than the time DG BrokerDG BrokerData Guard BrokerOracleDGRMAN Duplicate . Controlfile is permanently damaged because of a disk failure. files to automate tasks that must be performed before and after a fast-start failover The failed primary database requires reinstatement as a new standby database to the new primary. The broker continuously monitors for all sessions that are connected That is, if the observer is connected to any instance in the Oracle RAC, all instances will show a value of YES. In this example, there are 3 ORLs with a max group# of 3. This section lists the steps the master observer takes to determine if a fast-start failover is needed and then to perform one, if necessary. 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. orapwd file=$ORACLE_HOME/dbs/orapw$ORACLE_SID. What is true about Data Guard setup with fast-start failover? This will signal the observer to initiate failover after the FSFO threshold timeout has been reached (default is 30 seconds). In maximum availability mode, set the LogXptMode database property for both the primary and target standby databases to SYNC or FASTSYNC. Now it will return PRIMARY. 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. To see if your primary has already met a prerequisite, follow the instructions in the Verify section. For information about enabling fast-start failover, see Enabling Fast-Start Failover. See Oracle Data Guard Concepts and Administration for more information on using the ALTER SYSTEM FLUSH REDO statement. These commands can be issued from the DGMGRL command line, but it is not necessary to log on prior to using them. If the PreferredObserverHosts property is set for the current 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. stored in the specified path using the default file names. Oracle Real Application Clusters Administration and Deployment Guide for more information about configuring FAN, FCF, and ONS on an Oracle Real Application Clusters (Oracle RAC) database. DGMGRL. expires. distance. Enabling fast-start failover does not trigger a failover. operation can be automated using callout scripts. Were sorry. This article - the seventh in this ongoing . Add the wallet location and override to sqlnet.ora. specified, the file is stored in an appropriate directory under the broker's When DGMGRL starts, if the DG_ADMIN SQL>STARTUP; Switch-over steps: Step-A: Shutdown primary database: SQL> shut immediate; Database closed. Let's run the command on the primary database to validate if the environments are ready for the role transition : JITPRD> alter database switchover to JITSDB verify; alter database switchover to JITSDB verify * ERROR at line 1: ORA-16475: succeeded with warnings, check alert log for more details Use the VALIDATE STATIC CONNECT IDENTIFIER command to ensure the static services have been configured correctly. Stores files related to the observer and callout configuration. This database property is used to specify how the observer should connect to and monitor the primary and standby database. 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. Some properties have changed between those releases. on ob3-host and ob4-host will not 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. 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 allows the appropriate Data Guard services, such as redo transport or redo apply, to be started when the database is restarted later for any reason. Note that role changes to logical standby databases always result in physical standby database bystanders being disabled. This is the recommended method for disabling fast-start failover. To start an immediate failover, use the DGMGRL FAILOVER TO database-name IMMEDIATE command. See Installing and Starting the Observer. Because fast-start failover was not disabled on the target standby database, the observer may still attempt a fast-start failover to the target standby database should conditions warrant a failover. Enabling Fast-Start Failover Task 1: Determine Which of the Available Standby Databases is the Best Target for the Failover, Enabling Fast-Start Failover Task 2: Specify Target Standbys with the FastStartFailoverTarget Configuration Property, Enabling Fast-Start Failover Task 3: Determine the Protection Mode You Want, Enabling Fast-Start Failover Task 4: Set the FastStartFailoverThreshold Configuration Property, Enabling Fast-Start Failover Task 5: Set Other Properties Related to Fast-Start Failover (Optional), Enabling Fast-Start Failover Task 6: Enable Additional Fast-Start Failover Conditions (Optional), Enabling Fast-Start Failover Task 7: Using DGMGRL or Cloud Control, Enabling Fast-Start Failover Task 8: Start the Observer, Enabling Fast-Start Failover Task 9: Verify the Fast-Start Failover Environment. Displays only on a logical standby database that has not yet completed loading a copy of the primary database's data dictionary. 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). 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. crash, data in this file can be used to restart the observer to the If there is only one registered observer, then it works in the same manner that a single observer worked prior to the advent of multiple observers in Oracle Database 12c Release 2 (12.2.0.1). As a result, there is no guarantee that the observer will not perform a fast-start failover to the target standby database if the observer determines that conditions warrant a failover. Instead, when broker notifies the Oracle 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. must ping the primary database. Note that this does not guarantee no data will be lost. The role change is directed to the same standby database that was specified for the FastStartFailoverTarget database property on the primary database. Logical standby databases that are disabled during failover can be reinstated. You want to conduct a manual failover to any standby database in the configuration (for example, because a failure occurred on the primary database at a time when the primary and target standby database were not ready to failover). select name,open_mode,database_role from v$database; Note: Create a pre-callout script, or a post-callout script, or both. An application should use caution when calling the DBMS_DG.INITIATE_FS_FAILOVER function because the observer will initiate failover, if at all possible. Learn how your comment data is processed. To avoid the overhead of recording every change to every block, Flashback Database takes a "fuzzy" snapshot every 30 minutes and only records the before-image block upon its first change since the last snapshot. We want the observer to be able to automatically reinstate the former primary as a standby after our failover tests, so before each test, make sure that Flashback Database has at least 30 minutes of history. The failover was to a logical standby database. If you initiated a complete failover and it fails, you might need to use immediate failover. Disabling fast-start failover without the FORCE option can succeed only if the database on which the command is issued has a network connection with the primary database and if the primary database and target standby database have a network connection. Sets up redo transport from the new primary to the other members of the configuration, Starts Redo Apply services on the new standby, Ensures the other standbys in the broker configuration are viable to the new primary, Integrates with Oracle Clusterware and Oracle Global Data Services (GDS) to ensure that the proper services are started after a role change. There can be up to four The configuration and database status report the same error messages as are returned when there is only one registered observer. Verify the standby database instance is mounted. Your email address will not be published. Opens the new primary database in read/write mode. 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. The broker selects a target based on the order in which they are specified on the FaststartFailoverTarget property. In Maximum Availability mode, FSFO guarantees that no transaction that has received a commit acknowledgment will be lost during a failover. If reinstatement of a database fails, its status changes to ORA-16795: the standby database needs to be re-created. Any apply delay must be removed before beginning a switchover. failover with the FORCE option on the primary database. In fact, failovers are so reliable, fast, and simple that switchovers become the exception rather than the rule. Sign in to Azure Learn how to use Oracle Data Guard broker to manage databases during switchover and failover. performance protection mode with fast-start failover. 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 word ALL cannot be used as a group name because it is a reserved keyword. In this case, the primary database stalls and prevents any further transactions from 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. Once the observer is started, you cannot change the file's name and location. In order to accommodate all load conditions, Oracle recommends having at least one more SRL group than the number of ORL groups of the same size. All Data Guard environments should enable force logging at the database level in order to guard against nologging tablespaces from being added. 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. an alias of the broker configuration name. ob2-host can be a master observer when By default, a fast-start failover is done when both the observer and the standby cannot reach the primary after the configured time threshold (FastStartFailoverThreshold) has passed. is guaranteed to lose no more than the amount of To configure fast-start failover in observe-only mode: Fast-start failover will not be triggered if the primary or standby database is shut down normally. 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). It's generally a good idea to store the state file in a directory associated with the database to avoid locking issues when running multiple observers on the same host. second. To maintain a viable disaster-recovery solution in the event of another disaster, you may need to perform additional steps. To override this behavior and allow a fast-start failover to occur if the observer is unable to contact the primary for more than FastStartFailoverThreshold seconds, set the ObserverOverride property to TRUE. 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. . 2. fsfocallout.ora and they have the required permissions. If the target standby database is ready for failover, then the master observer immediately directs the target standby database to fail over to the primary database role. SQL Apply on all other bystander standby databases automatically begin applying redo data received from the new primary database. The same process should work for RAC environment as my colleague has . After the restart, Redo Apply begins applying redo data from the new primary Now test FSFO failover back to the original primary. Facebook:https://www.facebook.com/HariPrasathdba
Vermont State Police Incident Reports,
Is Yellowbrick Legit,
Golf Club Of Avon Membership Cost,
Articles D
