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. 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. See Choosing a Target Standby Database for helpful advice. 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. The list is empty by default. To determine if the configuration is ready for fast-start failover to occur, issue the DGMGRL SHOW DATABASE command, or query the V$DATABASE view on either the primary or target standby databases. These conditions are described in the following table: Dictionary corruption of a critical database. Credentials Required for Access to Broker Configurations. fsfocallout.ora and they have the required permissions. The terminal session will appear to hang at this point. Enabling fast-start failover and starting an observer process involves the following tasks. performance protection mode with fast-start failover. there is a lost network connection, be aware that the observer may attempt a 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. To avoid problems due to timing variations, values less than 60 minutes are not recommended and values of 30 or less virtually guarantee Flashback Database failure. The observer host is 'observer.demo.org'. That process is shown here. name of the observer log file is If you initiated a complete failover and it fails, you might need to use immediate failover. This document only talks about switchover involving physical standby database. To see Manual Switch Over Manual SwitchOver in Oracle To see Manual Fail Over Manual Failover in Data Guard With Oracle Data Guard [] Broker checks to see if Flashback Database is enabled on the primary and failover targets when FSFO is enabled. 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. With increased latency comes decreased throughput; however, in some cases the difference in throughput may be made up by increasing parallelism. Once the primary database regains connectivity with the target standby database, fast-start failover will be disabled for all the databases in the configuration. Stores files related to the observer and callout configuration. Keep this trigger as simple and reliable as possible, limiting it to only what is absolutely necessary at the moment of role transition, since any failures at this point may affect availability. Simply use DISABLE FAST_START FAILOVER. Only the master observer can coordinate fast-start failover with Data Guard broker. To maintain a viable disaster-recovery solution in the event of another disaster, you may need to perform additional steps. These are the guidelines for choosing a target standby database. configuration named ConfigurationSimpleName. Bounce your database and verify database name its open mode and its role: SQL> shutdown immediate; ORA-01109: database not open Database dismounted. Any database that was disabled while multiple role changes were performed cannot be reinstated. observers are registered, a directory named These are the actions the broker performs after you start a switchover. It has two parts in the following order: Configuration declaration this section is mandatory. To perform specified actions before or after a fast-start failover The primary database can be opened even if there is no acknowledgement from the observer or target standby. RMAN also copies the spfile and password files and you can change the values for individual parameters. Broker changes database parameters during startup and role transitions via ALTER SYSTEM commands. Fast-start failover will not occur unless all instances comprising the Oracle RAC primary database are perceived to have failed. The example uses the FROM ACTIVE DATABASE clause introduced in 11g that allows RMAN to create a standby database by copying the primary across the network without the need to store the backup files on disk or tape. Initiate the switchover on the primary database PRIM: property. 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. The following paragraphs describe the supported availability modes. Note that this does not guarantee no data will be lost. the names of the scripts created in the previous step. SUSPENDED is cleared when connectivity with the primary database is restored. On Linux/Unix, the directory specified by the DG_ADMIN environment If automatic reinstatement fails, the broker will log errors and the former primary database will remain in the mounted state. A far sync instance or Zero Data Loss Recovery Appliance is not a database and therefore cannot be the target of a role transition. Starting Multiple Observers On a Single Host. observer name, host, whether it is the master observer, when it became the master 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. In such cases, the failed primary database is reinstated as a physical standby database. ORACLE instance shut down. Es gratis registrarse y presentar tus propuestas laborales. After setting local_listener, register the database with the listener and verify the services have been registered. The SRVCTL utility does not automatically take the database role into account, so any time you start a service manually, you must specify the name(s) of the service you want started. The Learn how to use Oracle Data Guard broker to manage databases during switchover and failover. However, no additional data is applied on the standby database once you invoke the failover. The default value is 30 seconds and the lowest possible value is 5 seconds. directory does not have the required permissions. configuration file, such as START OBSERVING, Reinstatement will have to be accomplished by other means (manual or scripted Broker commands). If you are not using Oracle Clusterware or Oracle Restart, then you must create static service names so that the observer can automatically restart a database as part of reinstatement. Failing over the database won't do much good if applications and other database clients don't know where the primary went. In addition, the database to be reinstated and the new OBSERVE-ONLY: Fast-start failover is enabled in observe-only mode. The word ALL cannot be used as a group name because it is a reserved keyword. The steps in this section describe the tasks involved to perform a manual failover. A switchover is a role reversal between the primary database and one of its standby databases. the current working directory. See Setting the Protection Mode for Your Configuration. SHOW OBSERVERS [FOR fg_group_name ] shows information about observers for all configurations in the specified group. If it reconnects to the primary database before the standby agrees to fail over, then the master observer will stop attempting to initiate a fast-start failover. This list describes how the overall Oracle Data Guard protection mode is handled after a manual failover (complete or immediate). When running the START Now we will see a step-by-step approach to perform a switchover between the primary and the logical standby database: . Broker will validate the configuration, set parameters on both databases, and start managed recovery. Valid values are >= 10. It behaves similarly to START OBSERVING and STOP OBSERVING to operate on all the configurations defined in the observer configuration file. Each observer has its own log file. Select name,open_mode,database_role from v$database; Step:2 Cancel the MRP process commands. 2. You can create two callout configuration scripts, a It is also supported for fast-start failover to physical standbys in maximum availability data protection mode. For example: The following example shows the fast-start failover information for the DRSolution configuration: The following SHOW OBSERVER command displays information about multiple observers in the DRSolution broker configuration. Now let's test switchover in the other direction. Run the RMAN utility and connect to the target (primary) and auxiliary (new standby). If the broker performs a switchover or failover, then it starts the service SALESRW or SALESRO based on the current role of the database. A failover may or may not result in data loss depending on the protection mode in effect at the time of the failover. 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. Example 6-2 Sample Observer Configuration File. Starting the Observer Using Cloud Control. However, failover is attempted if the ObserverOverride configuration property is set to TRUE. milliseconds and that of ObserverRetryCount is 10. Nothing will ruin your day faster than finding out that the standby the observer just failed over to is 12 hours behind in applying redo. On the Oracle Data Guard Overview page next to the Fast-Start Failover status field, click Disabled to invoke the Fast-Start Failover page. The broker first converts the original primary database to run in the standby role. 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. To move the observer to another computer: There is no need to disable fast-start failover when you move the observer. 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. LinkedIn:https://www.linkedin.com/in/hari-prasath-aa65bb19/ Although redo transfer is synchronous, Maximum Availability mode allows the primary to remain available if the standby database becomes unavailable for any reason (e.g. By default, the observer uses the same connect identifiers used by Data Guard for redo transfer and information exchange between the primary and standby ( DGConnectIdentifier in Oracle Database 11g, InitialConnectIdentifier in Oracle Database 10g). FSFO uses Flashback Database as part of the process of reinstating a failed primary as a standby. Reinstate the former primary database as a new standby database. POTENTIAL DATA LOSS: Fast-start failover is enabled with some data loss. Note: Many of the Broker database properties correspond to database spfile parameters. broker configuration, you must connect through another DGMGRL client Client-side broker See Installing and Starting the Observer. 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. There are two types of failover operations: Graceful or "no-data-loss" failover and Forced or "minimal-data-loss" failover. observer immediately begins monitoring the status and connections to (If there are other conditions, unique to an application, that would warrant a fast-start failover then the application can be set up to call the DBMS_DG.INITIATE_FS_FAILOVER function and start a fast-start failover immediately should any of those conditions occur. See FastStartFailoverTarget for more information about this property. To enable fast-start failover with DGMGRL, issue the ENABLE FAST_START FAILOVER command while connected to any database in the broker configuration, including on the observer computer. If Flashback Database was enabled on the primary database.If not, the whole setup process must be followed, but this time using the original primary server as the standby. This directory is created when you run the This file is stored in the 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). 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). When both databases have been restarted, you may restart the observer. Manual failover to the fast-start failover target can be performed without receiving an acknowledgement from the observer. 8.2 Private Cloud Appliance and . value of the FastStartFailoverThreshold property. They must be re-created from a copy of the new primary database. Download Ebook Oracle 11g 12c Data Guard With Asm Lab Practice A Complete Hands On Lab Practice To Manage A Data Guard . It automatically recovers the maximum amount of redo data for the protection mode the configuration is operating in. For example, if the limit specified is 30 seconds (the default), FSFO guarantees that all transactions that committed prior to 30 seconds ago are preserved during failover. Bystanders are part of the Data Guard configuration, but not part of the FSFO configuration. primary database. If the primary and target standby databases do not have network connectivity or if the database to which you are connected does not have network connectivity with the primary database, consider using DISABLE FAST_START FAILOVER with the FORCE option. All Data Guard environments require the use of a password file in order to allow the databases to connect to each other. Use the callout configuration file and script Make some new changes and verify that they are preserved after failover. North_Sales is in the primary role. Then set the configuration protection mode to maximum availability. We will create 4 SRLs starting with group# 11. MASTEROBSERVERHOSTS, DGMGRL reports an error if the To optimize the log apply rate: Do not configure the DelayMins database property to delay applying archived redo log files to the standby database (see Managing Log Apply Services for more information). 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. Time for action - using interfaces to monitor Data Guard; Other replication solutions and Data Guard; You can use this information to identify ahead of time any redo transport configurations that would be incorrect after a role change, including any standbys that will not receive redo because the RedoRoutes property was not configured correctly. The broker selects a target standby based on the order they are specified in the property. If an application has called this function and it has received a status of SUCCESS, then the master observer attempts a fast-start failover. the observer on ob2-host to become the master Reinstatement of the failed primary database as a new standby database failed. If fast-start failover is initiated, the master observer verifies the target standby database is ready to fail over to the primary database role. For Oracle Database Release 12.2 and higher, Oracle Enterprise Manager Cloud Control (Cloud Control) supports configuring multiple observers using the Enterprise Manager Command Line Interface (EM CLI). See Oracle Data Guard Concepts and Administration for information about tuning the log apply rate for a physical standby database. Group definition this section is optional. Switchover and Manual Failover for more information about switchovers and manual failovers, respectively. Step 4: Enable Fast-Start Failover Now we are ready to enable FSFO: DGMGRL> enable fast_start failover; Enabled in Zero Data Loss Mode. No two observers on the same Data Guard Broker configuration can have the same name. environment that is guaranteed to either lose no data (when the When a fast-start failover occurs because either a user configurable fast-start failover condition is detected or an application initiates a fast-start failover by calling the DBMS_DG.INITIATE_FS_FAILOVER function, the former primary database is always shut down and never automatically reinstated. The observer does not attempt to reinstate the former primary database. milliseconds. You must set both The configuration status returns the SUCCESS status after the observer reestablishes its connection to the primary database, which then notifies the target standby database. This document describes how to setup clients to connect to Data Guard databases (primary and standby) and configure automatic client failover such that in case there is role change due to switchover or . US Coast Guard Auxiliary. The broker controls the rest of the switchover. You cannot perform a switchover to a snapshot standby database unless you first convert it back to a physical standby database. 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. This file A complete failover is the recommended and default failover option. The FS_FAILOVER_OBSERVER_PRESENT column displays YES for the target standby database. The broker interacts with Oracle Clusterware or Oracle Restart to ensure that the appropriate database services are active and that the appropriate FAN events are published after a role change. After step 1 finishes, Switch the original physical standby db STAN to primary role; Fast-start failover is enabled, but this standby database is not the target of the fast-start failover. The subdirectories that DGMGRL creates under this directory will also have the If fast-start failover is enabled you can still perform a switchover or a manual failover as long as certain conditions are met. For a system to process an instruction involving data access, these are the certain steps involved: Fetch the block of data from the hard disk (secondary/permanent storage) to the primary memory (e.g. gets enabled and then begins monitoring. Reinstating the Former Primary Database in the Broker Configuration for more information about reinstatement. After an immediate failover completes, all the standby databases in the configuration, regardless of their type, are disabled. When this property is set to the default value of 0, it prevents the observer from periodically establishing a new connection with the primary database. 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. Broker can be configured to initiate failover on any of the following conditions. The reinstated database acts as the fast-start failover target for the new primary database, making a subsequent fast-start failover possible. Configure one or more active standby databases Minimize downtime for upgrades Oracle Data Guard configuration with DGMGRL. Step:1 Check the database role and open_mode Starting the Observer as a Background Process Using 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. FastStartFailoverThreshold for reference information about the FastStartFailoverThreshold property. Change Standby to Primary Database. See the Cloud Control online help for more information. DNS CNAME) that always resolves to the primary. If the configured data loss guarantee cannot be upheld, The service can be started on the physical standby only after the redo generated by starting the service has been applied. Oracle also provides Fast Application Notification (FAN) for OCI clients and Fast Connect Failover for JDBC clients. Check the database role,open_mode in standby server. If there is more than one standby database in the configuration, you must explicitly set the FastStartFailoverTarget property on the primary database to name one or more candidate target standby databases. Use the EMCLI verb dg_configure_observers. Ensure SPFILE is used SQL> sho parameter spfile 2. The observer does not need to coordinate fast-start failover when fast-start failover is disabled, so the primary and target standby do not nominate a master observer until fast-start failover is enabled.

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