required permissions, the admin folder is created If the protection mode was at maximum availability or maximum performance, it remains unchanged. configuration file the preferred method for starting an observer. 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. Oracle Database PL/SQL Packages and Types Reference, Stop the observer from any computer system in the broker configuration, as described in, Start the observer on the new computer system, as described in Step 8 of, Enable fast-start failover using the DGMGRL, Shut down the primary database and the target standby database using either DGMGRL, Oracle Database Global Data Services Concepts and Administration Guide, Oracle Real Application Clusters Administration and Deployment Guide, Configure the connect descriptor for connect-time failover. redo generation on the primary database will be stalled. usually within three seconds if fast-start failover is enabled. there is a lost network connection, be aware that the observer may attempt a SHOW OBSERVER command to confirm that the switch took place. These SQL> startup ORACLE instance started. Immediately after issuing command in step 2, shut down and restart the standby instance STAN: ConfigurationSimpleName represents observer and the others are backup observers. In cases where The primary database was shut down without using the ABORT option. fast-start failover through Cloud Control. If these parameters are modified outside of Broker, it raises a warning. Some properties have changed between those releases. Figure 6-2 The Observer in the Fast-Start Failover Environment. Always try to perform a complete failover first unless redo apply has stopped at the failover target due to an ORA-752 or ORA-600 [3020] error. 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. In the media recovery phase, Flashback Database applies redo to bring the database up to the standby_became_primary_scn. directory does not have the required permissions, broker does the following: When you run DGMGRL commands, if a path and file name are explicitly specified for You can find detailed information about all observers, including master observers and backup observers, in the V$FS_FAILOVER_OBSERVERS view. Use broker configuration properties to set the time taken to detect a See START OBSERVER IN BACKGROUND for more information Remember to check Flashback Database history before aborting the primary. This means that in order for a flashback database operation to succeed, observer and the standby both lose contact with the primary. If a group name is not specified, then SHOW OBSERVERS alone is also a valid command. 4. 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. Oracle Data Guard Broker is a utility that can help you manage your Oracle Data Guard. After the restart, Redo Apply begins applying redo data from the new primary This table describes the optional database properties that you can set. Expected output is shown in blue text. This will signal the observer to initiate failover after the FSFO threshold timeout has been reached (default is 30 seconds). This is called failover. To stop the observer, see Stopping the Observer. Issue the following command while connected to any database in the broker configuration, except the database that is to be reinstated: The newly reinstated standby database will begin serving as a standby database to the new primary database. status before the crash. A switchover is a role reversal between the primary database and one of its standby databases. automatic failover feature in configurations set up for zero data loss protection at any Use the VALIDATE STATIC CONNECT IDENTIFIER command to ensure the static services have been configured correctly. The default By choosing the standby database with the least amount of unapplied redo, you can minimize the overall time it takes to complete the switchover operation. If the primary database does not have connectivity with the target standby database, fast-start failover remains enabled on the target standby database and the observer may still attempt a fast-start failover if conditions warrant a failover. 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. The target standby database is enabled and is in the APPLY-ON state. If you intend to switch back to the original primary database relatively soon, you may allow the physical and snapshot standbys to remain disabled. Flashback Database is a continuous data protection (CDP) solution integrated with the Oracle Database. 1. Reset database properties related to Redo Apply services, such as DelayMins. the service configuration. 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. Services that must be active in any given database role (primary, physical standby, logical standby, or snapshot standby) must be configured with the Server Control utility (SRVCTL) explicitly on each database where the service must be active. FastStartFailoverLagLimit Now that we know switchovers work, it's time to test failovers. Note: if the observer loses contact with the primary, but the standby does not, the observer can determine that the primary is still up via the standby. You can enable fast-start failover from any site while connected to any database in the broker configuration. FSFO uses Flashback Database as part of the process of reinstating a failed primary as a standby. post-callout script, and pre-callout success file for the broker disable fast-start failover with the FORCE option on the A failover to a physical standby database is preferable because 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. In this example, there are 3 ORLs with a max group# of 3. You can manually stop a specific observer or all observers. Prerequisites for Enabling Fast-Start Failover provides complete information about all of the fast-start failover and reinstatement requirements. However, you can change the name or the location of the file if you start the observer using the DGMGRL START OBSERVER command and include the FILE IS qualifier. What is true about Data Guard setup with fast-start failover? process. failover with the FORCE option on the primary database. Switchover and Manual Failover for more information about switchovers and manual failovers, respectively. Immediately after issuing command in step 2, shut down and restart the former primary instance PRIM: In previous releases, OCI and ODP.NET clients receive FAN notifications via Oracle Advanced Queuing (AQ). If the value is non-zero, failover is possible any time the standby database's apply The commands that can be executed for a group of configurations (as declared in an observer configuration file) are as follows. Only two databases, the primary and the failover target, can be in the FSFO configuration at any given time. Relationship Between Primary, Target Standby, and Observer During Fast-start Failover. Note that if the V$DATABASE.FS_FAILOVER_STATUS column has a value of DISABLED, then any values returned for the remaining columns related to fast-start failover (V$DATABASE.FS_FAILOVER_*) become irrelevant. on particular instances based on the service configuration. Once Flashback Database has succeeded, the observer will convert the database to a standby, bounce it, and begin apply services. The failover time is dependent upon whether the target standby database (physical or logical standby database) has applied all of the redo data it has received from the primary database. Valid values are >= 100. For Fast Connection Failover (FCF) to occur, a client must be able to locate the new primary database after a failover. The column value for V$DATABASE.FS_FAILOVER_STATUS will be SYNCHRONIZED in a configuration operating in maximum availability mode, and it will be TARGET UNDER LAG LIMIT in a configuration operating in maximum performance mode when ready to fast-start failover. This is because the -role qualifier is taken into account only by Data Guard broker, and at database startup. In maximum availability mode, set the LogXptMode database property for both the primary and target standby databases to SYNC or FASTSYNC. configuration named ConfigurationSimpleName. 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. If fast-start failover is enabled, then a switchover can be performed only to the pre-specified target standby database and only if the standby database is synchronized with the primary database or is within the configured lag limit, for the max availability and max performance modes respectively. To move the observer to another computer: There is no need to disable fast-start failover when you move the observer. To protect the files, it's good practice to store them in separate filesystems. The physical and snapshot standby databases will have to be re-created from a copy of the new primary database. Complete Failovers in Configurations Using Far Sync Instances. See the Oracle Maximum Availability Architecture technical briefs at: When setting the FastStartFailoverLagLimit configuration property, consider these tradeoffs between performance and potential data-loss: A low lag limit will minimize data loss but may impact the performance of the primary database. This file contains connect identifiers to both the primary and the target standby databases. 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. Another standby database that does not have connectivity with the primary database, fast-start failover is disabled for this database. The default group is all the configurations defined in the observer configuration file. CONNECT command. What is true about data guard set up with fast-start failover (FSFO) in Oracle Cloud Infrastructure (OCI)? After a failover, the broker publishes Fast Application Notification (FAN) events. 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. There is no need to multiplex SRLs in order to protect redo as with ORLs (the redo is already protected in the ORLs of the primary). The broker initiates a failover after the number of seconds specified by this The previous examples dealt with setting up only one service on a database. You can register up to four observers to monitor a single Data Guard broker configuration. Es gratis registrarse y presentar tus propuestas laborales. If that metadata is pushed out, Oracle can no longer find a fuzzy snapshot so it will not be able to flash back. Figure 6-2 shows the observer monitoring a fast-start failover configuration. A switchover is a role reversal between the primary database and one of its standby databases. The former primary database is disabled. To help you select an appropriate switchover or failover target, use the following DGMGRL commands which perform checks on the database to determine its readiness to complete a role change. FSFO can provide substantial gains in high availability and disaster recovery preparedness for all environments, from inexpensive Cloud-based systems to global distributed data centers. may allow the primary database to continue redo generation after This can be avoided by first disabling fast-start failover with the FORCE option on the target standby. 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. File. Now it will return PRIMARY. There are normally two situations when this operation will be performed: a planned outage for maintenance of the primary database or disaster recovery. We'll start with switchovers. The only exception to this is failovers to snapshot standby databases. When fast-start failover is enabled, the broker determines if a failover is necessary and initiates the failover to the current target standby database automatically, with no need for manual intervention. 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. The word ALL cannot be used as a group name because it is a reserved keyword. When the primary database and the target standby database regain network connectivity, the broker will disable fast-start failover for the entire broker configuration. Therefore, the detection time can be reduced to nearly The connect descriptor can be configured in one of two ways: Oracle Database PL/SQL Language Reference for more information about the DB_ROLE_CHANGE system event. Observers continuously monitor the fast-start failover environment to ensure the primary database is available (described in When Fast-Start Failover Is Enabled and the Observer Is Running). To get started, all you'll need is Oracle Database Enterprise Edition Release 10.2 or later, a database, and three hosts: two for the databases and a small host for the FSFO observer. Use the SQL ALTER DATABASE MOVE DATAFILE command to rename or relocate an online data file on a physical standby that is a fast-start failover target if the standby is mounted, but not open. the observer was killed after the stall began, but before the failover timeout had elapsed). LGWR is unable to write to any member of the log group because on an I/O error. Its primary job is to perform a failover when conditions permit it to do so without violating the data durability constraints set by the DBA. The broker may not be able to disable fast-start failover on all databases in the broker configuration when you issue the DISABLE FAST_START FAILOVER FORCE command. The observer is the third party in an otherwise typical primary/standby Data Guard configuration. The original primary database can now be configured as a standby. You can issue a To stop it, you can do either of the following: Choose the Stop Observer option on the first page of the fast-start failover wizard and click Continue at the bottom of the page. This support note is available at http://support.oracle.com. A fast-start failover to the target standby database fails. The default value is ALL. commands. The broker reinstates the database as a standby database of the same type as the former standby database of the new primary database. Event notification and database connection failover support is available to database clients connected to local database services when a broker-managed failover occurs. environment variable must have exclusive permissions wherein it can be accessed only alter database recover managed standby database finish; alter database activate standby database; Managed recovery process has been stopped between primary and standby database and standby becomes primary database. You must use the Oracle wallet to store the credentials for all broker configurations to be managed. fast-start failover succeeds, if a post-callout script is specified in the fast-start Setting it to 'FALSE' leaves the database open and stalled until it is terminated or signaled to proceed in the event a failover did not take place (e.g. Once an observer is started, no further user interaction is required. observer immediately begins monitoring the status and connections to SQL>connect /@STAN as sysdba Upon detecting the break in communication, the observer attempts to reestablish a connection with the primary database for the amount of time defined by the FastStartFailoverThreshold property before initiating a fast-start failover. The target standby database when it does not have connectivity with the primary database, fast-start failover is disabled only on the target standby database. Broker Configuration Has Only One Registered Observer. If only a path is specified, the files are ObserverConfigFile is a DGMGRL session runtime property. To use a far sync instance with fast-start failover, the far sync instance transport mode must be set to either SYNC or FASTSYNC and the target standby database transport mode must be set to ASYNC. The VALIDATE FAST_START FAILOVER command parses the callout 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. Among many benefits of using this utility, I highlight that while using it, it will not need manual intervention to recover the databases or eventually a switchover in case the primary database becomes unavailable. When running the START data (in seconds) specified by the In the following example commands, a service named PAYROLL is configured to be active in the PRIMARY role on the primary database NORTH. It also requires Flashback Database to be enabled on both the primary and target standby databases. For Oracle RAC databases, see Oracle Real Application Clusters Administration and Deployment Guide for more information about configuring database services with the SRVCTL utility. fsfo_hostname.dat. configuration property specifies how frequently the observer Disabling Fast-Start Failover Using DGMGRL. Restart the database to the mounted state, Use Cloud Control or DGMGRL to reinstate the database. Make sure that xdpyinfo exist under PATH variable. Switchover Steps. Disable fast-start failover using the DGMGRL DISABLE FAST_START FAILOVER command. committing because a fast-start failover may have occurred while it was To install Oracle Data Guard, you need to create two Azure VMs on the same availability set: The primary VM (myVM1) has a running Oracle instance. 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. This is the recommended method for disabling fast-start failover. However, if you want the observer to reconnect to the primary database periodically as a means of testing the health of the network connection to the primary, then use the ObserverReconnect configuration 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). If the target is a snapshot standby database, the broker first converts the database to a physical standby database. You can upgrade the protection mode later, if necessary, as described in Setting the Protection Mode for Your Configuration. 3. Alternatively, use the RedoRoutes property to configure the redo transport mode for the target standby and the database currently in the primary role. The foundation of FSFO is Data Guard - a primary and at least one standby. this directory are used to store the files related to the Have a means of notifying someone if standby apply falls too far behind. 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). You might, for instance, use this to allow the observer to monitor the databases using the same connect identifiers as the client applications. 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. Depending on the failover and the types of standby databases involved, some of the databases may need to be reinstated or re-created. Table 6-2 FS_FAILOVER_STATUS Column of the V$DATABASE View. 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. 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. 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. 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. Standby databases that are disabled during switchover, manual failover, or fast-start failover will not be automatically reinstated. The existence of a .suc file, Change Standby to Primary Database. fsfo_postcallout are stored in the same location as These conditions are described in the following table: Dictionary corruption of a critical database. directory does not have the required permissions. FastStartFailoverThreshold for reference information about the FastStartFailoverThreshold property. Most of the network services used in a FSFO environment may use dynamic registration, but to enable Broker to restart instances during role transitions or during reinstatement after a failover, you must define a static service named db_unique_name_dgmgrl.
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