In this mode, no actual changes are made to your Broker configuration. occurred to the target standby database prior to disabling fast-start The ObserverReconnect configuration property specifies how often the observer establishes a new connection to the primary database. During a complete failover, the broker performs the failover steps described in How the Broker Performs a Complete Failover Operation. LGWR is unable to write to any member of the log group because on an I/O error. callout configuration file. This document only talks about switchover involving physical standby database. 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. ConfigurationSimpleName represents session. the current working directory. This allows for redundancy in your Data Guard observer setup as well. In case of primary database failure, you will need to perform failover to transition the standby database to the primary role. The same process should work for RAC environment as my colleague has . 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. file (fsfo.dat). Reinstate the original primary database to act as a standby database in the new configuration. maximum availability and maximum performance modes, to avoid a return until you issue the STOP OBSERVER command Reinstatement will have to be accomplished by other means (manual or scripted Broker commands). 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. To do this, use the SET ObserverConfigFile and SHOW ObserverConfigFile commands. groups used by multiple configuration commands. WAIT option, broker waits for the amount of In a complete failover, it is also possible to failover to a standby database (terminal standby) that gets redo from another standby database (cascader). Another good test is to simulate network failures that leave the primary up, but isolated from the failover target standby and the observer. The FS_FAILOVER_STATUS column in the V$DATABASE view for the target standby database displays a reason why fast-start failover cannot occur. Multiplexing SRLs merely adds unnecessary IO and can increase commit latency. Only two databases, the primary and the failover target, can be in the FSFO configuration at any given time. Currently, this state can be detected only when the database is open. The broker continuously monitors for all sessions that are connected Unlike ORLs, SRLs should be created with only one member per group. This may result in data loss. To maintain a viable disaster-recovery solution in the event of another disaster, you may need to perform additional steps. A value of TRUE helps to ensure that an isolated primary database cannot satisfy user queries. In fact, failovers are so reliable, fast, and simple that switchovers become the exception rather than the rule. physical standby database. 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. 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. 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 . In addition, the primary database will shut down if it perceives a loss of connectivity for a period longer than FastStartFailoverThreshold seconds, if the FastStartFailoverPmyShutdown configuration property is set to TRUE. The FS_FAILOVER_OBSERVER_PRESENT column, which indicates whether the observer is running and actively pinging the database. observer computer is returned to you so that you can continue to There are many examples, and Ritesh Chhajer offers this example of doing a Data Guard switchover using dgmgrl: 1. A normal shutdown uses SHUTDOWN NORMAL, SHUTDOWN IMMEDIATE, or SHUTDOWN TRANSACTIONAL. 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. Bystander standby databases can be shut down at any time in any order without impacting fast-start failover. Regardless of the method you choose, the broker coordinates the role transition on all databases in the configuration. If you cannot tolerate any loss of data, then ensure that the configuration protection mode is set to maximum availability or maximum protection. Automatic failover quickly and reliably fails over the standby Autonomous database to the primary database role, without requiring you to perform any manual steps. Commands For Managing Observers on Multiple Configurations. This action will result in loss of data and the possibility of two databases in the configuration simultaneously assuming the primary database role. Note that if failover was performed on a snapshot standby database, the old primary must be either reinstated or re-created as a physical standby database. This support note is available at http://support.oracle.com. After the patch has been successfully applied to all databases, take the following steps to enable fast-start failover and start the observer. This is particularly useful when registering with multiple listeners where the parameter value would otherwise exceed the 255 character limit. Create a unique connect alias for each database. In this mode, the FastStartFailoverLagLimit configuration property is set to zero. See Manual Failover for information about manual failover. configuration scripts and checks for errors or misconfigurations. If the observer is stopped abnormally (for example, by typing CTRL/C), restart it and reference the existing fsfo.dat file with the FILE IS qualifier. During the failover to the physical standby database, the Oracle 11g DGB performs the following steps: First, it validates that the target standby database is ready to accept the primary role. The value specified for either of these properties should allow the master observer to connect to any instance of an Oracle RAC database. See Reenabling Disabled Databases After a Role Change. $DG_ADMIN/config_ConfigurationSimpleName/callout The rest of this section provides examples of using DGMGRL SHOW commands to display fast-start failover information and includes sections describing the following views: The DGMGRL SHOW FAST-START FAILOVER command displays all the fast-start failover related information. Step-by-step instructions for manual reinstatement are described in Reenabling Disabled Databases After a Role Change. STANDBY>ALTER DATABASE OPEN; However, there may be situations in which you must disable fast-start failover when ERROR: Unable to verify the graphical display setup. Refer to the appropriate Oracle RAC or Oracle Restart documentation for further information. These tasks assume that you are connected as SYS or SYSDG and that a primary and standby database are already set up in a broker configuration. you need to make the primary database available, first confirm that a not already enabled, the observer waits until fast-start failover The terminal session will appear to hang at this point. Oracle Database 11g FSFO adds support for Maximum Performance mode (async redo transfer), providing the flexibility to trade durability for performance. the observer was killed after the stall began, but before the failover timeout had elapsed). If you are more concerned about the performance of the primary database than a minimal loss of data, consider enabling fast-start failover when the configuration protection mode is set to maximum performance. services. In order for Flashback Database to succeed, there must be sufficient history available in the Flashback Database logs and all of the redo generated between the restore point and the standby_became_primary_scn must be available. 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. Immediate: No additional data is applied on the standby database, resulting in a data-loss . If you are performing an immediate failover, then the database role is changed to primary without applying any accumulated redo data. the observer on ob2-host to become the master Alternatively, you can query the V$DATABASE view on the target standby database. 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. If a failure occurs once a reinstatement operation (automatic or manual) is underway, the broker logs the appropriate information in the broker configuration files and broker log files. 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. Write Engineering Change Proposal documentation and reports to request permission to install, replace . Make sure that xdpyinfo exist under PATH variable. Slightly less critical than making sure you've got a good primary is making sure the failed primary can be automatically reinstated. A normal shutdown prevents a fast-start failover until the primary database and standby database are connected and communicating again. You can create two callout configuration scripts, a Then the STOP OBSERVER command can be issued successfully on the former master observer. In addition, some standby databases may be disabled by the broker during the failover if the broker detects that they have applied redo beyond where the new primary database had applied. Displays if the standby database's redo applied point lags the primary database's redo generation point by more than the number of seconds specified by the FastStartFailoverLagLimit configuration property and the configuration is operating in maximum performance mode. The guide makes few assumptions about your existing environment and includes examples for creating a physical standby database and Data Guard Broker configuration. 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. In a manual failover, you convert a standby database to a primary database because the original primary database failed and there is no possibility of recovering the primary database in a timely manner. Verify the target standby database is ready for failover. Fast-start failover allows the broker to automatically fail over to a previously chosen standby database in the event of loss of the primary database. The Appendix provides information oncreating a simple wrapper script to start the observer as a background process. The following paragraphs describe the supported availability modes. They must be re-created before they can serve as standby to the new primary database. You must set both Do not use Shared Server (formerly MTS) for Data Guard. Now we will see a step-by-step approach to perform a switchover between the primary and the logical standby database: . 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. To start the observer with DGMGRL, issue the following Provides an automatic failover 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. this script is run before the fast-start failover is initiated. In this case fast-start failover cannot occur because the databases are not ready to failover. The price for this guarantee is increased commit latency ( log file sync waits). The SHOW CONFIGURATION command will show you which databases can be reinstated and which databases must be re-created. On primary database NORTH, execute the following: On standby database SOUTH, execute the following: Services that are to be active while the database is in the physical standby role must also be created and started on the current primary database regardless of whether the service will be started on that database or not. We suggest you try the following to help find what youre looking for: This document will guide you through configuringOracle Data GuardFast-Start Failover (FSFO) using a physical standby database. Starting the Observer as a Background Process Using 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. 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. While not strictly required, creating a wallet provides a secure way to store the credentials needed to automatically connect to the primary when starting the observer. OBSERVE-ONLY: Fast-start failover is enabled in observe-only mode. However, there may be exceptions to the recommendation to choose a physical standby database as the target standby database. db1_a: Alias to connect to the dynamic Data Guard service on database "a", db1_b: Alias to connect to the dynamic Data Guard service on database "b", db1_a_static: Alias to connect to the static Data Guard service on database "a", db1_b_static: Alias to connect to the static Data Guard service on database "b". If the target standby database is a snapshot standby database, all of its instances must be restarted to the mount mode before performing failover. 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 master observer never waits for the threshold to expire to perform a fast-start failover in the following situations: If the master observer determines that any of the user-configurable conditions has been detected, then it attempts a fast-start failover. 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. You must use the Oracle wallet to store the credentials for all broker configurations to be managed. You can disable fast-start failover if necessary, by using the FORCE option. If the observer finds that the database is no longer the primary, it will attempt to reinstate it as the failover target standby. Initiate the failover on the standby database STAN: If the configured data loss guarantee cannot be upheld, Don't initiate failover unless at least 30 minutes of history is available. An existing connection which is already closed from the database side would throw an error. Oracle Database Reference for more information about the V$FS_FAILOVER_OBSERVERS view. These facilities allow applications written to take advantage of them to receive asynchronous notification of database events, including role transitions. have received all the redo data the primary has generated in order for automatic failover to The following example displays the contents of the fast-start failover If the primary database has multiple standby databases, then you can specify multiple fast-start failover targets, using the FastStartFailoverTarget property. usually within three seconds if fast-start failover is enabled. once the target standby database's redo applied point is no longer lagging behind the primary To achieve FastStart Failover Ensues: Disaster strikes the primary database and its network connections to both the observer and the target standby database are lost. The observer is the key element that separates Data Guard failover from its pre-FSFO role as the plan of last resort to its leading role in a robust high availability solution. If you are performing a complete failover, then all accumulated redo data is applied before the database role is changed to primary. callout directory. 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. FB Page:https://www.facebook.com/dbahariprasath/? You can start, stop, and show observers for a group of configurations. This is a good time to enable FSFO to make sure that all of the prerequisites have been met. configuration named ConfigurationSimpleName. fast-start failover. change tracking enabled, broker enables block change tracking on the new 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. 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. Alternatively, if you intend to switch back to the original primary relatively soon, then you may re-enable the disabled standby databases after the switch back. If you have an Oracle RAC primary database, consider specifying a higher value to minimize the possibility of a false failover in the event of an instance failure. Client-side broker Es gratis registrarse y presentar tus propuestas laborales. Use the Cloud Control Fast-Start Failover wizard or the DGMGRL ENABLE FAST_START FAILOVER command to enable fast-start failover. It's good practice to use separate listeners for application connections and Data Guard connections. To stop the observer, see Stopping the Observer. 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. For switchovers, understanding all of the factors can simplify the choice of which standby database to consider as your new primary database. Now test FSFO failover back to the original primary. Reinstate or re-create standby databases in the configuration that were disabled by the broker. At this point, you can either: Disable fast-start failover (described in Disabling Fast-Start Failover) and attempt to open the former primary database, Manually reinstate the former primary database, as described in Reenabling Disabled Databases After a Role Change. Reenabling Disabled Databases After a Role Change describes how to do this. present, you must start the observer manually using the following Data Guard broker does not manage or store credentials. The list is empty by default. For example: You can find information about the master observer by querying the V$DATABASE view. Reinstatement restores high availability to the broker configuration so that, in the event of a failure of the new primary database, another fast-start failover can occur. For information about enabling fast-start failover, see Enabling Fast-Start Failover. Since a fast-start failover (automatic failover) could become a false failover when the observer or the standby database cannot connect to the primary database within a specific time, which may cost the database to lose some transactions followed by reinstating or recreating the standby database (the former primary database).