There's a big difference between a system that's FSFO enabled and one that's FSFO ready. (Yes, bystanders need Flashback Database too). Written by authors well-known for their talent with RAC, Pro Oracle Database 11g RAC on Linux . The name of the callout configuration scripts is specified in Reinstating the Former Primary Database in the Broker Configuration for more information about reinstatement. 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. To stop the observer when fast-start failover is disabled, the primary database must be running. You have done a failover to your Standby database so it becomes the new Primary. All database connections associated with the observer, including the initial connection, must use dedicated server connections. Displays only on a logical standby database that has not yet completed loading a copy of the primary database's data dictionary. To enable fast-start failover, both the primary and target standby databases must be running and have connectivity, and satisfy all of the prerequisite conditions listed in Prerequisites for Enabling Fast-Start Failover. Enabling fast-start failover does not trigger a failover. A switchover guarantees no data loss and is typically done for planned maintenance of the primary system. If you initiated a complete failover and it fails, you might need to use immediate failover. You can customize fast-start failover setup for a specific application by using the DBMS_DG PL/SQL package. upheld. The existence of a .suc file, North_Sales is in the primary role. 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. 4. On the Oracle Data Guard Overview page, click Database must be reinstated. (Oracle Call Interface) client that connects to the primary and target standby databases The physical and snapshot standby databases will have to be re-created from a copy of the new primary database. drain_timeout amongst the active services. Start the observer by running dgmgrl and logging in using SYS credentials. configuration property. Other members of the configuration will receive redo from the designated redo source based on the new primary. *PATCH v5 0/6] Add Toshiba Visconti Video Input Interface driver @ 2023-01-11 2:24 Yuji Ishikawa 2023-01-11 2:24 ` [PATCH v5 1/6] dt-bindings: media: platform: visconti: Add Toshiba Visconti Video Input Interface bindings Yuji Ishikawa ` (5 more replies) 0 siblings, 6 replies; 42+ messages in thread From: Yuji Ishikawa @ 2023-01-11 . The primary database can be reinstated if it had flashback database enabled. Do not attempt to reinstate the old primary database if an ORA-752 or ORA-600 [3020] error has occurred at the failover target. The broker preserves the protection mode that was in effect prior to the failover. observer, whether it is currently connected to the primary and target standby databases, When you configure data guard using OCI console, the default mode is set to maxprotection. Determines whether or not any standby databases that did not participate in the failover operation have applied redo data beyond the new primary database, and thus need to be disabled. 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). $DG_ADMIN/config_ConfigurationSimpleName/callout 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. The new primary database is opened in read/write mode and redo transport services are started. However, there may be exceptions to the recommendation to choose a physical standby database as the target standby database. Oracle 12c-Step by Step Manual Data Guard Failover. Installing and starting an observer is an integral part of using fast-start failover and is described in detail in the following sections: Oracle Data Guard Installation explains that you can either install only the Oracle Client Administrator or you can install the complete Oracle Database Enterprise Edition or Personal Edition on the observer system. command for more information about starting the ASYNC. It may be possible to convert the old Primary into a Standby database now instead of having to do a time consuming duplicate again. A switchover guarantees no data loss. Cancel MRP process. This document only talks about switchover involving physical standby database. 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). Startup can fail with "ORA-16647: could not start more than one observer" even when no observer is actually running if the previous observer process terminated without deregistering itself and the new observer isn't using the previous fsfo.dat file. The role change is directed to the same standby database that was specified for the FastStartFailoverTarget database property on the primary database. Configure the TNSNAMES.ORA file on the observer system so that the observer is able to connect to the primary database and to the pre-selected target standby database. The broker allows a complete failover to proceed as long as there are no errors present on the standby database that you selected to participate in the failover. Step-by-step instructions for manual reinstatement are described in Reenabling Disabled Databases After a Role Change. For Oracle RAC databases, see Oracle Real Application Clusters Administration and Deployment Guide for more information about configuring database services with the SRVCTL utility. SHOW OBSERVER command to confirm that the switch took place. FastStartFailoverLagLimit property. Provides an automatic failover environment that The ObserverOverride and ObserverReconnect properties allow you additional control over the connection to the primary. This example shows the verbose mode of the 'show configuration' command that provides FSFO-specific information. Observer sites monitor the fast-start failover environment. POTENTIAL DATA LOSS: Fast-start failover is enabled with some data loss. Broker can be configured to initiate failover on any of the following conditions. Commit latency is not affected by redo transfer, but committed transactions whose redo has not been received by the standby will be lost during failover. Verify Before Switch-over: Log in as a test user and make some changes that won't impact other parts of the system. The NetTimeout property specifies the number of seconds LGWR will block waiting for acknowledgment from the standby in synchronous mode before considering the connection lost (corresponds to the NET_TIMEOUT option of log_archive_dest_n). What is true about Data Guard setup with fast-start failover? Configure the protection mode. The database on which the procedure is called notifies the observer. file, observer runtime data file (fsfo.dat), fast-start failover callout FastStartFailoverLagLimit property. 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. The remaining Data Guard-related parameters will be set by Broker later in the walkthrough. Broker stores it configuration information in a mirrored set of files outside the database. 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. The broker first converts the original primary database to run in the standby role. The observer does not attempt to reinstate the former primary database. The only exception to this is failovers to snapshot standby databases. 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. STANDBY>connect /@STAN as sysdba After the broker receives the STOP OBSERVER request, the request is passed to the observer the next time the observer contacts the broker, and the observer then stops itself. Use broker configuration properties to set the time taken to detect a You can also query the V$FS_FAILOVER_STATS view to display statistics about fast-start failover occurring on the system. STOP OBSERVING, and SET files to automate tasks that must be performed before and after a fast-start failover To prevent automatic reinstatement of the former primary database in these cases, set this configuration property to FALSE. Using Cloud Control, you can view the value of the ApplyLag column for each standby database in the Standby Databases section of the Oracle Data Guard Overview page. Flashing back a database occurs in two stages: For FSFO environments, set db_flashback_retention_target = 60 or higher to provide sufficient Flashback Database history for automatic standby reinstatement. If a bystander standby database is not disabled by the broker during this failover, it will remain in the state it was in before the failover. 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. What is true about data guard set up with fast-start failover (FSFO) in Oracle Cloud Infrastructure (OCI)? Another consequence of immediate failover is that all other databases in the configuration are disabled and must be reinstated or re-created before they can serve as standby databases for the new primary database. The observer host is 'observer.demo.org'. The broker allows an immediate failover to proceed even if there are errors present on the standby database that you selected to participate in the failover. primary database must have network connectivity. A normal shutdown prevents a fast-start failover until the primary database and standby database are connected and communicating again. There can be up to four observers for a single Data Guard configuration. You Example 6-2 Sample Observer Configuration File. FSFO is a feature of Broker which records information about the failover target, how long to wait after a failure before triggering a failover, and other FSFO specific properties. Currently, this state can be detected only when the database is open. If the protection mode was at maximum protection, it is reset to maximum performance. broker opens all the PDBs on the new primary database and on the target standby A switchover is a role reversal between the primary database and one of its standby databases. Create a trigger based on the, Oracle Database PL/SQL Language Reference, Choosing a Target Standby Database for Switchover, Choosing a Target Standby Database for Failover, Scenario 9: Performing a Switchover Operation, Scenario 10: Performing a Manual Failover Operation, Database Service Configuration Requirements, Troubleshooting Problems During a Switchover Operation, How the Broker Performs a Complete Failover Operation, How the Broker Performs an Immediate Failover Operation, Setting the Protection Mode for Your Configuration, Scenario 7: Enabling Fast-Start Failover When a Far Sync Instance Is In Use, Description of "Figure 6-1 Relationship of Primary and Standby Databases and the Observer", Enabling Fast-Start Failover Task 7: Configure Actions Before and After Fast-start Failover (Optional), Directing a Fast-Start Failover From an Application, Fast-start Failover Callout Configuration Files, Oracle Data Guard Command-Line Interface Reference, Description of "Figure 6-2 The Observer in the Fast-Start Failover Environment", Oracle Enterprise Manager Command Line Interface. Switchover and Manual Failover for more information about switchovers and manual failovers, respectively. 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. Fast-start failover enables the Data Guard broker to rapidly and automatically failover to a previously chosen standby database without requiring manual intervention. WAIT option, broker waits for the amount of disable fast-start failover with the FORCE option on the ConfigurationSimpleName is created. You want to prevent fast-start failover from occurring because the primary database will resume service soon. The syntax for the configuration declaration is: The definition for each broker configuration is: The configuration-name can be different from the name defined in the metadata of the Data Guard Broker configuration. Follow the guidelines described in Choosing a Target Standby Database. 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. The former primary database is disabled. 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. Data Guard broker does not manage or store credentials. 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. When the configuration has only one registered observer, if the primary and target standby databases stay connected but the connection to the observer is lost, then the broker reports that the configuration is not observed. In this case fast-start failover cannot occur because the databases are not ready to failover. specified, the file is stored in an appropriate directory under the broker's The log file name is specified with the LOGFILE IS option of the START OBSERVER command. DGMGRL to manage multiple observers on multiple configurations. When the standby becomes available again, the primary and standby re-synchronize and resume synchronous redo transfer. To enable fast-start failover in Cloud Control, use the Fast-Start Failover wizard. If an application has called this function and it has received a status of SUCCESS, then the master observer attempts a fast-start failover. 3. Database dismounted. However, you do have the option of specifying a name and location for the observer configuration file. See Directing a Fast-Start Failover From an Application). To allow the master observer to automatically reinstate the former primary database, the database must be started and mounted. When you select a standby database to be the next primary database after a switchover or a failover, there are several factors to consider. For systems with multiple RAID controllers, consider creating SRLs such that their IO is balanced across the controllers. from another DGMGRL session. 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. The redo transport mode used to send redo to the target standby database or the database currently in the primary role. This allows Data Guard to remain functional during maintenance periods when the application listeners are down. the primary and target standby databases. 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. 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. If this issue commands and interact with the broker configuration. You can specify particular conditions for which a fast-start failover should occur using either Cloud Control or the DGMGRL ENABLE FAST_START FAILOVER CONDITION and DISABLE FAST_START FAILOVER CONDITION commands. On Windows, the directory specified by the DG_ADMIN But it will also continue trying to reconnect to the primary database indefinitely. Multiplexing SRLs merely adds unnecessary IO and can increase commit latency. It's secondary job is to automatically reinstate a failed primary as a standby if that feature is enabled (the default). In 10g, a single wallet can be used for multiple observers, but they must all use the same SYS password. If you cannot tolerate any loss of data, then ensure that the configuration protection mode is set to maximum availability or maximum protection. 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. For information about enabling fast-start failover, see Enabling Fast-Start Failover. configuration property. When this property is set to NONE, the broker will disable all bystander standby databases without checking whether they have applied more redo data than the new primary database. An immediate failover should only be performed when a complete failover is unsuccessful or in the error cases just noted. alter database recover managed standby database cancel; Step:3 The below commands will help to bring up standby as primary. occurred to the target standby database prior to disabling fast-start configuration. Whether or not you need the FORCE option depends mostly on if the primary and target standby database have network connectivity: If the primary and target standby database have network connectivity, and the database to which you are connected has network connectivity with the primary database, the FORCE option has no effect. environment variable is set and the specified directory has the Required fields are marked *. You can optionally indicate the database health conditions that should cause fast-start failover to occur. If the database is not managed by Oracle Clusterware, If the group name is not provided, then a new observer is started for each broker configuration defined in observer.ora. If failover occurs to a logical standby database, all physical and snapshot standby databases will be disabled by the broker. The required attributes vary depending on your configuration (including whether your environment is Oracle RAC-based or single-instance). Fast-start failover quickly and reliably fails over the target standby database to the primary database role, without requiring you to perform any manual steps to invoke the failover. A manual failover is already in progress. Enabling Fast-Start Failover describes how to start observers as a part of the step-by-step process to enable fast-start failover. DGMGRL> show configuration Configuration - CDB01_fraad1_CDB01_fraad3 Protection Mode: MaxAvailability Members: CDB01_fraad1 - Primary database CDB01_fraad3 - (*) Physical standby database Ensure SPFILE is used SQL> sho parameter spfile 2. time specified in the WAIT option. Remote login is required, along with a password file, to allow the databases in a Data Guard configuration to connect to each other. However, re-enabling Flashback Database will require a bounce since the database must be mounted and not open. See Choosing a Target Standby Database for helpful advice. This may result in two databases in the configuration simultaneously assuming the primary database role. If groups are not defined, you can still operate on all configurations defined in the file as a whole. The act of switching roles should be a well-planned activity. DGConnectIdentifier, "Scenario 9: Performing a Switchover Operation" for an example of using the VALIDATE DATABASE command to show a database's readiness to complete a role switchover, "Scenario 10: Performing a Manual Failover Operation" for an example of using the VALIDATE DATABASE command to show a database's readiness to complete a role failover. required permissions, the admin folder is created 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. the preferred method for starting an observer. See Oracle Enterprise Manager Command Line Interface. See the START OBSERVER command for more information. Controlfile is permanently damaged because of a disk failure. Do this prior to every failover test. 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 directory has the same permissions as its parent directory.
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