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. For more information, see START OBSERVER IN BACKGROUND. If there is another standby database that is available for failover, you can perform a manual failover to that standby database after you first disable fast-start failover using the FORCE option on that standby database. 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. status before the crash. If no value is specified for the The required attributes vary depending on your configuration (including whether your environment is Oracle RAC-based or single-instance). Presetting database properties related to redo transport services, such as LogXptMode, NetTimeout, StandbyArchiveLocation, StandbyAlternateLocation, and RedoRoutes. This is the recommended method for disabling fast-start failover. Oracle Data Guard configuration with DGMGRL. With a value of TRUE for this property, the primary will shut down after being stalled for the number of seconds specified by the FastStartFailoverThreshold property. directory specified by this variable does not exist, or the directory does not have the 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. To start an observer as a background process, use the DGMGRL created under this directory by DGMGRL will also have the same permissions. All standbys other than the failover target are considered bystanders (v$database.fs_failover_status = 'BYSTANDER'). Displays when the primary and target standby databases are synchronized and the configuration is operating in maximum availability mode. Your email address will not be published. Writing the wrapper itself and the means to determine when to execute it are up to you. An observer is a separate OCI client-side component that run on a different computer from the primary and standby databases and monitors the availability of the primary database. Staff support, hardware and software, security (both software and site), network connections, and bandwidth should be equivalent at both sites. Using the db_unique_name of each database as the Oracle Net alias is simple and intuitive. The following paragraphs describe the supported availability modes. db_domain . All other registered observers are considered to be backup observers. For example, perform full level 0 backups weekly and incremental level 1 backups daily. If the target standby database is ready for failover, then the master observer immediately directs the target standby database to fail over to the primary database role. If you re-create the old primary database, it must be created as the standby type of the old standby database. That is, if the observer is connected to any instance in the Oracle RAC, all instances will show a value of YES. Depending on the failover and the types of standby databases involved, some of the databases may need to be reinstated or re-created. Prepare the primary database in advance for its possible future role as a standby database in the context of the overall protection mode (see Managing Data Protection Modes). Alternatively, you can query the V$DATABASE view on the target standby database. If the database is not enabled, you will not be able to perform a failover to this database. Starting with Oracle Database Release 21c, use the DG_ADMIN In maximum availability mode, set the LogXptMode database property for both the primary and target standby databases to SYNC or FASTSYNC. You can customize fast-start failover setup for a specific application by using the DBMS_DG PL/SQL package. first recording that a fast-start failover cannot happen. 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. See FastStartFailoverTarget for more information about this property. What is true about Data Guard setup with fast-start failover? FastStartFailoverLagLimit To start the observer with DGMGRL, issue the following Verify the standby database instance is mounted. For example: Fast-start failover occurs if both the observer and the target standby database lose connection to the primary database for the period of time specified by the FastStartFailoverThreshold configuration property. 3. If failover is not possible for some reason, then the master observer will continue checking whether the standby database is ready to fail over. 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. Stores the observer runtime data file and observer configuration file in Apply services on all other bystander standby databases automatically begin applying redo data received from the new primary database. DG_ADMIN environment variable is not set, the files are stored in required permissions, DGMGRL reports an error. Switchover to a logical standby database is disallowed when the configuration is operating in maximum protection mode. Please contact us at contactus@smarttechways.com. You cannot create the standby DB system in a different AD from the primary DB system. It is then started and stopped on the primary database. SQL>STARTUP; For information about event notification and database connection failover support for global services, see the Oracle Database Global Data Services Concepts and Administration Guide. must ping the primary database. 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. Queries and DML will continue to run - only sessions that commit will block. Verifies that the target standby database is enabled. Transitions the target standby database into the primary role, opens the new primary database in read/write mode, and starts redo transport services. Now it will return PRIMARY. alter system set standby_file_management=auto; This parameter must be set before the primary can be opened in Maximum Availability mode. 2. Archiver is unable to archive a redo log because the device is full or unavailable. 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. Now test FSFO failover back to the original primary. After the restart, Redo Apply begins applying redo data from the new primary With FSFO enabled, Broker expects to find an observer, which we haven't started yet, so if you verify the at this point with 'show configuration', Broker will report a warning (if it doesn't, give it a minute to discover that the observer isn't there). To see Manual Switch Over Manual SwitchOver in Oracle To see Manual Fail Over Manual Failover in Data Guard With Oracle Data Guard [] See the START OBSERVER command for more information. Failing over the database won't do much good if applications and other database clients don't know where the primary went. Immediately after issuing command in step 2, shut down and restart the standby instance STAN: Specifying Preferred Observers Based on Current Primary. Note that the new primary database does not need to be restarted. Determining a Database's Readiness to Change Roles. Switching over to a logical standby database results in the snapshot and physical standby databases in the broker configuration being disabled by the broker, making these databases no longer viable as standby databases. broker configuration, you must connect through another DGMGRL client You will then need to re-create the physical standby databases from a copy of the new primary database before you can reenable them. In case of primary database failure, you will need to perform failover to transition the standby database to the primary role. Note that role changes to logical standby databases always result in physical standby database bystanders being disabled. If the agent is not file (fsfo.dat). If the configured data loss guarantee cannot be upheld, multi-tenant environments Know the database downgrade steps in case the upgraded database isn't compatible with the environment Discover the features and benefits to the organization when it moves from the old database . 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. If an application has called this function and it has received a status of SUCCESS, then the master observer attempts a fast-start failover. ObserverConfigFile is a DGMGRL session runtime property. 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. You can register up to four observers to monitor a single Data Guard broker configuration. If the WAIT option is included in the Create a wallet and set the default username and password to the database's SYSDBA credentials (usually SYS). Any standby database that was disabled by the broker must be reinstated or re-created, as described in Reenabling Disabled Databases After a Role Change, before it can be a standby database for the new primary database. Write Engineering Change Proposal documentation and reports to request permission to install, replace . 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. Post failover, there are two methods of rebuilding your failed primary Method 1: Rebuild from scratch -> RMAN duplicate Method 2: Flashback database -> only if Flashback was enabled Reinstate failed primary: When you use data guard broker, with just one command, the primary can be rebuilt. This action will result in loss of data and the possibility of two databases in the configuration simultaneously assuming the primary database role. Broker will set the primary to use asynchronous log transport by default. If you have not used the SET ObserverConfigFile command after starting the current DGMGRL client, then the result will always be: ObserverConfigFile=observer.ora. The values that indicate FSFO is ready for failover are listed below. An spfile is required to persist these changes. If the observer finds that the database is no longer the primary, it will attempt to reinstate it as the failover target standby. Otherwise, the DUPLICATE TARGET DATABASE command will fail with "RMAN-20208: UNTIL CHANGE is before RESETLOGS change". (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. failover with the FORCE option on the primary database. observers are registered, a directory named The observer maintains state information in a file. For zero data loss in maximum availability mode, the FastStartFailoverLagLimit property must be set to zero. The primary database can be opened even if there is no acknowledgement from the observer or target standby. database is in the primary role. This If the new primary database was a primary database in the past, and had block Examples of starting observers using DGMGRL are included in Scenario 6: Enabling Fast-Start Failover and Starting the Observer. Initiate the failover on the standby database STAN: SQL>connect /@STAN as sysdba SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE FINISH; SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY; 2. In a complete failover, it is also possible to failover to a standby database (terminal standby) that gets redo from another standby database (cascader). This guide uses the naming convention of appending an underscore followed by a letter to the db_name to create the db_unique_name. files to automate tasks that must be performed before and after a fast-start failover The state file is locked when the observer is running to prevent multiple observers from using the same file. However, failover is attempted if the ObserverOverride configuration property is set to TRUE. 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. Now let's test switchover in the other direction. (It is permissible to change the RedoRoutes property on all standby databases including target standby databases. When enabled, re-create the standby database. the current working directory, Uses standard output for displaying the observer logs. Fast-start failover will not be attempted for the other types of database shutdown (NORMAL, IMMEDIATE, TRANSACTIONAL). connectivity with target standby. SQL>select sequence#, applied from v$archived_log; Verify the configuration from both hosts. 4. database that has the least amount of unapplied redo (smallest apply lag). The broker disables all of the physical and snapshot standby databases in the configuration. The minimum value of ObserverPingInterval is 100 If the protection mode was at maximum availability or maximum performance, it remains unchanged. Relationship Between Primary, Target Standby, and Observer During Fast-start Failover. It will return PHYSICAL STANDBY, The broker will not allow a switchover to a standby that has an apply delay configured (DelayMins property is set to a non-zero value). Valid values are >= 10. Oracle Data Guard helps you change the role of databases between primary and standby using either a switchover or failover operation. Instead, it allows an observer that is monitoring the configuration to initiate a fast-start failover should database conditions warrant a failover. When DGMGRL starts, if the DG_ADMIN Whether you reinstate or re-create a database depends on whether you performed a switchover or failover, on the type of standby database that was the target of the operation, and on whether or not there are sufficient flashback logs. Create a pre-callout script, or a post-callout script, or both. After you click the Reinstate button, Cloud Control begins reinstating the database. You can use Cloud Control or DGMGRL, to perform either a complete (recommended) or an immediate failover. You can query the V$FS_FAILOVER_STATS view on the primary database to display statistics about fast-start failovers that have occurred on the system. In addition to setting the configuration protection mode to maximum performance, you will also need to ensure that the LogXptMode database property for both the primary and target standby database is set to ASYNC. See START OBSERVER IN BACKGROUND for more information In maximum protection mode, an automatic failover is always possible because the Any apply delay must be removed before beginning a switchover. If you cannot tolerate any loss of data, then ensure that the configuration protection mode is set to maximum availability or maximum protection. 3. To failover, connect to the standby database and use the DGMGRL FAILOVER TO db-unique-name command. The foundation of FSFO is Data Guard - a primary and at least one standby. In the following example, a service named sales is configured to be active in the PHYSICAL_STANDBY role on the primary database NORTH. there is a lost network connection, be aware that the observer may attempt a Now it will return PRIMARY. To change the FastStartFailoverTarget property to point to a different standby database, disable fast-start failover, set the FastStartFailoverTarget property, and reenable fast-start failover. Note: If you have just enabled archivelog mode, force an archive log creation ( alter system archive log current) to ensure that at least one archive log exists. You must manually re-create the database as a standby database and then reenable it. The OberverPingRetry property specifies the number of START OBSERVING [cfg_group_name] starts a new observer for each broker configuration in the specified group. Ensure this file cannot be read by unauthorized users. lag is less than or equal to the value specified by the Complete Failovers in Configurations Using Far Sync Instances. Table 6-1 Content of Default Directory for Client-side Files, Contains the observer configuration file that is used by session. If the primary or target standby databases lose connections to all backup observers, then the broker does not try to nominate a backup observer as the new master observer, and the broker reports that the configuration is not observed. The primary database can be reinstated if it had flashback database enabled. 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. Broker can be configured to initiate failover on any of the following conditions. See "Database Service Configuration Requirements" for additional information about how the broker interacts with Oracle Restart. The old Primary must have been running in flashback mode before the failover. The observe-only mode for fast-start failover enables you to test how fast-start failover will work in your environment. 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. 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. If the database is managed by Oracle Clusterware, broker does not open any pluggable 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. 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. under the $DG_ADMIN directory. Use the wrapper script to start the observer process when the observer host boots or to restart it if it dies. Just be sure to include a Flashback Database history check in the script to provide an option to abort if a failover would require a manual reinstate. It will also alert you to databases that have had Flashback Database disabled at some point after FSFO was enabled. This allows Data Guard to remain functional during maintenance periods when the application listeners are down. FB Page:https://www.facebook.com/dbahariprasath/? The playground: Oracle Data Guard Command-Line Interface Reference for more information about these broker commands. Broker will verify that the configuration meets all prerequisites before enabling FSFO and will report any problems it finds. A far sync instance or Zero Data Loss Recovery Appliance is not a database and therefore cannot be the target of a role transition. After the database has been re-created, enable broker management of the re-created standby database by using the DGMGRL ENABLE DATABASE command. Once an observer is started, no further user interaction is required. It can be useful to perform such queries because fast-start failovers are fully automated and can occur at any time. In fact, failovers are so reliable, fast, and simple that switchovers become the exception rather than the rule. Look for the desired data in the RAM. Use the VALIDATE STATIC CONNECT IDENTIFIER command to ensure the static services have been configured correctly. FastStart Failover Ensues: Disaster strikes the primary database and its network connections to both the observer and the target standby database are lost. Reset database properties related to Redo Apply services, such as DelayMins. *PATCH V3 0/6] ASoC: codecs: Add Awinic AW883XX audio amplifier driver [not found] <000701d8e7521f78bc05e6a340awinic.com> @ 2022-11-11 11:26 ` wangweidong.a 2022-11 . The following example displays the contents of the fast-start failover If you want to use one Oracle home to start multiple observers, with each observer monitoring a different fast-start failover configuration, use the FILE qualifier to specify a unique observer configuration file location for each configuration to be monitored. This table describes the optional database properties that you can set. Reinstating the Former Primary Database in the Broker Configuration for more information about reinstatement. For Maximum Availability environments, change this to synchronous. See the "DISABLE FAST_START FAILOVER" command in Oracle Data Guard Command-Line Interface Reference for more information.
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