After the failover completes, the former primary database is automatically reinstated as a standby database when a connection to it is reestablished, if the FastStartFailoverAutoReinstate configuration property is set to TRUE. The syntax for the optional definition of a broker configuration group is: The group definition section is optional. You can start the observer before or after you enable observers are registered, a directory named Starting Multiple Observers On a Single Host. Determine the number and size of the Online Redo Log files (ORLs). To avoid the overhead of recording every change to every block, Flashback Database takes a "fuzzy" snapshot every 30 minutes and only records the before-image block upon its first change since the last snapshot. You can switch over or manual failover to a bystander database. Install the DGMGRL command-line interface on the observer computer as described in Oracle Data Guard Installation. The master observer uses the value specified by either the DGConnectIdentifier or ObserverConnectIdentifier database properties to connect to the primary and fast-start failover target standby databases. Dataguard PDB level failover support for Multitenant Oracle 19c 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. present, you must start the observer manually using the following directory. The information shown by this command is the same as that shown by a SHOW OBSERVER command on each individual configuration. Data Guard broker publishes this service on each instance as it comes up and broker management of the instance is initialized: To patch an environment where the Observer is running and fast-start failover is enabled, follow these steps prior to applying the patch. configuration property specifies how frequently the observer To start a switchover using Cloud Control, select the standby database that you want to change to the primary role and click Switchover. 1. Subdirectories within In such a case, no attempt is made to transmit any unsent redo from the cascader to the terminal standby. Oracle 11g Physical standby data Guard Failover steps - Data Guard Part If the PreferredObserverHosts property is set for the current the observer was killed after the stall began, but before the failover timeout had elapsed). When the observer loses its connection to the primary database for a period of time greater than that specified by the FastStartFailoverThreshold property, it attempts a failover to the standby database. 3. The guide attempts to be operating system agnostic; however, some examples may contain platform specific elements such as path and file naming conventions. Now your old standby database is become primary database, it is highly recommended to consider immediate full backup of primary database. Bystander standby databases that are not disabled by the broker after the switchover will continue operating in the state they were in before the switchover. Therefore, the target standby never falls behind the primary If the observer is unable to regain a connection to the primary database within the specified time, and the target standby database is ready for fast-start failover, then fast-start failover ensues. However the target can receive redo from a far sync instance.). A simple example for *nix is provided below that will work with both releases. If a group name is not specified, then SHOW OBSERVERS alone is also a valid command. Change Standby to Primary Database. PDF Download Solutions Oracle Data Guard 11gr2 Administration Beginner S Guide Dataguard broker is used to automate monitoring and controlling standby setups. An observer is an OCI SHOW OBSERVERS [FOR fg_group_name ] shows information about observers for all configurations in the specified group. lag is less than or equal to the value specified by the Commands For Managing Observers on Multiple Configurations. Displays when the target standby database does not have all of the primary database redo data and the configuration is operating in maximum availability mode. Bystander standby databases may be disabled by the broker during the failover, and they must be reinstated or re-created before they can serve as standby databases to the new primary database. The Table 6-2 FS_FAILOVER_STATUS Column of the V$DATABASE View. See Oracle Data Guard Concepts and Administration for more information on using the ALTER SYSTEM FLUSH REDO statement. In this mode you will need to consider how much data loss is acceptable in terms of seconds and set the FastStartFailoverLagLimit configuration property accordingly. Immediately after issuing command in step 2, shut down and restart the standby instance STAN: After a failover, the broker publishes Fast Application Notification (FAN) events. Using the db_unique_name of each database as the Oracle Net alias is simple and intuitive. It will not be allowed to open in any event if fast-start failover is enabled. By default, the observer will initiate failover to the target standby if and only if ALL of the following are true: Oracle Database 11g Rel 1 introduced user configurable failover conditions that can trigger the observer to initiate failover immediately. (Note that the target standby cannot be a far-sync instance. Oracle Data Guard helps you change the role of databases between primary and standby using either a switchover or failover operation. Remote login is required, along with a password file, to allow the databases in a Data Guard configuration to connect to each other. Check the spelling of your keyword search. To maximize the benefits of FSFO, the observer should run on a different host than the primary and standby databases. Automatic failover for Autonomous Data Guard enabled Autonomous One is the master Ensure that the required permissions are granted to the DG_ADMIN In the previous article, we have seen switching the role of Primary and standby database and failover Primary role to Standby database manually. If a fast-start failover was initiated because the primary database had crashed or lost connectivity with the master observer and target standby database, then the master observer automatically attempts to reinstate the former primary database as a standby database, if the FastStartFailoverAutoReinstate configuration property is set to TRUE. On the Data Guard Failover Confirmation page, specify the type of failover that you want to perform: Complete: All available redo is applied on the standby database. The logs also contain other details about the actions that will be performed in case of a failover. Remember to check Flashback Database history before aborting the primary. Managed recovery process has been stopped between primary and standby database and standby becomes primary database. If the target is a snapshot standby database, the broker first converts the database to a physical standby 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. Which three are prerequisites for enabling fast-start failover? However, fast-start failover cannot occur when the target standby database is in an unobserved state. Oracle Data Guard work on two database roles Primary and Standby. Set the, Configure the connect descriptor with a single network name that is registered with a global naming service such as DNS or LDAP. The new primary database is opened in read/write mode and redo transport services are started. OBSERVER command, if this directory does not have the orapwd file=$ORACLE_HOME/dbs/orapw$ORACLE_SID. Data Guard switchover with dgmgrl - dba-oracle.com No two observers on the same Data Guard Broker configuration can have the same name. The observer does not attempt to reinstate the former primary database. The selected standby database that will be the fast-start failover target must receive redo directly from the primary database. The other configurations that are not required but they might make your fast-start failover go smoothly. occurred to the target standby database prior to disabling fast-start In this case, no attempt is made to transmit any unsent redo from the far sync instance to the target physical standby prior to converting the physical standby into a primary database. Each group that you define must have at least one 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. Notice that the former primary is now disabled. 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. It uses the connect identifier specified in the observer configuration file to locate the credentials for a broker configuration from the Oracle wallet. 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. Except for testing purposes, it is not recommended that you start more than one observer on the same host for a Data Guard broker configuration. A good method to determine Flashback Database storage requirements is to enable Flashback Database and observe the amount of storage it uses during several peak loads. If you intend to switch back to the original primary database relatively soon, you may allow the physical and snapshot standbys to remain disabled. A fast-start failover to the target standby database fails. Observer uses the value of the DGConnectIdentifier property to connect to and monitor the primary and target standby databases. Reenabling Disabled Databases After a Role Change describes how to do this. Initiate reinstatement by mounting the database. SQL> startup ORACLE instance started. command START OBSERVER IN BACKGROUND. Updates the broker configuration file to record the change in roles. After you click the Reinstate button, Cloud Control begins reinstating the database.
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