Create a unique connect alias for each database. The primary database, it attempts to disable fast-start failover on as many databases in the configuration with which it has a network connection. This is the recommended method for disabling fast-start failover. If failover is not possible for some reason, then the master observer will continue checking whether the standby database is ready to fail over. See Setting the Protection Mode for Your Configuration. The minimum detection time is 6 seconds, which is the default required permissions, the admin folder is created After a switchover completes, the broker preserves the overall Oracle Data Guard protection mode as part of the switchover process by keeping the protection mode at the same protection level (maximum protection, maximum availability, or maximum performance) it was at before the switchover. This not only saves time and minimizes problems by automating an otherwise manual process, it exercises your failover and DR procedures with every flip so that you know the FSFO configuration is sound and, in a real emergency, everyone knows what to do. You cannot create the standby DB system in a different AD from the primary DB system. Manual failover can be performed even if the pre-condition checks are not met. fsfo_postcallout are stored in the same location as You must set both Which three are prerequisites for enabling fast-start failover? The act of switching roles should be a well-planned activity. SQL>select sequence#, applied from v$archived_log; The minimum By default, both files are stored in $ORACLE_HOME/dbs. A complete failover is the recommended and default failover option. If they are isolated from each other, then you must first disable fast-start failover by using the FORCE option, and then stop the observer. They cannot be reinstated. alter database recover managed standby database cancel; Step:3 The below commands will help to bring up standby as primary. Guide to Oracle Data Guard Fast-Start Failover The following sections provide information about managing observers: How the Observer Maintains Fast-Start Failover Configuration Information, Patching an Environment When the Observer Is Running and Fast-start Failover Is Enabled. Time for action - using interfaces to monitor Data Guard; Other replication solutions and Data Guard; 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. There can be up to four You can manage observers through either the Oracle Data Guard Overview pages in Cloud Control or using DGMGRL commands. You may failover to a snapshot standby database. Use the FastStartFailoverTarget configuration property on the current primary database to specify one or more fast-start failover targets. Note that these properties only affect whether primary shutdown and automatic reinstatement are performed if a fast-start failover occurs because the primary crashed or was isolated from the observer and target standby database. this script is run before the fast-start failover is initiated. Oracle Data Guard helps you change the role of databases between primary and standby using either a switchover or failover operation. 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. LinkedIn:https://www.linkedin.com/in/hari-prasath-aa65bb19/ There can be up to four observers for a single Data Guard configuration. Set the, Configure the connect descriptor with a single network name that is registered with a global naming service such as DNS or LDAP. Whenever possible, you should switch over to a physical standby database: If the switchover transitions a physical standby database to the primary role, then: The original primary database will be switched to a physical standby role. Check the Undo tablespace Usage in Oracle, Exclude/Include option in EXPDP and IMPDP Datapump, Missing Dependencies Python Core / win32api, Stop the EXPDP/IMPDP Datapump Job in Oracle, Find the temp usage by sessions in Oracle, Create & grant permission to directory in Oracle, Check the Patch Applied to the Oracle Database. They rely on Oracle Data Guard for high availability databases, with a standby database running in a different availability zone. Log into the new primary and verify that the changes made it across. Regards, Narottam Tagged: dataguard dba rac Welcome! If you like a connect-time failover to survive across a data guard switchover, you need another way to do it. 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. The new standby database is a viable target of a failover when it begins receiving redo data received from the new primary database. Do not use Shared Server (formerly MTS) for Data Guard. If the switchover transitions a logical standby database to the primary role, then: The original primary database will be switched to a logical standby role. by the current operating system user who is running DGMGRL The subdirectories Then, If the DG_ADMIN environment variable is not set, or the Use the oraenv script provided by Oracle. You can also specify a list of ORA- errors that will initiate FSFO failover. If the primary database has multiple standby databases, then you can specify multiple fast-start failover targets, using the FastStartFailoverTarget property. If all the databases do not have the same values, SRVCTL attempts to override the values, which will fail on the physical standby database because it is open read-only. In a separate terminal session, verify the configuration. SQL>connect /@STAN as sysdba Any database that was disabled while multiple role changes were performed cannot be reinstated. Data Guard Broker Failover - DBA Genesis Support This allows Data Guard to remain functional during maintenance periods when the application listeners are down. Figure 6-1 shows the relationships between the primary database, target standby database, and observer during fast-start failover: Before Fast-Start Failover: Oracle Data Guard is operating in a steady state, with the primary database transmitting redo data to the target standby database and the observer monitoring the state of the entire configuration. For any work, queries and help. In previous releases, OCI and ODP.NET clients receive FAN notifications via Oracle Advanced Queuing (AQ). These conditions are described in the following table: Dictionary corruption of a critical database. 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. The broker reinstates the database as a standby database of the same type as the former standby database of the new primary database. If client-side ONS configuration is used, the client-side ONS configuration file must specify the hostname and port of the ONS daemon(s) of the primary database and each standby database. command START OBSERVER IN BACKGROUND. If a group name is not specified, then SHOW OBSERVERS alone is also a valid command. Clusterware: The broker notifies Oracle Clusterware to stop active If only a file name is The time interval starts when the observer first loses its connection to the primary database. If errors occur during the disable operation, the broker returns an error message and stops the disable operation. 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. 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. Performing a Manual Failover Task 1: Determine Which of the Available Standby Databases is the Best Target for the Failover, Performing a Manual Failover Task 2: Start the Failover, Performing a Manual Failover Task 3: Reset the Protection Mode, Performing a Manual Failover Task 4: Re-establish a Disaster-Recovery Configuration. Manual failover to the fast-start failover target can be performed without receiving an acknowledgement from the observer. For example, if the limit specified is 30 seconds (the default), FSFO guarantees that all transactions that committed prior to 30 seconds ago are preserved during failover. To stop a specific observer when there are multiple registered observers running, issue the following command: You can log into DGMGRL from any machine to stop an observer. computer, it automatically starts the observer when you enable lower detection times for primary database failures, you must you need to make the primary database available, first confirm that a If the switchover occurs to a physical standby database, and the former primary Data Guard Broker - Controls the creation and monitoring of Data Guard. 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. Log in as a test user and make some changes that won't impact other parts of the system. When you are experiencing network disconnections and you issue the DISABLE FAST_START FAILOVER FORCE command on the primary database or a standby database that does not have connectivity with the primary database, fast-start failover may not be disabled for all databases in the broker configuration. configuration named ConfigurationSimpleName. STOP OBSERVING, and SET SWITCHOVER command, and the databases are managed by Oracle Note the use of "/@" to login using the wallet. The observer is the third party in an otherwise typical primary/standby Data Guard configuration. db_domain . Step:6 But before enabling Flashback Database, you must enable Flash Recovery Area (FRA). Reinstatement of the failed primary database as a new standby database failed. What is true about data guard set up with fast-start failover (FSFO) in Oracle Cloud Infrastructure (OCI)? If necessary, you can shut down the primary or target standby database in a fast-start failover environment. Manual failover gives you control over exactly when a failover occurs and to which target standby database. miliseconds. Errors occurring for any other configuration members will not impede the switchover. 2. Oracle 11g Manual Data Guard Part-II - DBAtricksWorld.com Aug 2022 - Present6 months. Change the failover target to the standby being switched over to, Change the failover target to the desired standby. This can happen for either of the following reasons: A bystander standby database has applied more redo data than the new primary database itself had applied when it was a standby database. Starting the Observer as a Background Process Using Keep this trigger as simple and reliable as possible, limiting it to only what is absolutely necessary at the moment of role transition, since any failures at this point may affect availability. 1. See the Cloud Control online help for more information. Oracle Real Application Clusters Administration and Deployment Guide for more information about configuring FAN, FCF, and ONS on an Oracle Real Application Clusters (Oracle RAC) database. However, no additional data is applied on the standby database once you invoke the failover. If the Oracle Data Guard configuration is operating in maximum protection mode, the broker does not allow a switchover to occur to a logical standby database. STAN is now transitioned to the primary database role.Now your PHYSICAL STANDBY Database has become PRIMARY. callout configuration scripts fsfo_precallout and The broker disables all of the physical and snapshot standby databases in the configuration. The configuration must be operating in either maximum availability mode or maximum performance mode in order to be able to switch over to a logical standby database. There are configuration requirements that must be met in order to publish and properly handle FAN events generated as the result of a broker-managed failover. Application Continuity is supported for Oracle Data Guard switchovers to physical standby databases. Disabling Fast-Start Failover Using DGMGRL. How to reinstate the old Primary as a Standby after Failover in #Oracle SHOW OBSERVERS [FOR fg_group_name ] shows information about observers for all configurations in the specified group. The observer does not need to coordinate fast-start failover when fast-start failover is disabled, so the primary and target standby do not nominate a master observer until fast-start failover is enabled. Initiate the failover on the standby database STAN: Now that we know switchovers work, it's time to test failovers. Reinstate the original primary database to act as a standby database in the new configuration. Media Recovery - Once the restore is complete, recovery proceeds as a typical media recovery, applying redo from archived and online redologs and rolling back uncommitted changes with undo. The selected standby database that will be the fast-start failover target must receive redo directly from the primary database. configuration scripts and checks for errors or misconfigurations. The command SHOW FAST_START FAILOVER shows a list of registered observers and indicates which one is the master. Fast-Start Failover allows Data Guard to automatically failover to a previously chosen standby database without requiring manual intervention to invoke the failover. This section describes how to configure and verify each prerequisite. Standby databases that are disabled during switchover, manual failover, or fast-start failover will not be automatically reinstated. If there are physical or snapshot standby databases in the configuration and the switchover occurs to a logical standby database, you need to re-create those databases from a copy of the new primary database and then reenable those databases, as described in Reenabling Disabled Databases After a Role Change. Note: the FSFO observer version must match the database version. Add the SRLs. 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. You have done a failover to your Standby database so it becomes the new Primary. The Oracle Database 11g observer can make use of specific credentials, allowing the same wallet to be used for multiple observers with different SYS passwords. After step 1 finishes, Switch the original physical standby db STAN to primary role; SHOW ObserverConfigFile used to check the runtime property ObserverConfigFile. ORACLE instance shut down. This is cleared on both when the reinstatement has been completed. In the previous article, we have seen switching the role of Primary and standby database and failover Primary role to Standby database manually. Suppose you have a primary database, BOSTON, and a standby database, CHICAGO. Regardless of the method you choose, the broker coordinates the role transition on all databases in the configuration. Initiate the switchover on the primary database PRIM: A switchover is a role reversal between the primary database and one of its standby databases. Oracle Database 10g allows a different password file to be used as long as the SYS passwords are the same on the primary and standby. This section will help you get started with creating a wrapper script to automatically start and restart the FSFO observer. failure on the primary database. This list describes restrictions when fast-start failover is enabled. Then the STOP OBSERVER command can be issued successfully on the former master observer. Unlike the primary / standby interconnect, where bandwidth and latency are determining performance factors, the observer requires very little network bandwidth and is not overly latency sensitive, allowing the it to be placed practically anywhere a reliable connection is available. The broker first converts the original primary database to run in the standby role. Performing failover : Step 1: Check Standby Database role. MASTEROBSERHOST TO command. If you are performing an immediate failover, then the database role is changed to primary without applying any accumulated redo data. occur. The following steps all require the database to be in a mounted (not open) state. directory specified by this variable does not exist, or the directory does not have the Reference architectures for Oracle databases on Azure - Azure Virtual Be sure to include the Data Guard listener in the local_listeners database parameter. Observer sites monitor the fast-start failover environment. 1,000,000 block changes on a small set of blocks generates less Flashback Database history than 1,000,000 changes on a larger set of blocks. You can also switch the master observer hosts for a group of configurations to one specific host. How to Failover to a Standby Database Manually and Rebuild Data Guard Once you set these properties, their values persist through role changes during switchover and failover. fast-start failover operation, the observer checks if a fast-start failover More specifically, we can have an asynchronous second read-only Managed instance in the same or in a different region. Set the FastStartFailoverThreshold property to specify the number of seconds you want the observer and target standby database to wait (after detecting the primary database is unavailable) before initiating a failover. $DG_ADMIN directory. For this reason, you should first issue this command on the target standby database. You might, for instance, use this to allow the observer to monitor the databases using the same connect identifiers as the client applications. If block change tracking is enabled on the primary, and the target Do not attempt to reinstate the old primary database if an ORA-752 or ORA-600 [3020] error has occurred at the failover target. On Linux/Unix, the directory specified by the DG_ADMIN environment Tasks that must be performed before and after a fast-start failover 3. Choosing the standby database with the smallest transport lag can minimize the amount of data loss and in some cases, incur no data loss at all. on ob3-host and ob4-host will not Enabling fast-start failover and starting an observer process involves the following tasks. 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. observer name, host, whether it is the master observer, when it became the master 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. The new ConfigurationWideServiceName configuration property can be used to simplify setting up this connect identifier. On the new primary database STAN, perform a SWITCH LOGFILE to start sending redo data to the standby database PRIM. If the Cloud Control agent is installed on the observer FSFO builds upon a number of other Oracle technologies and features such as Data Guard, Flashback Database, and Data Guard Broker. Create a wallet and set the default username and password to the database's SYSDBA credentials (usually SYS). This can be compared to performing an RMAN restore of the datafiles from a backup taken prior to the specified SCN, but is much faster. A database in the primary role will not open until it has verified with the observer that it is still the primary. This method will disable fast-start failover on all databases in the broker configuration. The ObserverOverride and ObserverReconnect properties allow you additional control over the connection to the primary. Broker changes database parameters during startup and role transitions via ALTER SYSTEM commands. A trigger on the DB_ROLE_CHANGE system event can be used to update the naming service and, with the proper client cache TTL settings, clients can connect to the new primary very quickly. In this case fast-start failover cannot occur because the databases are not ready to failover. See the START OBSERVER After the patch has been successfully applied to all databases, take the following steps to enable fast-start failover and start the observer. The connect descriptor must contain the SERVICE_NAME parameter in either case. Manual Failover in Data Guard - ORACLE-HELP the primary database that failed or took longer than the time Now your old standby database is become primary database, it is highly recommended to consider immediate full backup of primary database. When you execute commands that affect multiple observers, if you have not specified a name and location for the observer configuration file, then broker searches the current working directory for a file named observer.ora. A normal shutdown uses SHUTDOWN NORMAL, SHUTDOWN IMMEDIATE, or SHUTDOWN TRANSACTIONAL. The standby VM (myVM2) has the Oracle software installed only. The Column Value in the following table is consistent across instances in an Oracle Real Applications Clusters (Oracle RAC) environment.