command is submitted successfully, the command-line prompt on the broker does not allow the primary database to commit transactions until it has regained 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. The targets are referred to as candidate targets. Connect-Time Failover to Standby Database - Ed Chen Logic When a primary loses contact with both the failover target and the observer simultaneously, it enters a "stalled" state (v$database.fs_failover_status = 'STALLED') and any sessions still connected to the primary will block on commit. Broker will set the primary to use asynchronous log transport by default. It will not be allowed to open in any event if fast-start failover is enabled. Fast-start failover will not be attempted for the other types of database shutdown (NORMAL, IMMEDIATE, TRANSACTIONAL). Verify dmon process is running and broker parameters viz. 2. Database dismounted. Set the ObserverPingInterval and created under this directory by DGMGRL will also have the same permissions. fast-start failover, you can issue the DGMGRL SHOW FAST_START FAILOVER, /home1/dataguard/config_NorthSales/callout/fsfocallout.ora. Dataguard PDB level failover support for Multitenant Oracle 19c In Maximum Availability mode, FSFO guarantees that no transaction that has received a commit acknowledgment will be lost during a failover. If the DG_ADMIN environment variable is not set, or the Immediate Failovers in Configurations Using Far Sync Instances. Observer uses the value of the DGConnectIdentifier property to connect to and monitor the primary and target standby databases. return until you issue the STOP OBSERVER command Oracle Data Guard configuration with DGMGRL. This page will not allow you to alter the protection mode. It uses the connect identifier specified in the observer configuration file to locate the credentials for a broker configuration from the Oracle wallet. If the primary database has multiple standby databases, then you can specify multiple fast-start failover targets, using the FastStartFailoverTarget property. Data Guard broker does not manage or store credentials. The connect descriptor can be configured in one of two ways: Oracle Database PL/SQL Language Reference for more information about the DB_ROLE_CHANGE system event. The price for this guarantee is increased commit latency ( log file sync waits). To failover, connect to the standby database and use the DGMGRL FAILOVER TO db-unique-name command. ob2-host can be a master observer when time specified in the WAIT option. US Coast Guard Auxiliary. 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. Tags: Data Guard, Oracle. Once an observer is started, no further user interaction is required. the names of the scripts created in the previous step. Open another prompt and connect to SQLPLUS: Set both these properties to achieve a primary failure detection time of 1 The broker preserves the protection mode that was in effect prior to the failover. Slightly less critical than making sure you've got a good primary is making sure the failed primary can be automatically reinstated. Oracle Database 11g adds the ObserverConnectIdentifier database property to the Broker configuration, allowing you to specify a connect identifier for the observer to use for monitoring the primary and failover target. 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. committing because a fast-start failover may have occurred while it was This is cleared on both when the reinstatement has been completed. When fast-start failover is enabled, the broker determines if a failover is necessary and initiates the failover to the current target standby database automatically, with no need for manual intervention. Make sure that xdpyinfo exist under PATH variable. They must be re-created before they can serve as standby to the new primary database. If the Broker configuration is changed to make a bystander the new failover target (probably a good idea if the failed database will be down for a while), the observer will not automatically reinstate the former primary because it is no longer part of the FSFO 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. To see Manual Switch Over Manual SwitchOver in Oracle To see Manual Fail Over Manual Failover in Data Guard With Oracle Data Guard [] Default value is 100 Contains the observer runtime data file for the broker observer as a foreground process. an alias of the broker configuration name. 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. A manual failover is already in progress. (as it might in maximum availability and maximum performance modes). Therefore, the primary database can continue processing transactions, even if the target standby database fails. Both Cloud Control and the DGMGRL CLI will do this automatically as part of failover. occurred to the target standby database prior to disabling fast-start The following is an example of setting the LogXptMode property: Alternatively, use the RedoRoutes property to set the redo transport mode for the target standby and database that is currently in the primary role. Transitions the target standby database into the primary database role, as follows: Changes the role of the database from standby to primary. You may failover to a snapshot standby database. They cannot be reinstated. Once an immediate failover is started, the broker: Verifies that the target standby database is enabled. Cancel MRP process. Instead, Oracle Clusterware opens PDBs on particular instances based on A switchover is a role reversal between the primary database and one of its standby databases. Broker is a Data Guard management utility that maintains state information about a primary and its standby databases. Reconnect within the time specified by the FastStartFailoverThreshold property. database. To verify this change, again query the Database_role column of V$DATABASE. These Oracle Data Guard Concepts and Administration provides information about setting up the databases in preparation of a switchover. stored in the specified path using the default file names. Oracle Data Guard can switch a standby database to the primary role in case a production database becomes unavailable due to . (Note that the target standby cannot be a far-sync instance. This exercises the configuration, but triggers failover differently than losing contact with the primary. You can use this information to identify ahead of time any redo transport configurations that would be incorrect after a role change, including any standbys that will not receive redo because the RedoRoutes property was not configured correctly. select name,open_mode,database_role from v$database; Note: Unlike ORLs, SRLs should be created with only one member per group. You can use the maximum protection, maximum availability, or maximum For systems with multiple RAID controllers, consider creating SRLs such that their IO is balanced across the controllers. Click Failover. created when the START OBSERVER command is issued. Once fast-start failover is enabled, the broker will ensure that fast-start failover If a non-zero value is specified for the Do not use Shared Server (formerly MTS) for Data Guard. This section describes how to stay on top of your FSFO environments. The master observer cannot connect to the target standby database, What Happens if the Observer Fails? PDF Steps To Configure Oracle 11g Data Guard Physical Standby 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. If the failover fails for any reason, it could leave the target standby database inoperable, regardless of whether the target standby database is ready to failover. The ObserverPingInterval When the conditions for fast-start failover are met, the Broker adds messages to the observer log and broker log indicating that fast-start failover would have been initiated. These scripts must be in the same directory as the environment variable must have exclusive permissions wherein it can be accessed only If you are performing a complete failover, then all accumulated redo data is applied before the database role is changed to primary. Without the credentials, Broker will complete the role transition, but will leave the databases in need of a manual restart. The log file name is specified with the LOGFILE IS option of the START OBSERVER command. The terminal session will appear to hang at this point. The primary database can be opened even if there is no acknowledgement from the observer or target standby. 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. Automatic failover quickly and reliably fails over the standby Autonomous database to the primary database role, without requiring you to perform any manual steps. To get started, all you'll need is Oracle Database Enterprise Edition Release 10.2 or later, a database, and three hosts: two for the databases and a small host for the FSFO observer. If Flashback Database history is insufficient, the observer will not be able to reinstate and you will have to manually reinstate from backup or by primary duplication. If you intend to switch back to the original primary database relatively soon, you may allow the physical and snapshot standbys to remain disabled. You cannot perform a manual failover to the target standby database for the same reason. The following steps all require the database to be in a mounted (not open) state. Figure 6-2 shows the observer monitoring a fast-start failover configuration. Even if you have successfully connected to a database server in the broker configuration using the CONNECT command, this command ignores the existing connection and uses the credentials stored in Oracle wallet. The broker interacts with Oracle Clusterware or Oracle Restart to ensure that the appropriate database services are active and that the appropriate FAN events are published after a role change. 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. Each observer is identified by a name that you supply when you issue the START OBSERVER command. Don't initiate failover unless at least 30 minutes of history is available. (See Disabling Fast-Start Failover for important considerations when using the FORCE option.). You can start the observer before or after you enable Overall Steps:-. The following sections provide more information about the fast-start failover environment: When Fast-Start Failover Is Enabled and the Observer Is Running, Restrictions When Fast-Start Failover is Enabled, Shutting Down the Primary Database When Fast-Start Failover Is Enabled, Performing Manual Role Changes When Fast-Start Failover Is Enabled. LGWR is unable to write to any member of the log group because on an I/O error. configuration named ConfigurationSimpleName. If you are performing an immediate failover, then the database role is changed to primary without applying any accumulated redo data. Broker changes database parameters during startup and role transitions via ALTER SYSTEM commands. You must also start and stop the SALESRO service on the primary so that it can be started on the standby. In the event of a Oracle Data Guard Broker is a utility that can help you manage your Oracle Data Guard. Perform SWITCH LOGFILE if necessary. This list describes how the overall Oracle Data Guard protection mode is handled after a manual failover (complete or immediate). When both databases have been restarted, you may restart the observer. on ob3-host and ob4-host will not Oracle Data Guard Manual Failover - ORACLEAGENT BLOG 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. Configure Data Guard Broker to manage and monitor the Data Guard configuration. The existence of a .suc file, flashback logs on that database. The word ALL cannot be used as a group name because it is a reserved keyword. broker configuration, you must connect through another DGMGRL client Add the wallet location and override to sqlnet.ora. 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. The previous examples dealt with setting up only one service on a database. Read-Only Standby and Active Data Guard FSFO enabled configurations having multiple standbys cannot switchover to a standby that is not the failover target. The target standby database has contact with the primary database. If this is an Oracle RAC physical standby database managed by Oracle Clusterware, then the broker directs Oracle Clusterware to restart the new standby database. The new primary database starts transmitting redo data to the new standby database. You can register up to four observers to monitor a single Data Guard broker configuration. Be sure to include the Data Guard listener in the local_listeners database parameter. Transitions the target standby database into the primary role, opens the new primary database in read/write mode, and starts redo transport services. If it's not, DGB will not allow the failover to continue until the DBA has manually resolved any discrepancies. For example, to determine if fast-start failover can occur, the FS_FAILOVER_STATUS column displays either SYNCHRONIZED or TARGET UNDER LAG LIMIT and the FS_FAILOVER_OBSERVER_PRESENT column displays YES for the target 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. It is then started and stopped on the primary database. In order to maintain separation of Broker and non-Broker activity, a second static service is recommended. 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. through these services to exit or for the specified wait time Broker will verify that the configuration meets all prerequisites before enabling FSFO and will report any problems it finds. When using DGMGRL, you need to issue the SWITCHOVER command, specifying the name of the standby database that you want to change into the primary role. If the status is SUCCESS, you're ready to start testing role transitions. November 20, 2009. database that has the least amount of unapplied redo (smallest apply lag). In this case, the observer cannot perform a fast-start failover even if conditions warrant a failover. The minimum value is 100 milliseconds. under the $DG_ADMIN directory. When you configure data guard using OCI console, the default mode is set to maxprotection. The environment is a single instance database without any grid Infrastructure components. Some properties have changed between those releases. failure on the primary database. Subsequent changes to the same block during the same snapshot are not recorded. Note: Data Guard requires dedicated server connections for proper operation. Data Guard Physical Standby Setup in Oracle Database 11g Release 2 It shuts down or stalls because it is likely a failover has occurred. FSFO builds upon a number of other Oracle technologies and features such as Data Guard, Flashback Database, and Data Guard Broker. If the configuration contains both physical and logical standby databases, consider choosing a physical standby database (that has the least amount of unapplied redo) to be the target standby database. Provides an automatic failover alter database recover managed standby database cancel; Step:3 The below commands will help to bring up standby as primary. You can use Cloud Control or DGMGRL, to perform either a complete (recommended) or an immediate failover. observer. The configuration and database status report the same error messages as are returned when there is only one registered observer. 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. They must be re-created from a copy of the new primary database. In a complete failover, it is also possible to failover to a standby database (terminal standby) that gets redo from another standby database (cascader). Fast-Start Failover in Data Guard Environments on Oracle Cloud 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. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. In the previous article, we have seen switching the role of Primary and standby database and failover Primary role to Standby database manually. Reinstate the original primary database to act as a standby database in the new configuration. If the former primary database cannot be reinstated automatically, you can manually reinstate it using either the DGMGRL REINSTATE command or Cloud Control. SQL>select sequence#, applied from v$archived_log; Its primary job is to perform a failover when conditions permit it to do so without violating the data durability constraints set by the DBA. The required attributes vary depending on your configuration (including whether your environment is Oracle RAC-based or single-instance). DGMGRL> show configuration Configuration - CDB01_fraad1_CDB01_fraad3 Protection Mode: MaxAvailability Members: CDB01_fraad1 - Primary database CDB01_fraad3 - (*) Physical standby database the Steps To Congure Oracle 11g Data Guard Physical Standby associate that we give here and check . fast-start failover. Make sure the last redo data transmitted from the Primary database was applied on the standby database. Oracle 12c-Step by Step Manual Data Guard Failover. To see the specific parameter, use the "show database StatusReport" command. For Oracle Database Release 12.2 and higher, Oracle Enterprise Manager Cloud Control (Cloud Control) supports configuring multiple observers using the Enterprise Manager Command Line Interface (EM CLI). This action may result in two databases in the configuration simultaneously assuming the primary database role. See Installing and Starting the Observer. Credentials Required for Access to Broker Configurations. After fast-start failover is enabled and up to four observers are started, one observer is nominated as the master observer that continuously monitors the environment to ensure the primary database is available. The simple tests described in this guide are fine for making sure the basics are working, but you'll probably want to develop a more comprehensive set of tests suited to your environment and requirements. The standby database must be re-created or reinstated before it can serve as a standby for the new primary database. Here's a one-liner observer startup for *nix. There may or may not be data loss depending upon whether your primary and target standby databases were synchronized at the time of the primary database failure. For example, if all your physical standbys are also unavailable, then failing over to a logical standby is your only choice. See Enabling Fast-Start Failover for more information. times that the observer retries a failed ping before it initiates a . Standby databases that are disabled during switchover, manual failover, or fast-start failover will not be automatically reinstated. The observer automatically starts the reinstatement process. directory does not have the required permissions, broker does the following: When you run DGMGRL commands, if a path and file name are explicitly specified for Reference architectures for Oracle databases on Azure - Azure Virtual The real test of the configuration is a successful role transition in both directions with both switchover and FSFO failover. Verify the primary database instance is open. You can manage observers through either the Oracle Data Guard Overview pages in Cloud Control or using DGMGRL commands. If the database is not managed by Oracle Clusterware, Reinstatement is supported only after failover in a broker configuration. variable must have read, write, and execute permissions for the directory owner This function can be called from a connection to either the primary or any standby in the configuration. For Active Oracle Data Guard, it will fail to open up a connection unless its in read-only mode. 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. 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). After setting local_listener, register the database with the listener and verify the services have been registered. You can specify STOP OBSERVER ALL to stop all observers registered in a broker configuration. Some of the statistics that can be monitored are as follows: LAST_FAILOVER_TIME that shows the timestamp of last fast-start failover, LAST_FAILOVER_REASON that shows the reason for the last fast-start failover. DGMGRL can be used to manage multiple observers in a group of broker configurations. How to Re-create and Reenable a Disabled Database. Starting Multiple Observers On a Single Host. But it will also continue trying to reconnect to the primary database indefinitely. The Appendix provides information oncreating a simple wrapper script to start the observer as a background process. Note that enabling FSFO does not make the configuration ready for automatic failover - that requires an observer, which we'll get to next. See Disabling Fast-Start Failover. STANDBY> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY; Broker stores it configuration information in a mirrored set of files outside the database. This file contains connect identifiers to both the primary and the target standby databases. It is possible to manually perform an immediate failover to a standby database that receives redo data from a far sync instance. Step 4: Enable Fast-Start Failover Now we are ready to enable FSFO: DGMGRL> enable fast_start failover; Enabled in Zero Data Loss Mode. must ping the primary database. post-callout script, and pre-callout success file for the broker In this case, only observers on ob1-host and It uses these databases as a copy of the . It comes with a GUI and command line interface. In this case, disable fast-start failover using the FORCE option on the target standby database. There is no impact on your current configuration or on applications. To start an observer as a background process, use the DGMGRL This list describes conditions in which the broker cannot automatically reinstate the former primary database. After the conversion, the broker will start Redo Apply to apply accumulated redo data, before failing the database over to the primary role. Application Continuity is supported for Oracle Data Guard switchovers to physical standby databases. Broker maintains these parameters by issuing ALTER SYSTEM commands as appropriate during role transitions, database startup/shutdown, and other events. 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. FAN events are always published through ONS. Using Shared Server (MTS) or connection pooling can result in unpredictable behavior. FastStartFailoverLagLimit property. 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. This configuration property causes the primary database to shut down if fast-start failover is enabled and V$DATABASE.FS_FAILOVER_STATUS indicates the primary has been STALLED for longer than FastStartFailoverThreshold seconds. 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. The broker reinstates the database as a standby database of the same type as the former standby database of the new primary database. PRIM>STARTUP MOUNT; Overview of Switchover and Failover in a Broker Environment. Remote login is required, along with a password file, to allow the databases in a Data Guard configuration to connect to each other. STANDBY>connect /@STAN as sysdba Synopsis. The default value is ALL. You can also switch the master observer hosts for a group of configurations to one specific host. A complete failover is the recommended and default failover option. The broker initiates a failover after the number of seconds specified by this operation can be automated using callout scripts. all of the same type (all physical or all logical standby databases), choose the standby The Column Value in the following table is consistent across instances in an Oracle Real Applications Clusters (Oracle RAC) environment. See Oracle Enterprise Manager Command Line Interface. See the Cloud Control online help for more information. When DGMGRL starts, if the DG_ADMIN Steps for FAILOVER the Dataguard environment The database cannot provide fast-start failover status information. time, if all the sessions that are connected though the active services Data Guard Broker Failover - DBA Genesis Support What is true about Data Guard setup with fast-start failover? The following assumes that the standby host has been setup according to Oracle's recommendations and that the operating system, accounts, security, resource limits, directory structure, etc. Set the, Configure the connect descriptor with a single network name that is registered with a global naming service such as DNS or LDAP. 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. Please contact us at contactus@smarttechways.com. fsfocallout.ora. In maximum availability mode, set the LogXptMode database property for both the primary and target standby databases to SYNC or FASTSYNC. 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. Click Disable in the Fast-Start Failover wizard. command START OBSERVER IN BACKGROUND. Add the SRLs. When enabled, re-create the standby database. Running a StatusReport on the primary should verify that the error is due to a missing observer. 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. The following table summarizes which standby types are supported in which protection modes when fast-start failover is enabled. It wouldn't be much of a test if we didn't verify that our durability constraints were being met, so let's make a change on the primary and see if it survives the failover. The value specified for either of these properties should allow the master observer to connect to any instance of an Oracle RAC database.