data guard failover steps
data guard failover steps
The pre-callout script This is typically done for planned maintenance of the primary system. It comes with a GUI and command line interface. Fast-Start Failover in Oracle 11g Data Guard - Database Journal This file SQL> Select Database_role from v$Database; Application Continuity is supported for Oracle Data Guard switchovers to physical standby databases. Subdirectories within configuration property specifies how frequently the observer A switch-over allows the primary database to switch roles with its standby database. There can be up to four observers for a single Data Guard configuration. The following example displays the contents of the fast-start failover This property allows you to specify a priority ordered These scripts must be in the same directory as the Oracle Database 11g observers are incompatible with 10g databases and vice-versa. 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. Broker maintains these parameters by issuing ALTER SYSTEM commands as appropriate during role transitions, database startup/shutdown, and other events. primary, only the observers specified in the property can be use in the SET The FORCE option may be the preferred method for disabling To maintain a viable disaster-recovery solution in the event of another disaster, you may need to perform additional steps. Reinstatement restores high availability to the broker configuration so that, in the event of a failure of the new primary database, another fast-start failover can occur. Enabling fast-start failover and starting an observer process involves the following tasks. Observer uses the value of the DGConnectIdentifier property to connect to and monitor the primary and target standby databases. fast-start failover when: A network outage isolates the primary database from the observer and the target standby database before conditions exist that warrant a failover. Verifies that the target standby database is enabled. 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. 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. You must manually re-create the database as a standby database and then reenable it. Oracle Database 11g FSFO adds support for Maximum Performance mode (async redo transfer), providing the flexibility to trade durability for performance. Note the following points about the observe-only mode: The primary database can enter UNSYNC or LAGGING state without an acknowledgement from the observer or target standby. Thus, the validity of the values of these properties is not verified until after the switchover. The minimum See the Oracle Reference and Data Guard Administrator guides for your release for details. 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. . Issue the DISABLE FAST_START FAILOVER command or the DISABLE FAST_START FAILOVER FORCE command. Regardless of the method you choose, the broker coordinates the role transition on all databases in the configuration. A switchover guarantees no data loss and is typically done for planned maintenance of the primary system. status before the crash. You can find detailed information about all observers, including master observers and backup observers, in the V$FS_FAILOVER_OBSERVERS view. 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. LinkedIn:https://www.linkedin.com/in/hari-prasath-aa65bb19/ START OBSERVING [cfg_group_name] starts a new observer for each broker configuration in the specified group. This may result in two databases in the configuration simultaneously assuming the primary database role. The command SHOW OBSERVER provides detailed information about registered observers. Expected output is shown in blue text. A value of TRUE helps to ensure that an isolated primary database cannot satisfy user queries. Switch-over steps: Step-A: Shutdown primary database: SQL> shut immediate; Database closed. WAIT option, broker waits for the amount of Prerequisites for Enabling Fast-Start Failover provides complete information about all of the fast-start failover and reinstatement requirements. 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. Improper Oracle Net configuration is a leading cause of reported FSFO issues. To protect the files, it's good practice to store them in separate filesystems. Currently, this state can be detected only when the database is open. In case of worst situation with data guard primary database, or not available for production than we can activated standby database as a primary production database. A far-sync instance cannot be used in maximum protection mode. SQL>SHUTDOWN IMMEDIATE; Disaster Recovery with Oracle Data Guard - online presentation (Snapshot standbys are not included in the table because they are not supported as fast-start failover targets.). Reconnect within the time specified by the FastStartFailoverThreshold property. This article - the seventh in this ongoing . Follow Smart way of Technology on WordPress.com. Oracle 12c-Step by Step Manual Data Guard Switchover, Manual Upgrading Oracle Database From 11.2.0.4 to 12.2.0.1, Automatically Terminated The Blocking Session By Setting MAX_IDLE_BLOCKER_TIME, Apply Patching On Oracle 21c Database Release Update 21.7.0.0.0, Oracle 21c Point In Time Recovery of Pdb Database, Oracle 21c Cloning a PDB Database Using Sqldeveloper Tool. 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. If there is only one standby database in the configuration, you can skip this step and continue with Task 3. It is then started and stopped on the primary database. Select name,open_mode,database_role from v$database; Step:2 Cancel the MRP process Switchover and Failover with DataGuard Broker on Oracle 19c - Data Alchemy ConfigurationSimpleName is created. It is also supported for fast-start failover to physical standbys in maximum availability data protection mode. broker configuration, you must connect through another DGMGRL client After Fast-Start Failover: The fast-start failover has completed and the target standby database is running in the primary database role. An immediate failover should only be performed when a complete failover is unsuccessful or in the error cases just noted. files include the observer configuration file (observer.ora), observer log Application Continuity is an Oracle Database feature that enables rapid and nondisruptive replays of requests against the database after a recoverable error that made the database session unavailable. All database connections associated with the observer, including the initial connection, must use dedicated server connections. It's good practice to use separate listeners for application connections and Data Guard connections. 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 a switchover using Cloud Control, select the standby database that you want to change to the primary role and click Switchover. commands. Goal. Default value is 10 miliseconds. You must determine which available standby databases should be targets for failover. Add the SRLs. When performing a switchover in a configuration whose standby databases are This specifies how often the observer establishes a new connection to the primary database. 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. 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. Else, broker restarts the new Reinstating the Former Primary Database in the Broker Configuration for more information about reinstatement. 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. All physical and snapshot standby databases will be disabled and must be re-created from a copy of the new primary database after a switchover to a logical standby database. The observer host is 'observer.demo.org'. The values that indicate FSFO is ready for failover are listed below. environment variable to specify the default location for client-side broker files. Dataguard broker is used to automate monitoring and controlling standby setups. Choosing a Target Standby Database for Switchover and Choosing a Target Standby Database for Failover provide guidelines to help you choose a target 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. 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. This brings up the General Properties page that provides a Reinstate button. Fast-start failover can be used only in a broker configuration and can be configured only through DGMGRL or Cloud Control. The RedoRoutes property on the primary if the new value would result in the primary not being able to ship redo to the current fast-start failover target standby. The real test of the configuration is a successful role transition in both directions with both switchover and FSFO failover. For information about enabling fast-start failover, see Enabling Fast-Start Failover. For each broker configuration on which one or more Your email address will not be published. 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. The primary database, it attempts to disable fast-start failover on as many databases in the configuration with which it has a network connection. RAM). 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. under the $DG_ADMIN directory. If the protection mode was at maximum protection, it is reset to maximum performance. The Appendix provides information oncreating a simple wrapper script to start the observer as a background process. When using Maximum Availability mode, consider lowering this to reduce the time commits block when the standby becomes unavailable. broker opens all the PDBs on the new primary database and on the target standby In a manual failover, you convert a standby database to a primary database because the original primary database failed and there is no possibility of recovering the primary database in a timely manner. Theoretically, this method can be used when a data guard failover occurred between the primary and standby database, but not a switchover. Data guard Configuration details:- Login in to Standby Server:- Step:1 Check the database role and open_mode Select name,open_mode,database_role from v$database; command does not have a network connection to the primary database. A switchover is a role reversal between the primary database and one of its standby databases. If no value is specified for the 3. Now that we know switchovers work, it's time to test failovers. callout configuration scripts fsfo_precallout and STANDBY>connect /@STAN as sysdba Now it will return PRIMARY. Set the ObserverPingInterval and After step 3 completes, you can open the new Primary database STAN: the current working directory, Uses standard output for displaying the observer logs. The following conditions apply when multiple observers are registered for one configuration: When fast-start failover is enabled, one of the observers is the master observer. This walkthrough uses Maximum Availability mode to achieve "zero data loss". To stop the observer when fast-start failover is disabled, the primary database must be running. If possible, confirm that fast-start failover has not Use the FastStartFailoverTarget configuration property on the current primary database to specify one or more fast-start failover targets. Without the credentials, Broker will complete the role transition, but will leave the databases in need of a manual restart. Note: if the observer loses contact with the primary, but the standby does not, the observer can determine that the primary is still up via the standby. Updates the broker configuration file to record the change in roles. 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. Staff support, hardware and software, security (both software and site), network connections, and bandwidth should be equivalent at both sites. You can register up to four observers to monitor a single Data Guard broker configuration. In Maximum Availability mode, FSFO guarantees that no transaction that has received a commit acknowledgment will be lost during a failover. For more details about managing redo transport services using database properties, see Managing Redo Transport Services. Oracle 11g Manual Data Guard Part-II - DBAtricksWorld.com A failover to a physical standby database is preferable because it is likely that all standby databases in the configuration will still be available as standby databases to the new primary database after the failover operation completes. It's a good idea to have at least two hosts configured to run observers so that one can take over if the other fails. Use the 'show fast_start failover' command to see which user configurable FSFO failover conditions are in effect. To verify this change, again query the Database_role column of V$DATABASE. This will signal the observer to initiate failover after the FSFO threshold timeout has been reached (default is 30 seconds). This means that in order for a flashback database operation to succeed, observer and the standby both lose contact with the primary. 2) Switchover/Failover option is disabled on Enterprise Manager.What are the steps to enable it so that I can do Switchover/Failover operation using OEM. There are normally two situations when this operation will be performed: a planned outage for maintenance of the primary database or disaster recovery. To optimize the log apply rate: Do not configure the DelayMins database property to delay applying archived redo log files to the standby database (see Managing Log Apply Services for more information). Flashback Database is a continuous data protection (CDP) solution integrated with the Oracle Database. When a switchover is started, the primary and standby databases that are involved should have as small a redo lag as possible. There are many examples, and Ritesh Chhajer offers this example of doing a Data Guard switchover using dgmgrl: 1. Make sure that your OS environment on the standby is setup. milliseconds. 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. 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. milliseconds and that of ObserverRetryCount is 10. callout directory. This is normal. Issue the following commands on Primary database and Standby database to find out: 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. This section will help you get started with creating a wrapper script to automatically start and restart the FSFO observer. The minimum value of ObserverPingInterval is 100 FS_FAILOVER_OBSERVER_HOST shows the name of the computer on which the master observer is running, FS_FAILOVER_OBSERVER_PRESENT shows whether or not the master observer is connected to the local database. switch does not happen until the next time the primary contacts the target standby, 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. DNS CNAME) that always resolves to the primary. Tailing the alert logs on the primary and standby is a good way to watch Broker in action and get familiar with how it performs various tasks. Then, on the Fast-Start Failover Change Mode page, click Enabled. Failover automation ensures a seamless transition from the primary database to a synchronized standby database in cases of failure, while ensuring database availability by replaying uncommitted in-flight transactions. The broker first converts the original primary database to run in the standby role. configuration property. If the configuration contains physical, snapshot, and logical standby databases, consider choosing a physical standby database as the target standby database. The general approach seems to be CDB level failover to standby , so the failover takes place at CDB to CDB , in an event where a single PDB is experiencing an issue , we will have to failover the whole instance ..this will impact all PDB's on the CDB. These are the actions the broker performs after you start a switchover. The database on which the procedure is called notifies the observer. 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. These clients can be configured for Fast Connection Failover (FCF) to automatically connect to a new primary database after a failover. Dataguard switchover and failover steps in Oracle Immediately after issuing command in step 2, shut down and restart the former primary instance PRIM: If any errors occur during either conversion, the broker stops the switchover. Now it will return PRIMARY. 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. What to do in case of failover: (Important note: Istanbul is the primary server and Baku is the standby server) 1. If both HVR and Data Guard were running without latency or if no changes were made to the source database at the time of the failover, it can be assumed that all databases are synced and the no extra steps are necessary; the steps for Graceful Failover can be followed. Therefore, the detection time can be reduced to nearly This is particularly useful when registering with multiple listeners where the parameter value would otherwise exceed the 255 character limit. SQL> select name,open_mode,database_role from v$database; NAME OPEN_MODE DATABASE_ROLE --------- -------------------- ---------------- MYTEST MOUNTED PHYSICAL STANDBY Step 2: Apply the following command to finish database recovery. To enable fast-start failover in Cloud Control, use the Fast-Start Failover wizard. Running a StatusReport on the primary should verify that the error is due to a missing observer. (as it might in maximum availability and maximum performance modes). See the START OBSERVER Table 6-2 FS_FAILOVER_STATUS Column of the V$DATABASE View. The guide attempts to be operating system agnostic; however, some examples may contain platform specific elements such as path and file naming conventions. It has two parts in the following order: Configuration declaration this section is mandatory. Archiver is unable to archive a redo log because the device is full or unavailable. A simple example for *nix is provided below that will work with both releases. cannot use a different name for this file. FastStartFailoverLagLimit configuration property is set to zero) or If fast-start failover is enabled, then a switchover can be performed only to the pre-specified target standby database and only if the standby database is synchronized with the primary database or is within the configured lag limit, for the max availability and max performance modes respectively. If you re-create the old primary database, it must be created as the standby type of the old standby database. When the standby becomes available again, the primary and standby re-synchronize and resume synchronous redo transfer. The broker selects a target based on the order in which they are specified on the FaststartFailoverTarget property. drain_timeout amongst the active services. The target standby database has contact with the primary database. 3. 12c upgrade, The below commands will help to bring up standby as primary, https://www.linkedin.com/in/hari-prasath-aa65bb19/, https://www.facebook.com/groups/894402327369506/. Moorestown, New Jersey, United States. Immediate Failovers in Configurations Using Far Sync Instances. If the observer finds that the database is no longer the primary, it will attempt to reinstate it as the failover target standby. Errors occurring for any other configuration members will not impede the switchover. If fast-start failover is disabled, then manual failover may still be possible. FastStartFailoverLagLimit ConfigurationSimpleName represents Your email address will not be published. Enable Fast-Start Failover Using Cloud Control. miliseconds. In the rare event that a switchover operation fails and you are left with no primary database, retry the switchover command.