data guard failover steps data guard failover steps

times that the observer retries a failed ping before it initiates a Displays if the standby database's redo applied point lags the primary database's redo generation point by more than the number of seconds specified by the FastStartFailoverLagLimit configuration property and the configuration is operating in maximum performance mode. SQL>ALTER SYSTEM SWITCH LOGFILE; As described in theFlashback Database section, Flashback Database takes place in two stages: a restore stage and a media recovery stage. DNS CNAME) that always resolves to the primary. If fast-start failover is disabled, then manual failover may still be possible. If a group name is not specified, then SHOW OBSERVERS alone is also a valid command. See theFlashback Database section above for information on storage requirements. ConfigurationSimpleName. Create a script to automate FSFO failover initiation and use it as your standard method for standby flips. Tasks that must be performed before and after a fast-start failover required permissions, fast-start failover callouts will fail. START OBSERVING [cfg_group_name] starts a new observer for each broker configuration in the specified group. The targets are referred to as candidate targets. Careful consideration should be given before enabling fast-start failover for either of these conditions because doing so will supersede availability options provided by Oracle Clusterware. database's redo generation point by more than the value specified by the The terminal session will appear to hang at this point. SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY; For example: In the following example, assume the network between the primary database and the observer has failed. enabling fast-start failover. A fast-start failover to the target standby database fails. 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. Once you have completed the switchover back to the original primary, you may then reenable the physical and snapshot standby databases since they are still viable standbys for the original primary database. If no name is specified for the observer then a default observer name, the host name of machine where the START OBSERVER command is issued, is used. This walkthrough assumes that all ORLs and SRLs on the primary and standby databases are the same size. Aug 2022 - Present6 months. Use the oraenv script provided by Oracle. Starting with 11 is purely cosmetic - it allows new ORL groups to be added later while keeping their group# in the same sequence as the existing ORLs. 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. These clients can be configured for Fast Connection Failover (FCF) to automatically connect to a new primary database after a failover. Step-B: Copy control file to temporary location on primary database. When enabled, re-create the standby database. CONNECT command. Moorestown, New Jersey, United States. The following is an example of querying the V$FS_FAILOVER_STATS view: Disabling fast-start failover prevents the observer from initiating a failover to the target standby database. US Coast Guard Auxiliary. The steps in this section describe the tasks involved to perform a manual failover. On the Oracle Data Guard Overview page, click Database must be reinstated. Note that role changes to logical standby databases always result in physical standby database bystanders being disabled. After a failover, a bystander will not automatically become the new failover target. have received all the redo data the primary has generated in order for automatic failover to Application Continuity is supported for Oracle Data Guard switchovers to physical standby databases. In a DataGuard environment when the Primary instance fails you need to go through the Failover and Reinstate processes in order to restore the database service, as described in the documentation: Changes a standby database to the primary role in response to a primary database failure. For any work, queries and help. It uses the connect identifier specified in the observer configuration file to locate the credentials for a broker configuration from the Oracle wallet. 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. In Maximum Availability mode, FSFO guarantees that no transaction that has received a commit acknowledgment will be lost during a failover. If the agent is not If the configuration is not failable, the DBMS_DG.INITIATE_FS_FAILOVER function returns an ORA error number (it does not signal an exception) informing the caller that a fast-start failover could not be performed. 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. 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. If you cannot tolerate any loss of data, then ensure that the configuration protection mode is set to maximum availability or maximum protection. instructions for the DGMGRL command-line interface. No instances are shutdown when doing a failover, if the target standby database is either a physical or logical standby. In such a case, no attempt is made to transmit any unsent redo from the cascader to the terminal standby. The ObserverPingInterval Starting Multiple Observers On a Single Host. The following example displays the contents of the fast-start failover For this reason, you should first issue this command on the target standby database. You can specify STOP OBSERVER ALL to stop all observers registered in a broker configuration. configuration property specifies how frequently the observer This is called failover. Enable Fast-Start Failover Using Cloud Control. property. 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. standby database, host, or network failure, etc.). The drain_timeout is specified in the SRVCTL In the event of a The observer maintains state information in a file. primary database must have network connectivity. files are stored in subdirectories of the DG_ADMIN directory. 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. See Manual Failover for complete information about manual failovers. The primary database can be reinstated if it had flashback database enabled. Oracle Data Guard work on two database roles Primary and Standby. If you expect the network to be disconnected for a long time and They may be reinstated if Flashback Database is enabled on those databases. The only exception to this is failovers to snapshot standby databases. redo generation on the primary database will be stalled. The observer configuration file is a text file and the syntax to define observers and groups is similar to that used in the listener.ora or tnsnames.ora files. When the configuration has only one registered observer, if the primary and target standby databases stay connected but the connection to the observer is lost, then the broker reports that the configuration is not observed. If the primary and target standby databases do not have network connectivity or if the database to which you are connected does not have network connectivity with the primary database, consider using DISABLE FAST_START FAILOVER with the FORCE option. Example 6-2 Sample Observer Configuration File. It is also supported for fast-start failover to physical standbys in maximum availability data protection mode. collections and databases Set up replica sets and automatic failover in MongoDB Use sharding to scale horizontally, and learn how . So SALESRW will start on CHICAGO (which is now the primary) and SALESRO will start on BOSTON (which is now the physical standby). It can be useful to perform such queries because fast-start failovers are fully automated and can occur at any time. To configure fast-start failover in observe-only mode: Fast-start failover will not be triggered if the primary or standby database is shut down normally. Let's run the command on the primary database to validate if the environments are ready for the role transition : JITPRD> alter database switchover to JITSDB verify; alter database switchover to JITSDB verify * ERROR at line 1: ORA-16475: succeeded with warnings, check alert log for more details If that metadata is pushed out, Oracle can no longer find a fuzzy snapshot so it will not be able to flash back. 12c Dataguard, In 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. Otherwise, the DUPLICATE TARGET DATABASE command will fail with "RMAN-20208: UNTIL CHANGE is before RESETLOGS change". See Sources of Diagnostic Information for details about the broker's drc* log files. This support note is available at http://support.oracle.com. The behavior of the broker if the master observer fails depends on whether the broker configuration has one observer or multiple observers. For example, perform full level 0 backups weekly and incremental level 1 backups daily. Automatic failover is optional and can be enabled or disabled on your Autonomous Container Databases with Autonomous Data Guard. This section describes how to configure and verify each prerequisite. 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. The failover was to a logical standby database. 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. In order to maintain separation of Broker and non-Broker activity, a second static service is recommended. alter system set standby_file_management=auto; This parameter must be set before the primary can be opened in Maximum Availability mode. If you perform a manual failover when fast-start failover is enabled: The failover can only be performed to the current target standby database. In maximum protection mode, an automatic failover is always possible because the When using Maximum Availability mode, consider lowering this to reduce the time commits block when the standby becomes unavailable. Be sure to include the Data Guard listener in the local_listeners database parameter. If you want to capture any logging generated by the observer, use the LOGFILE IS option on the START OBSERVER command, and ensure that the file name is unique. configuration property. 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. Use the FastStartFailoverTarget configuration property on the current primary database to specify one or more fast-start failover targets. Verify there are no active users connected to the databases. db1_a: Alias to connect to the dynamic Data Guard service on database "a", db1_b: Alias to connect to the dynamic Data Guard service on database "b", db1_a_static: Alias to connect to the static Data Guard service on database "a", db1_b_static: Alias to connect to the static Data Guard service on database "b". The broker controls the rest of the switchover. configuration file, and fast-start failover callout script files. If this operation is successful, a zero data loss failover may be possible even if the primary database is not in a zero data loss protection mode. ORACLE instance shut down. It's generally a good idea to store the state file in a directory associated with the database to avoid locking issues when running multiple observers on the same host. On Windows, the directory specified by the DG_ADMIN Syntax for Mandatory Configuration Declaration. You must ensure that the primary database is shut down prior to performing a manual failover. Note that this does not guarantee no data will be lost. Conditions shown in blue are enabled by default. The foundation of FSFO is Data Guard - a primary and at least one standby. the Steps To Congure Oracle 11g Data Guard Physical Standby associate that we give here and check . The required attributes vary depending on your configuration (including whether your environment is Oracle RAC-based or single-instance). pre-callout configuration script and post-callout configuration script. After the restart, Redo Apply begins applying redo data from the new primary At a minimum, you must set db_unique_name. To stop an observer currently designated as the master observer, first issue the SET MASTEROBSERVER command to designate a different observer as master observer. Note that the database will not open at this point. Is possible if the target standby database displays SYNCHRONIZED and the FS_FAILOVER_OBSERVER_PRESENT column displays YES. the SYSDG or SYSDBA privilege. There is little risk in enabling Flashback Database to determine its storage requirements - it can be disabled while the primary is open if necessary. See Reenabling Disabled Databases After a Role Change. Another good test is to simulate network failures that leave the primary up, but isolated from the failover target standby and the observer. Once fast-start failover is enabled, the broker will ensure that fast-start failover Add the wallet location and override to sqlnet.ora. The role change is directed to the same standby database that was specified for the FastStartFailoverTarget database property on the primary database. Only two databases, the primary and the failover target, can be in the FSFO configuration at any given time. FastStartFailoverLagLimit configuration property. 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. from another DGMGRL session. The ObserverOverride configuration property, when set to TRUE, allows an automatic failover to occur when the observer has lost connectivity to the primary, even if the standby has a healthy connection to the primary. In order to accommodate all load conditions, Oracle recommends having at least one more SRL group than the number of ORL groups of the same size. The commands that can be executed for a group of configurations (as declared in an observer configuration file) are as follows. Observer uses the value of the DGConnectIdentifier property to connect to and monitor the primary and target standby databases. For information about event notification and database connection failover support for global services, see the Oracle Database Global Data Services Concepts and Administration Guide. 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. Note that primary and standby databases must be licensed for Oracle RAC or Oracle Active Data Guard in order to use Application Continuity. 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. See Manual Failover for information about manual failover. This list contains some recommendations to obtain better performance when using fast-start failover. The information in this guide is based on practical experience gained from deploying FSFO in a global corporate production environment. is only possible when the configured data loss guarantee can be FastStartFailoverLagLimit configuration property is set to zero) or change tracking enabled, broker enables block change tracking on the new The command fails if the file does not exist. this script is run before the fast-start failover is initiated. 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. If a single-instance primary database (either Oracle RAC or non-Oracle RAC), or if all instances of an Oracle RAC primary database fail, the observer attempts a fast-start failover. file also declares broker configurations and defines configuration Use the Cloud Control Fast-Start Failover wizard or the DGMGRL ENABLE FAST_START FAILOVER command to enable fast-start failover. Verify dmon process is running and broker parameters viz. If you intend to switch back to the original primary database relatively soon, you may allow the physical and snapshot standbys to remain disabled. ), The RedoRoutes property on a far sync instance if it is being used to receive redo from the primary database and ship redo to the target standby database, The standby database that is the target of fast-start failover, A far sync instance if it is being used to receive redo from the primary database and ship redo to the target standby database, Unless the conditions listed in Performing Manual Role Changes When Fast-Start Failover Is Enabled have been met, To a standby database that is not configured as the fast-start failover target. It provides a way to quickly restore a database to a previous point in time or SCN using on-disk data structures called flashback logs. Immediate Failovers in Configurations Using Far Sync Instances. This directory is created when you run the A switchover is a role reversal between the primary database and one of its standby databases. Unless action is taken to change the failover target to one of the bystanders, the new primary will be without a failover target until the former primary is reinstated as a standby. To install Oracle Data Guard, you need to create two Azure VMs on the same availability set: The primary VM (myVM1) has a running Oracle instance. 2. standby database is mounted, broker remembers this setting. When performing a failover in a configuration whose standbys are all of the same type, choose the standby database that has the smallest transport lag. exit. If only a file name is connectivity with target standby. During an immediate failover, the broker performs the failover steps described in How the Broker Performs an Immediate Failover Operation. The following is a sample observer configuration file: Since the broker configuration SALES consists of three databases, Boston, Chicago, and Dallas, with a CONNECT_ID of SALES_P, the SALES_P connect identifier must be defined such that it can reach any instance of any database within the configuration. files include the observer configuration file (observer.ora), observer log Problems with automatic reinstatement are frequently due to misconfiguration, so let's look at this in a bit more detail. Stops Redo Apply or SQL Apply on the standby database immediately, without waiting until all available redo data has been applied. Verify Before Switch-over: configuration property. 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. 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 observer does not attempt to reinstate the former primary database. In this mode, the FastStartFailoverLagLimit configuration property is set to zero. about starting the observer as a background ObserverConnectIdentifier allows you to specify different connect identifiers for the observer to use. Stopping the Observer When There is Only One Observer. In addition, a logical standby database may contain only a subset of the data present in the primary database. . A broker configuration can belong to multiple groups. Step-by-step instructions for manual reinstatement are described in Reenabling Disabled Databases After a Role Change. 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. Complete Failovers in Configurations Using Cascaded Standbys. Switch-over steps: Step-A: Shutdown primary database: SQL> shut immediate; Database closed. This is a good time to enable FSFO to make sure that all of the prerequisites have been met. The real test of the configuration is a successful role transition in both directions with both switchover and FSFO failover. Determines whether or not any standby databases that did not participate in the failover operation have applied redo data beyond the new primary database, and thus need to be disabled. 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; 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. Use Broker's "show configuration" command to determine FSFO status and the "show database statusreport" command to drill down for details if Broker reports a problem. 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. Manual failover can be performed even if the pre-condition checks are not met. Transitions the target standby database into the primary database role, as follows: Changes the role of the database from standby to primary. The following paragraphs describe the supported availability modes. If the observer is unable to regain a connection to the primary database within the specified time, then the observer begins a fast-start failover provided the standby database is ready to fail over. These are the actions the broker performs after you start a complete failover. you need to make the primary database available, first confirm that a 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. primary, only the observers specified in the property can be use in the SET See Disabling Fast-Start Failover. What is true about data guard set up with fast-start failover (FSFO) in Oracle Cloud Infrastructure (OCI)? Connect to the target standby database and issue the FAILOVER command to perform a failover, specifying the name of the standby database that you want to become the primary database: Specify the optional IMMEDIATE clause to perform an immediate failover if any of the following conditions are true: An ORA-752 error has occurred at the standby database, An ORA-600 [3020] error has occurred at the standby database and Oracle support has determined that it was caused by a lost write at the primary database. 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. Slightly less critical than making sure you've got a good primary is making sure the failed primary can be automatically reinstated. See Troubleshooting Problems During a Switchover Operation 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. SWITCHOVER command, and the databases are managed by Oracle Errors occurring for any other configuration members will not impede the switchover. If the group name is not provided, then a new observer is started for each broker configuration defined in observer.ora. Then, on the Failover Confirmation page, click Yes to invoke the default Complete failover option. Now it will return PRIMARY. Queries and DML will continue to run - only sessions that commit will block. Setting it to 'FALSE' leaves the database open and stalled until it is terminated or signaled to proceed in the event a failover did not take place (e.g. If there is only one registered observer, then it works in the same manner that a single observer worked prior to the advent of multiple observers in Oracle Database 12c Release 2 (12.2.0.1). For reliable startup, the initial connection should always be made to the primary. However, re-enabling Flashback Database will require a bounce since the database must be mounted and not open. Use synonyms for the keyword you typed, for example, try "application" instead of "software.". To see Manual Switch Over Manual SwitchOver in Oracle To see Manual Fail Over Manual Failover in Data Guard With Oracle Data Guard [] PRIM>connect /@PRIM as sysdba fast-start failover to the target standby database if conditions warrant a failover. Attempt to open the primary database, or the following error may be returned: This error may return if the fast-start failover validity check fails or does not complete in under two minutes. An spfile is required to persist these changes. The standby VM (myVM2) has the Oracle software installed only. Make sure the last redo data transmitted from the Primary database was applied on the standby database. A failed ping is a ping to The VALIDATE FAST_START FAILOVER command parses the callout The default group is all the configurations defined in the observer configuration file. When fast-start failover is enabled, the primary and standby randomly choose one of the registered observers to be the master. Oracle recommends configuring Flashback Database on every database so that if failover occurs to a physical standby database, you can more easily reinstate any disabled standby databases. Event notification and database connection failover support is available to database clients connected to local database services when a broker-managed failover occurs. Once an immediate failover is started, the broker: Verifies that the target standby database is enabled. In these sample commands, the ellipse () signifies any other add service options you wish to supply.