data guard failover stepsdata guard failover steps

data guard failover steps11 Mar data guard failover steps

status before the crash. Valid values are >= 10. To issue commands and interact with the In previous releases, OCI and ODP.NET clients receive FAN notifications via Oracle Advanced Queuing (AQ). Group definition this section is optional. Verify Before Switch-over: Note that if failover was performed on a snapshot standby database, the old primary must be either reinstated or re-created as a physical standby database. The observer is the key element that separates Data Guard failover from its pre-FSFO role as the plan of last resort to its leading role in a robust high availability solution. If this occurs, run 'stop observer' and try again. This example shows the verbose mode of the 'show configuration' command that provides FSFO-specific information. Errors occurring for any other configuration members will not impede the switchover. the primary database that failed or took longer than the time created under this directory by DGMGRL will also have the same permissions. There can be up to four November 20, 2009. This can be avoided by first disabling fast-start failover with the FORCE option on the target standby. Transitions the target standby database into the primary role, opens the new primary database in read/write mode, and starts redo transport services. databases (PDBs) on any of the instances. ORACLE instance shut down. The foundation of FSFO is Data Guard - a primary and at least one standby. The state file is locked when the observer is running to prevent multiple observers from using the same file. A normal shutdown uses SHUTDOWN NORMAL, SHUTDOWN IMMEDIATE, or SHUTDOWN TRANSACTIONAL. However, the event notifying a failover is only published for database services that have been configured to be active while the database is in the primary role on the new primary database. observers are registered, a directory named To specify which observer can be a master observer when a database is in As a result the observer may still initiate fast-start failover to the target standby database, if conditions warrant a failover. not already enabled, the observer waits until fast-start failover On the new primary database STAN, perform a SWITCH LOGFILE to start sending redo data to the standby database PRIM. See Oracle Enterprise Manager Command Line Interface. In fact, failovers are so reliable, fast, and simple that switchovers become the exception rather than the rule. This can be avoided by first disabling fast-start failover with the FORCE option on the target standby. When a primary loses contact with both the failover target and the observer simultaneously, it enters a "stalled" state (v$database.fs_failover_status = 'STALLED') and any sessions still connected to the primary will block on commit. More specifically, we can have an asynchronous second read-only Managed instance in the same or in a different region. time specified in the WAIT option. The minimum value of ObserverPingInterval is 100 If automatic reinstatement fails, the broker will log errors and the former primary database will remain in the mounted state. Using the db_unique_name of each database as the Oracle Net alias is simple and intuitive. RAM). The failover time is dependent upon whether the target standby database (physical or logical standby database) has applied all of the redo data it has received from the primary database. To verify this change, again query the Database_role column of V$DATABASE. The new primary database starts transmitting redo data to the new standby database. If you do not want to use the default, you can define a specific group. In short, the failover is the deformation of the production (primary) database and activating standby database as the primary. ob2-host can be a master observer when 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. Note that enabling FSFO does not make the configuration ready for automatic failover - that requires an observer, which we'll get to next. STOP OBSERVING, and SET multiple, inexpensive servers is the basis for the failover and other fault-tolerance features that RAC provides. 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/. The commands that can be executed for a group of configurations (as declared in an observer configuration file) are as follows. Set both these properties to achieve a primary failure detection time of 1 In this example, there are 3 ORLs with a max group# of 3. Once Flashback Database has succeeded, the observer will convert the database to a standby, bounce it, and begin apply services. first recording that a fast-start failover cannot happen. The Column Value in the following table is consistent across instances in an Oracle Real Applications Clusters (Oracle RAC) environment. 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. See FastStartFailoverTarget for more information about this property. 3. The FastStartFailoverThreshold time interval starts when the observer first detects there might be a failure with the primary database. to set the time taken to detect a failure on the primary database: Set the FastStartFailoverThreshold The same process should work for RAC environment as my colleague has . The platform provides comprehensive services such as maintaining and monitoring databases to help the oracle databases in surviving during data corruption. In the restore stage, Flashback Database restores the database to a point prior to the standby_became_primary_scn using the before-image blocks in the Flashback Database logs. However, fast-start failover cannot occur when the target standby database is in an unobserved state. You have done a failover to your Standby database so it becomes the new Primary. Disabling fast-start failover does not stop the observer. When both databases have been restarted, you may restart the observer. 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 What is true about Data Guard setup with fast-start failover? 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. configuration file exists. Data Guard Switchover/failover to standby The standby database will be activated to serve as the primary database at some point in its life cycle. STANDBY> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY; Issue the following command while connected to any database in the broker configuration, except the database that is to be reinstated: The newly reinstated standby database will begin serving as a standby database to the new primary database. These are some points to consider before you begin a switchover. FastStartFailoverAutoReinstate is set to FALSE, Another failover or switchover occurred after the fast-start failover completed but before the former primary database restarted, The master observer cannot connect to the former primary database, The former primary database cannot connect to the new primary database, The former primary database and the new primary database are not configured in the same fast-start failover environment, The former primary database was disabled because of a manual failover when fast-start failover was disabled. callout directory. This database property is used to specify how the observer should connect to and monitor the primary and standby database. Check the database role,open_mode in standby server. It automatically sets Data Guard related database initialization parameters on instance start and role transitions, starts apply services for standbys, and automates many of the administrative tasks associated with maintaining a Data Guard configuration. The syntax for the optional definition of a broker configuration group is: The group definition section is optional. 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. Unlike ORLs, SRLs should be created with only one member per group. Es gratis registrarse y presentar tus propuestas laborales. 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. Data Guard Broker - Controls the creation and monitoring of Data Guard. The log file name is specified with the LOGFILE IS option of the START OBSERVER command. The observer is perfectly satisfied if all of the redo it needs to meet your durability requirements has been received by the failover target. milliseconds. On Linux/Unix, the directory specified by the DG_ADMIN environment This brings up the General Properties page that provides a Reinstate button. To verify the observer is started and the configuration is ready for The broker preserves the protection mode that was in effect prior to the failover. During a switchover, the primary database transitions to a standby role, and the standby database transitions to the primary role. Use the SQL ALTER DATABASE MOVE DATAFILE command to rename or relocate an online data file on a physical standby that is a fast-start failover target if the standby is mounted, but not open. environment that is guaranteed to either lose no data (when the Waits for the target standby database to finish applying any unapplied redo data before stopping Redo Apply (if the target is a physical standby database) or SQL Apply (if the target is a logical standby database). To enable fast-start failover, both the primary and target standby databases must be running and have connectivity, and satisfy all of the prerequisite conditions listed in Prerequisites for Enabling Fast-Start Failover. 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. For example: Scenario 6: Enabling Fast-Start Failover and Starting the Observer. The default group is all the configurations defined in the observer configuration file. The new primary database is opened in read/write mode and redo transport services are started. The foundation of FSFO is Data Guard - a primary and at least one standby. Otherwise, the DUPLICATE TARGET DATABASE command will fail with "RMAN-20208: UNTIL CHANGE is before RESETLOGS change". The FS_FAILOVER_STATUS column in the V$DATABASE view for the target standby database displays a reason why fast-start failover cannot occur. For any work, queries and help. 3. Oracle Database 11g observers are incompatible with 10g databases and vice-versa. file, observer runtime data file (fsfo.dat), fast-start failover callout Else, broker restarts the new These FAN events can be used in the following ways: Applications can use FAN without programmatic changes if they use one of these Oracle integrated database clients: Oracle Database JDBC, Oracle Database Oracle Call Interface (OCI), Oracle Data Provider for .NET ( ODP.NET), or Universal Connection Pool for Java. database is in the primary role. Step 4: Enable Fast-Start Failover Now we are ready to enable FSFO: DGMGRL> enable fast_start failover; Enabled in Zero Data Loss Mode. The standby database must be re-created or reinstated before it can serve as a standby for the new primary database. standby database is mounted, broker remembers this setting. orapwd file=$ORACLE_HOME/dbs/orapw$ORACLE_SID. If you will be using RMAN to create the standby database, it also needs a static service to restart the database being created. This is normal. By default the file is named fsfo.dat and is created in the working directory where the observer is started. This document only talks about switchover involving physical standby database. Prerequisites for Enabling Fast-Start Failover provides complete information about all of the fast-start failover and reinstatement requirements. Specifying Preferred Observers Based on Current Primary. You can use Cloud Control or DGMGRL, to perform either a complete (recommended) or an immediate failover. Table 6-1 Content of Default Directory for Client-side Files, Contains the observer configuration file that is used by 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. In this example, the original primary data is called PRIM and the original standby database is called STAN. Use the Cloud Control Fast-Start Failover wizard or the DGMGRL ENABLE FAST_START FAILOVER command to enable fast-start failover. Multiplexing SRLs merely adds unnecessary IO and can increase commit latency. Databases that can be reinstated will have the following status value: For the REINSTATE command to succeed, Flashback Database must have Now it will return PRIMARY. ObserverConfigFile is a DGMGRL session runtime property. To use a far sync instance with fast-start failover, the far sync instance transport mode must be set to either SYNC or FASTSYNC and the target standby database transport mode must be set to ASYNC. Add an entry to the oratab file for the standby, db1:/u01/app/oracle/product/11.1.0/db_1:Y. If no value is specified for the When running the START If this It has two parts in the following order: Configuration declaration this section is mandatory. switch does not happen until the next time the primary contacts the target standby, A far sync instance or Zero Data Loss Recovery Appliance is not a database and therefore cannot be the target of a role transition. The word manual is used to contrast this type of failover with a fast-start failover (described in Fast-Start Failover). (For example, if the DBMS_LOGSTDBY.SKIP procedure was used to specify which database operations done on the primary database will not be applied to the logical standby database.). Nothing will ruin your day faster than finding out that the standby the observer just failed over to is 12 hours behind in applying redo. We will create 4 SRLs starting with group# 11. FAN events are always published through ONS. If the primary database has multiple standby databases, then you can specify multiple fast-start failover targets, using the FastStartFailoverTarget property. Start the Data Guard listener on both "a" and "b" hosts. files to automate tasks that must be performed before and after a fast-start failover 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. Steps for FAILOVER the Dataguard environment 1. What is true about data guard set up with fast-start failover (FSFO) in Oracle Cloud Infrastructure (OCI)? With increased latency comes decreased throughput; however, in some cases the difference in throughput may be made up by increasing parallelism. Event notification and database connection failover support is available to database clients connected to local database services when a broker-managed failover occurs. The ObserverOverride and ObserverReconnect properties allow you additional control over the connection to the primary. Flashing back a database is much faster and more seamless (one simple DDL statement) than traditional point-in-time or SCN-based recovery. The remaining Data Guard-related parameters will be set by Broker later in the walkthrough. LGWR is unable to write to any member of the log group because on an I/O error. You can create two callout configuration scripts, a To see Manual Switch Over Manual SwitchOver in Oracle To see Manual Fail Over Manual Failover in Data Guard With Oracle Data Guard [] the observer was killed after the stall began, but before the failover timeout had elapsed). If you expect the network to be disconnected for a long time and In Oracle RAC configurations, the Inaccessible Logfile and Stuck Archiver health conditions may only be applicable to a single instance. (If there are other conditions, unique to an application, that would warrant a fast-start failover then the application can be set up to call the DBMS_DG.INITIATE_FS_FAILOVER function and start a fast-start failover immediately should any of those conditions occur. This is typically done for planned maintenance of the primary system. To reenable broker management of these databases, you must reinstate or re-create the databases using one of the following procedures: If a database can be reinstated, the database will show the following status: Reinstate the database using the DGMGRL REINSTATE DATABASE command or the reinstate option in Cloud Control, as described in How to Reinstate a Database. The broker allows a complete failover to proceed as long as there are no errors present on the standby database that you selected to participate in the failover. Figure 6-2 The Observer in the Fast-Start Failover Environment. When DGMGRL starts, if the DG_ADMIN become the master observer. Oracle Data Guard Broker is a utility that can help you manage your Oracle Data Guard. Overall commit latency is increased by the round-trip network latency. The old Primary must have been running in flashback mode before the failover. The column value for V$DATABASE.FS_FAILOVER_STATUS will be SYNCHRONIZED in a configuration operating in maximum availability mode, and it will be TARGET UNDER LAG LIMIT in a configuration operating in maximum performance mode when ready to fast-start failover. The observer is the third party in an otherwise typical primary/standby Data Guard configuration. Now let's test switchover in the other direction. This section describes how to configure and verify each prerequisite. For example: In the following example, assume the network between the primary database and the observer has failed. It is then started and stopped on the primary database. Each group that you define must have at least one broker configuration. The new ConfigurationWideServiceName configuration property can be used to simplify setting up this connect identifier. SQL>connect /@STAN as sysdba It is important that all SRVCTL add service options be identical on all the databases so that the services behave the same way before and after a role change. If Flashback Database was enabled on the primary database.If not, the whole setup process must be followed, but this time using the original primary server as the standby. 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 FastStartFailoverLagLimit property. 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. For example: Using DGMGRL, you can do this by examining the output of the SHOW CONFIGURATION LAG. For this reason, you should first issue this command on the target standby database. 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. Database dismounted. If the WAIT option is included in the If failover is not possible for some reason, then the master observer will continue checking whether the standby database is ready to fail over. only. A high lag limit may lead to more data loss but may lessen the performance impact of the primary database. Reset database properties related to Redo Apply services, such as DelayMins. You must specify it every time you start a new DGMGRL client. fast-start failover to the target standby database if conditions warrant a failover. You can use the SHOW CONFIGURATION WHEN PRIMARY IS command to show the redo transport configuration (based on each member's setting of the RedoRoutes property) that would be in effect if the specified database were the primary database. Fast-start failover is faster when you take steps to optimize recovery so that the application of redo data to the standby database is kept up to date with the primary database's rate of redo application. Switches roles between the primary and standby databases. For Active Oracle Data Guard, it will fail to open up a connection unless its in read-only mode. Role Transitions: Switchover and Failover 1 -7 Oracle Data Guard Broker Framework 1 -9 C hoosing an Interface for Administering a Data Guard Configuration 1 -10 Oracle Data Guard: Architecture (Overview) 1 -11 Primary Database Processes 1 -12 . Oracle also provides Fast Application Notification (FAN) for OCI clients and Fast Connect Failover for JDBC clients. Remember to check Flashback Database history before aborting the primary. primary database must have network connectivity. When fast-start failover is enabled, the primary and standby randomly choose one of the registered observers to be the master. Note that the database will not open at this point. The following table summarizes which standby types are supported in which protection modes when fast-start failover is enabled. For the RMAN duplicate active database method, the init.ora file (initdb1.ora in the example) requires only one parameter: db_name (it doesn't even have to be the real name of the database - any name will do).

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