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. The configuration and database status report that the observer is not running and return one of the following status messages: While the configuration is in the unobserved state, fast-start failover cannot happen. The primary database was shut down without using the ABORT option. An application should use caution when calling the DBMS_DG.INITIATE_FS_FAILOVER function because the observer will initiate failover, if at all possible. If the configuration contains physical, snapshot, and logical standby databases, consider choosing a physical standby database as the target standby database. *PATCH V3 0/6] ASoC: codecs: Add Awinic AW883XX audio amplifier driver [not found] <000701d8e7521f78bc05e6a340awinic.com> @ 2022-11-11 11:26 ` wangweidong.a 2022-11 . These facilities allow applications written to take advantage of them to receive asynchronous notification of database events, including role transitions. The broker reinstates a failed primary database as a standby database of the same type (physical or logical standby database) as the old standby database. In these sample commands, the ellipse () signifies any other add service options you wish to supply. FastStartFailoverLagLimit property. Any apply delay must be removed before beginning a switchover. After FSFO is enabled, Broker will continue to check that Flashback Database is enabled during health checks. If you initiated a complete failover and it fails, you might need to use immediate failover. Once the observer is started, you cannot change the file's name and location. A complete failover also attempts to avoid disabling any standby databases that were not the target of the failover, so that they may continue serving as standby databases to the new primary database. Stores the observer runtime data file and observer configuration file in Create a trigger based on the, Oracle Database PL/SQL Language Reference, Choosing a Target Standby Database for Switchover, Choosing a Target Standby Database for Failover, Scenario 9: Performing a Switchover Operation, Scenario 10: Performing a Manual Failover Operation, Database Service Configuration Requirements, Troubleshooting Problems During a Switchover Operation, How the Broker Performs a Complete Failover Operation, How the Broker Performs an Immediate Failover Operation, Setting the Protection Mode for Your Configuration, Scenario 7: Enabling Fast-Start Failover When a Far Sync Instance Is In Use, Description of "Figure 6-1 Relationship of Primary and Standby Databases and the Observer", Enabling Fast-Start Failover Task 7: Configure Actions Before and After Fast-start Failover (Optional), Directing a Fast-Start Failover From an Application, Fast-start Failover Callout Configuration Files, Oracle Data Guard Command-Line Interface Reference, Description of "Figure 6-2 The Observer in the Fast-Start Failover Environment", Oracle Enterprise Manager Command Line Interface. Written by authors well-known for their talent with RAC, Pro Oracle Database 11g RAC on Linux . collections and databases Set up replica sets and automatic failover in MongoDB Use sharding to scale horizontally, and learn how . In an Oracle Data Guard configuration, the SRVCTL -startoption and -role are updated after switchover to reflect the current open mode and database role on the new primary and standby databases. Reinstate the former primary database as a new standby database. You can start the observer before or after you enable The reinstated database acts as the fast-start failover target for the new primary database, making a subsequent fast-start failover possible. If failover occurs to a logical standby database, all physical and snapshot standby databases will be disabled by the broker. To avoid the overhead of recording every change to every block, Flashback Database takes a "fuzzy" snapshot every 30 minutes and only records the before-image block upon its first change since the last snapshot. The redo transport mode used to send redo to the target standby database or the database currently in the primary role. Verify the configuration from both hosts. Commands For Managing Observers on Multiple Configurations. You must provide a connect identifier, through which one or more databases in a specific broker configuration can be reached. Any database that was disabled while multiple role changes were performed cannot be reinstated. Any broker configuration name that is referred to must exist in the configuration declaration section. Broker stores it configuration information in a mirrored set of files outside the database. Some properties have changed between those releases. Overview of Switchover and Failover in a Broker Environment. Regardless of the method you choose, the broker coordinates the role transition on all databases in the configuration. 2. Displays if the standby database's redo applied point does not lag 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. When DGMGRL starts, if the DG_ADMIN Otherwise, they must be re-created from a copy of the new primary database. the observer configuration file is observer.ora. Each observer has its own log file. 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. list of the observers that can become the master observer when that You can, however, perform a manual failover to a snapshot standby. fast-start failover. Instead, it allows an observer that is monitoring the configuration to initiate a fast-start failover should database conditions warrant a failover. 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. 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. variable must have read, write, and execute permissions for the directory owner ObserverConnectIdentifier allows you to specify different connect identifiers for the observer to use. Immediate Failovers in Configurations Using Cascaded Standbys. ZERO DATA LOSS: Fast-start failover is enabled with zero data loss. 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. The former primary database is disabled. If these parameters are modified outside of Broker, it raises a warning. Download Ebook Oracle 11g 12c Data Guard With Asm Lab Practice A Complete Hands On Lab Practice To Manage A Data Guard . time specified by maximum configured configuration property. The column value for V$DATABASE.FS_FAILOVER_STATUS will be SYNCHRONIZED in a configuration operating in maximum availability mode, and it will be TARGET UNDER LAG LIMIT in a configuration operating in maximum performance mode when ready to fast-start failover. The new primary database starts transmitting redo data to the new standby database. The "Configuring Authentication" chapter of the Oracle Database Security Guide provides detailed instructions for creating a wallet. The pre-callout script For information about event notification and database connection failover support for global services, see the Oracle Database Global Data Services Concepts and Administration Guide. Although redo transfer is synchronous, Maximum Availability mode allows the primary to remain available if the standby database becomes unavailable for any reason (e.g. SET MASTEROBSERVER TO allows you to manually change the observer configuration file. For example, if a physical standby database was in the APPLY-OFF state, it will remain in the APPLY-OFF state. November 20, 2009. It can be useful to perform such queries because fast-start failovers are fully automated and can occur at any time. Notice that the former primary is now disabled. These are the actions the broker performs after you start a complete failover. For manual failover, the observer is started and communicating with the target standby database. SQL> Select Database_role from v$Database; Hi, I am working in IT industry with having more than 10 year of experience, worked as an Oracle DBA with a Company and handling different databases like Oracle, SQL Server , DB2 etc If there is only one standby database in the configuration, you can skip this step and continue with Task 3. See Manual Failover for information about manual failover. The target standby database has contact with the primary database. Immediately after issuing command in step 2, shut down and restart the former primary instance PRIM: For zero data loss in maximum availability mode, the FastStartFailoverLagLimit property must be set to zero. The act of switching roles should be a well-planned activity. If you do not want to use the default, you can define a specific group. Stopping a Specific Observer When There are Multiple Observers. For example: The default value for the FastStartFailoverThreshold property is 30 seconds and the lowest possible value is 6 seconds. Before a PRIM>SHUTDOWN IMMEDIATE; This page will not allow you to alter the protection mode. The observer does not need to coordinate fast-start failover when fast-start failover is disabled, so the primary and target standby do not nominate a master observer until fast-start failover is enabled. PRIM>connect /@PRIM as sysdba The target standby database is enabled and is in the APPLY-ON state. The It is then started and stopped on the primary database. To issue commands and interact with the These are the actions the broker performs after you start a switchover. configuration property. You must determine which available standby databases should be targets for failover. If you like a connect-time failover to survive across a data guard switchover, you need another way to do it. Note: Many of the Broker database properties correspond to database spfile parameters. If this occurs, run 'stop observer' and try again. Updates the broker configuration file to record the change in roles. If there are multiple observers, then only one of them is the master observer. If the status is SUCCESS, you're ready to start testing role transitions. The master observer uses the value specified by either the DGConnectIdentifier or ObserverConnectIdentifier database properties to connect to the primary and fast-start failover target standby databases. Starting with Oracle Database Release 21c, use the DG_ADMIN You may failover to a snapshot standby database. 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. To override this behavior and allow a fast-start failover to occur if the observer is unable to contact the primary for more than FastStartFailoverThreshold seconds, set the ObserverOverride property to TRUE. You can customize fast-start failover setup for a specific application by using the DBMS_DG PL/SQL package. If the configured data loss guarantee cannot be upheld, If there is more than one registered observer, then this command returns an error; a name is required if there is more than one observer. When this property is set to the default value of 0, it prevents the observer from periodically establishing a new connection with the primary database. FAN events are published using Oracle Notification Services (ONS) for all Oracle integrated database clients in Oracle Database 12c and later. To run an observer as a background process, use the DGMGRL command START OBSERVER IN BACKGROUND. Both Cloud Control and the DGMGRL CLI will do this automatically as part of failover. You can perform a manual failover even if fast-start failover is enabled. The v$database view has has columns specifically for monitoring FSFO status. Log in as a test user and make some changes that won't impact other parts of the system. The master observer waits the number of seconds specified by the FastStartFailoverThreshold configuration property before attempting a fast-start failover when the primary database has crashed or has lost connectivity with the observer, as in the following situations: The primary database loses its connections with both the observer and target standby database. There are many examples, and Ritesh Chhajer offers this example of doing a Data Guard switchover using dgmgrl: 1. If you want the broker to skip this viability check of bystander standby databases during a complete failover, thus decreasing the overall failover time, set the BystandersFollowRoleChange configuration property to NONE. This lets you take advantage of the broker's Regards, Narottam Tagged: dataguard dba rac Welcome! If you want to use one Oracle home to start multiple observers, with each observer monitoring a different fast-start failover configuration, use the FILE qualifier to specify a unique observer configuration file location for each configuration to be monitored. The Oracle Database 10g FSFO observer is limited to using the default username and password defined in the wallet. A switchover guarantees no data loss. See Oracle Enterprise Manager Command Line Interface. change tracking enabled, broker enables block change tracking on the new You must re-create the database manually from a copy of the current primary database and then reenable the database in the broker configuration. Database dismounted. instructions for the DGMGRL command-line interface. 1. enabling fast-start failover. pre-callout configuration script and post-callout configuration script. time, if all the sessions that are connected though the active services The primary database can be opened even if there is no acknowledgement from the observer or target standby. If automatic reinstatement fails, the broker will log errors and the former primary database will remain in the mounted state. 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. present, you must start the observer manually using the following You cannot perform a switchover to a snapshot standby database unless you first convert it back to a physical standby database. With FSFO enabled, Broker expects to find an observer, which we haven't started yet, so if you verify the at this point with 'show configuration', Broker will report a warning (if it doesn't, give it a minute to discover that the observer isn't there). Subsequent changes to the same block during the same snapshot are not recorded. Fast-start failover is enabled, but this standby database is not the target of the fast-start failover. It could optionally also be removed from the primary database if there is no intention to ever run this service on the current primary database. This property specifies the amount of data, in seconds, that the target standby database can lag behind the primary database in terms of redo applied. While this eliminates the processing overhead associated with periodically establishing a new observer connection to the primary database, it also prevents the observer from detecting that it is not possible to create new connections to the primary database. If the service has been configured to start automatically (-policy AUTOMATIC), then the service will automatically start only after a database role change. the observer was killed after the stall began, but before the failover timeout had elapsed). The original primary database can now be configured as a standby. property. 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. Another good test is to simulate network failures that leave the primary up, but isolated from the failover target standby and the observer. alter database recover managed standby database finish; alter database activate standby database; Managed recovery process has been stopped between primary and standby database and standby becomes primary database. To do this, use the SET ObserverConfigFile and SHOW ObserverConfigFile commands. Without the credentials, Broker will complete the role transition, but will leave the databases in need of a manual restart. Cancel MRP process. You must This table describes the optional database properties that you can set. This can be done regardless of whether the failover was done to a physical, logical, or snapshot standby database. Whether or not you need the FORCE option depends mostly on if the primary and target standby database have network connectivity: If the primary and target standby database have network connectivity, and the database to which you are connected has network connectivity with the primary database, the FORCE option has no effect. On the new primary database STAN, perform a SWITCH LOGFILE to start sending redo data to the standby database PRIM. guaranteed to lose no data. By default, the broker always determines whether bystander standby databases will be viable standby databases for the new primary when performing a complete failover. 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. (as it might in maximum availability and maximum performance modes). database is in the primary role. The configuration must be operating in either maximum availability mode or maximum performance mode in order to be able to switch over to a logical standby database. Issue the following commands on Primary database and Standby database to find out: A switchover guarantees no data loss and is typically done for planned maintenance of the primary system. Automatic failover is optional and can be enabled or disabled on your Autonomous Container Databases with Autonomous Data Guard. This will signal the observer to initiate failover after the FSFO threshold timeout has been reached (default is 30 seconds). To start an observer, you must be able to log in to DGMGRL with an account that has In Oracle Database 11g, the password file on the standby must be a physical copy of the password file on the primary due to security enhancements introduced in Oracle Database 11g. Apply services on all other bystander standby databases automatically begin applying redo data received from the new primary database. databases (PDBs) on any of the instances. To allow the master observer to automatically reinstate the former primary database, the database must be started and mounted. OBSERVE-ONLY: Fast-start failover is enabled in observe-only mode. 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. Manual failover gives you control over exactly when a failover occurs and to which target standby database. alter system set standby_file_management=auto; This parameter must be set before the primary can be opened in Maximum Availability mode. broker configuration, you must connect through another DGMGRL client North_Sales is in the primary role. this directory are used to store the files related to the Provides an automatic failover environment 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. Sign in to Azure The following example displays the contents of the fast-start failover CONNECT command. Starting the Observer Using Cloud Control. Failovers become routine. 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. Services that must be active in any given database role (primary, physical standby, logical standby, or snapshot standby) must be configured with the Server Control utility (SRVCTL) explicitly on each database where the service must be active. To determine if the configuration is ready for fast-start failover to occur, issue the DGMGRL SHOW DATABASE
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