Disabling fast-start failover prevents the observer from initiating a failover to the target standby database. In this case, manual failover may still be possible. See
Section 5.4 for information about manual failover.
TARGET UNDER LAG LIMIT
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.
Is possible
SUSPENDED Displays only on the target standby database when either the primary or target standby database was shut down in a controlled fashion (using the NORMAL, IMMEDIATE, or
TRANSACTIONAL, options, but not the ABORT option). Fast-start failover is inhibited in this case. SUSPENDED is cleared when connectivity with the primary database is restored.
Is not possible
SYNCHRONIZED Displays when the primary and target standby databases are synchronized and the
configuration is operating in maximum availability mode.
Is possible if the target standby database displays SYNCHRONIZED and the FS_ FAILOVER_OBSERVER_ PRESENT column displays YES
UNSYNCHRONIZED Displays when the target standby database does not have all of the primary database redo data and the configuration is operating in maximum availability mode.
Is not possible
Note: Disabling fast-start failover does not stop the observer. To stop the observer, see Section 5.5.7.4, "Stopping the Observer".
Table 5–2 (Cont.) FS_FAILOVER_STATUS Column of the V$DATABASE View
Fast-Start Failover
To disable fast-start failover, use the Fast-Start Failover wizard in Enterprise Manager or the DGMGRL DISABLE FAST_START FAILOVER [FORCE] command. The FORCE option disables fast-start failover on the database to which you are connected even when errors occur. 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. Simply use DISABLE FAST_START FAILOVER. This method will disable fast-start failover on all databases in the broker configuration.
If errors occur during the disable operation, the broker returns an error message and stops the disable operation.
■ 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.
The broker may not be able to disable fast-start failover on all databases in the broker configuration when you issue the DISABLE FAST_START FAILOVER FORCE command. As a result, there is no guarantee that the observer will not perform a fast-start failover to the target standby database if the observer determines that conditions warrant a failover. The following list indicates the extent to which fast-start failover is disabled in the broker configuration when the DISABLE FAST_START FAILOVER FORCE command is issued on the primary database, target standby database, and a standby database that is not the fast-start failover target.
If you issue this command on:
– The target standby database when it does not have connectivity with the primary database, fast-start failover is disabled only on the target standby database. In this case, the observer cannot perform a fast-start failover even if conditions warrant a failover. Disabling fast-start failover with the FORCE option when connected to the target standby database guarantees that fast-start failover will not occur.
When the primary database and the target standby database regain network connectivity, the broker will disable fast-start failover for the entire broker configuration.
– The primary database, the primary database attempts to disable fast-start failover on as many databases in the configuration with which it has a network connection. If the primary database does not have connectivity with the target standby database, fast-start failover remains enabled on the target standby database and the observer may still attempt a fast-start failover if conditions warrant a failover.
– Another standby database that does not have connectivity with the primary database, fast-start failover is disabled for this database. Because fast-start failover was not disabled on the target standby database, the observer may
Caution: This action may result in two databases in the
configuration simultaneously assuming the primary database role should fast-start failover occur. For this reason, you should first issue this command on the target standby database.
Fast-Start Failover
still attempt a fast-start failover to the target standby database should conditions warrant a failover.
When the primary database and the (non-target) standby database regain network connectivity, the broker will propagate its current fast-start failover setting (ENABLED or DISABLED) to the non-target standby.
Conditions Requiring the FORCE Option
Disabling fast-start failover without the FORCE option can succeed only if the database on which the command is issued has a network connection with the primary database and if the primary database and target standby database have a network connection. This is the recommended method for disabling fast-start failover.
However, there may be situations in which you must disable fast-start failover when the primary database and the target standby database do not have a network connection, or the database on which you issued the disable fast-start failover
command does not have a network connection to the primary database. In cases where there is a lost network connection, be aware that the observer may attempt a fast-start failover to the target standby database if conditions warrant a failover.
The FORCE option may be the preferred method for disabling fast-start failover when: ■ A network outage isolates the primary database from the observer and the target
standby database, while the databases are ready to failover.
In this case, the primary database stalls and prevents any further transactions from committing because a fast-start failover may have occurred while it was isolated. If you expect the network to be disconnected for a long time and you need to make the primary database available, first confirm that a fast-start failover has not occurred to the target standby database. Then, disable fast-start failover with the FORCE option on the primary database.
If possible, confirm that fast-start failover has not occurred to the target standby database prior to disabling fast-start failover with the FORCE option on the primary database.
■ You want to conduct a manual failover to any standby database in the
configuration (for example, because a failure occurred on the primary database at a time when the primary and target standby database were not ready to failover).
Caution: When you are experiencing network disconnections and you issue the DISABLE FAST_START FAILOVER FORCE command on the primary database or a standby database that does not have connectivity with the primary database, fast-start failover may not be disabled for all databases in the broker configuration. As a result the observer may still initiate fast-start failover to the target standby database, if conditions warrant a failover. This may result in two databases in the configuration simultaneously assuming the primary database role.
Caution: This action may result in two databases in the
configuration simultaneously assuming the primary database role. This can be avoided by first disabling fast-start failover with the FORCE option on the target standby.
Fast-Start Failover
In this case fast-start failover cannot occur because the databases are not ready to failover. You cannot perform a manual failover to the target standby database for the same reason. To proceed, you must first disable fast-start failover using the FORCE option, and then perform a manual failover.
■ A fast-start failover to the target standby database fails.
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. If there is another standby database that is available for failover, you can perform a manual failover to that standby database after you first disable fast-start failover using the FORCE option on that standby database.
■ You want to prevent fast-start failover from occurring because the primary database will resume service soon.
In this case, disable fast-start failover using the FORCE option on the target standby database. Once the primary database regains connectivity with the target standby database, fast-start failover will be disabled for all the databases in the configuration.
Disabling Fast-Start Failover Using Enterprise Manager
Click Disable in the Fast-Start Failover wizard. Then, click Continue to proceed to the next page. See the Enterprise Manager online Help system for more information.
Disabling Fast-Start Failover Using DGMGRL
Issue the DISABLE FAST_START FAILOVER command or the DISABLE FAST_ START FAILOVER FORCE command. See the "DISABLE FAST_START FAILOVER"
command in Chapter 8 for more information.