ENABLE FAST_START FAILOVER

The ENABLE FAST_START FAILOVER command enables the broker to fail over to a specifically-chosen standby database in the event of loss of the primary database, without requiring any manual steps.

See Enabling Fast-Start Failover for complete information.

Format

ENABLE FAST_START FAILOVER [OBSERVE ONLY];

Command Parameters

OBSERVE ONLY:All observers started before or after this command is issued will run in observe-only mode.

Usage Notes

  • The prerequisites described in Prerequisites for Enabling Fast-Start Failover must be met before you issue this command to enable fast-start failover.

  • Issuing the ENABLE FAST_START FAILOVER command does not trigger a failover, it only allows the observer that is monitoring the configuration to initiate a fast-start failover if conditions warrant a failover.

  • You can enable fast-start failover while connected to any database in the broker configuration.

  • If you do not start the observer after you have enabled fast-start failover, the ORA-16819 warning is displayed for the primary and target standby databases. For example: 

    DGMGRL> SHOW DATABASE 'South_Sales';
Database - South_Sales
 
  Role:            PRIMARY
  Intended State:  TRANSPORT-ON
  Instance(s):
    south_sales1
 
  Database Warning(s):
    ORA-16819: fast-start failover observer not started
 
Database Status:
WARNING

  • To enable fast-start failover for a broker configuration with multiple standby databases, the FastStartFailoverTarget configuration property on the primary database must specify one or more viable target standby databases. Both the primary database and the target standby databases must have:

    • Standby redo logs configured

    • Redo transport must be properly configured at both databases for the configured protection mode

    Oracle also recommends Flashback Database be enabled on both the primary and standby databases to allow for reinstatement of the old primary database after a failover. If it is not enabled, then you will receive a warning when you enable fast-start failover:

    DGMGRL> ENABLE FAST_START FAILOVER; 
Warning: ORA-16827: Flashback Database is disabled

    Task 2 in Enabling Fast-Start Failover, and FastStartFailoverTarget provide more information about the FastStartFailoverTarget configuration property.

  • Once you have enabled fast-start failover, you must comply with the restrictions described in Restrictions When Fast-Start Failover is Enabled.

Command Examples

Example 1: Enabling a Fast-Start Failover

The following example enables fast-start failover. 

DGMGRL> ENABLE FAST_START FAILOVER;
Enabled in Zero Data Loss Mode.

Example 2: Successful Enabling of Fast-Start Failover

The following example shows that fast-start failover was successfully enabled when the configuration is operating in maximum performance mode.

DGMGRL> SHOW FAST_START FAILOVER;

Fast-Start Failover: Enabled in Zero Data Loss Mode

  Protection Mode: MaxAvailability
  Lag Limit: 0 seconds

  Threshold:					180 seconds
  Ping Interval: 3000 milliseconds
  Ping Retry: 0
  Active Target:				South_Sales
  Potential Targets:		"South_Sales"
    South_Sales valid
  Observer:							(none)
  Shutdown Primary:			TRUE
  Auto-reinstate:				TRUE
  Observer Reconnect:		(none)
  Observer Override:		FALSE

Configurable Failover Conditions
  Health Conditions:
    Corrupted Controlfile			YES
    Corrupted Dictionary			YES
    Inaccessible Logfile			NO
    Stuck Archiver						NO
    Datafile Write Errors			YES

  Oracle Error Conditions:
    (none)

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