12c ADG 延迟告警，延迟消失后，告警自动消失。

DGMGRL> show configuration;Configuration - dg_config Protection Mode: MaxPerformance Members: orcldg - Primary database orcl - Physical standby database Warning: ORA-16857: standby disconnected from redo source for longer than specified thresholdFast-Start Failover: DISABLEDConfiguration Status:WARNING (status updated 41 seconds ago)DGMGRL> exit<roidb01:orcl:/home/oracle>$oerr ora 1685716857,0000, "standby disconnected from redo source for longer than specified threshold"// *Cause: The amount of time the standby was disconnected from the // redo source database exceeded the value specified by the // 'TransportDisconnectedThreshold' database property. It is caused by // no network connectivity between the redo source and the standby // databases.// *Action: Ensure that there is network connectivity between the redo source// and standby databases, and the redo source is working properly.<roidb01:orcl:/home/oracle>$dgmgrl /DGMGRL for Linux: Version 12.1.0.2.0 - 64bit ProductionCopyright (c) 2000, 2013, Oracle. All rights reserved.Welcome to DGMGRL, type "help" for information.Connected as SYSDG.DGMGRL> show configuration;Configuration - dg_config Protection Mode: MaxPerformance Members: orcldg - Primary database orcl - Physical standby database Fast-Start Failover: DISABLEDConfiguration Status:SUCCESS (status updated 20 seconds ago)DGMGRL> 说明：

The Data Guard broker also has configurable database properties that can be used to generate warnings when a transport or apply lag exceed a user defined value:The ApplyLagThreshold configurable database property generates a warning status for a logical or physical standby when the database's apply lag exceeds the value specified by the property. The property value is expressed in seconds. A value of 0 seconds results in no warnings being generated when an apply lag exists. As a best practice, Oracle recommends setting ApplyLagThreshold to at least 15 minutes.The TransportLagThreshold configurable database property can be used to generate a warning status for a logical, physical, or snapshot standby when the database's transport lag exceeds the value specified by the property. The property value is expressed in seconds. A value of 0 seconds results in no warnings being generated when a transport lag exists. As a best practice, Oracle recommends setting TransportLagThreshold to at least 15 minutes.