Version 9 changed the behavior of some alarm notifications when it introduced the new incident management system.
Now, when an alarm is no longer critical, rather than immediately returning to an OK state (and sending the related notifications), it enters what’s called an “Alarms Cleared” state. This state is a window of time that acts as a buffer to allow the alarm time to stabilize before returning it to an OK state. This prevents redundant and false alarm notifications for alarms that are experiencing a flapping condition. If the alarm fails to stabilize, it will then be returned to whatever state the opened incident was last in (typically, open or acknowledged) without any further action.
The default delay time for the Alarms Cleared window is 5 minutes, but in version 9.1 and newer the delay can be customized by an administrator.
Note: If you lower the delay timer and you have flapping devices, this change could increase the volume of notifications that you receive (directly proportional to the number of flapping devices).
To change the delay timer: From the main menu, select Administration > Alerts > Incident Management. Set the Incident Close Delay Timer field to the desired number of minutes and click Update.