Alarms

Horizon uses a network’s managed entities, their resources, the services they provide, and any applications that they host to monitor problem states.

While events carry immutable problem state attributes such as severity, alarms indicate problems in the network (see Business Service Monitoring) and carry changeable attributes such as acknowledgment.

Single alarm tracking problem states

An alarm is instantiated on the first occurrence of a service-down problem:

Alarm List displaying one alarm of minor severity
Figure 1. service-down alarm created

Click the number displayed in the Count column to display the corresponding events and their details:

Alarm Details page displaying a service down event
Figure 2. Alarm displaying service down event

The alarm is cleared immediately when service is restored, and no alarm is created when the service returns to a normal state:

Alarm List displaying one cleared alarm and its log message
Figure 3. Alarm cleared
Alarm Details page displaying one service down event and one service restored event
Figure 4. Service down and service restored events

If the problem occurs again, the events are reduced into the existing alarm. The alarm’s count is updated to reflect the new activity:

Alarm List displaying one alarm with a count of 2
Figure 5. Reduced alarm
Detailed event list page displaying two service down events and one service restored event, all of which are members of the same alarm
Figure 6. List of events

The alarm is once again cleared immediately when service is restored:

Alarm List displaying one cleared alarm with a count of 2, and its log message
Figure 7. Reduced alarm cleared

Note that the alarm’s count does not increment when the problem is resolved.

Detailed event list page displaying two service down events and two service restored events, all of which are members of the same alarm
Figure 8. Service down and restored events