Most generated diagnostic and monitoring events are based on health transitions. When, for example, the state of a device goes from online to offline, a health transition occurs. It is the transition that generates an event, not the offline state.
Transitions cannot be used in the monitoring of log files, so log events can be very repetitive. You can minimize this problem by attaching thresholds to entries in log files.
Thresholds ensure that a minimum number (up to eight) of log file entries occurs within a certain time period before an event is generated. The diagnostic and monitoring software also includes a database that keeps track of the number of events generated about the same subject in the same 8-hour timeframe. You can use this database to stop the generation of repetitive events. For example, if the port of a switch were toggling between offline and online every few minutes, the event maximums database would ensure that this toggling was reported only once every 8 hours, instead of every 5 minutes.
Events are usually generated as follows:
Note -
Aggregated events, as well as events that require action by service personnel (known as actionable events), are also referred to as alarms.