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Service-Checks

Behaviour in case of failure
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Testing depth of single service-checks are customizable. So e.g. on a server can be checked if „MySQL“ is active as well as the database that is provided by „MySQL“ is writable for a specific user. The results of service-checks give information about the availability of monitored ressources. They can also be used for notifications, e.g. failure of components.

A great help for fault analysis offers the possibility to link different system components and its dependencies in the total topology of IT-infrastructure.

Example: A monitored ressource can only be reached by one specific router. If this router is down, the fault way of IT-infrastructure is shown in Nagios' State-Map. A notification to a relevant contact of the component that is down. Devices or services, that are dependent on the faulty router ressource are marked in the State-Map as „unknown“ and there is no extra notification about its state. Because of the dependencies between the ressources unnecessary notifications are avoided. Also a notification about a failure of redundant performed ressource can be sent although there is no failure of function.

Nagios has an extra Flap-Detaction function. That permits to detect various states. E.g. in a period of time X the test of a ressource passes one time and failed one time, at a specified time these ressource is marked as Flapping. That means, a contact or group of person is notified about this state. After that no more notification is sent. So a high number of alerts is avoided, that else will be sent by the service according to the configuration of check-time.

Principally Nagios can monitor all components, that characteristic parameters can be measured or counted in electronic way: storage usage rate, temperatures, system load or if e.g. at a specific date are persons in a computer center - the possibilities are barely limited.