Statuses show the availability of a host, and the availability or performance of a service. Each status has a precise meaning for the resource. Each status is determined following the monitoring of the resource according to user-defined thresholds.
The table below summarizes all the possible statuses for a host.
|UP||The host is available and reachable|
|DOWN||The host is unavailable|
|UNREACHABLE||The host is unreachable: it depends on a host whose status is DOWN|
The table below summarizes all the possible statuses for a service.
|OK||The service presents no problem|
|WARNING||The service has reached the warning threshold|
|CRITICAL||The service has reached the critical threshold|
|UNKNOWN||The status of the service cannot be checked (e.g.: SNMP agent down, etc.)|
In addition to the standard statuses, new statuses can be used to add additional information:
- The PENDING status is a status displayed for a service or a host freshly configured but which has not yet been checked by the scheduler.
- The UNREACHABLE status is a status indicating that the host (parent relationship) is situated downstream of a host with a DOWN status.
- The FLAPPING status is a status indicating that the status change percentage of the resource is very high. This percentage is obtained from calculations performed by the network monitoring engine.
- The ACKNOWLEDGED status is a status indicating that the incident of the service or of the host has been taken into account by a user.
- The DOWNTIME status is a status indicating that the incident of the service or of the host occurred during a downtime period.
A resource can have two states:
- SOFT: Signifies that an incident has just been detected and that it has to be confirmed.
- HARD: Signifies that the status of the incident is confirmed. Once the status is confirmed, the notification process is engaged (sending of a mail, SMS, etc.).
An incident (Not-OK status) is confirmed as soon as the number of validation attempts has reached its end. The configuration of a resource (host or service) requires a regular check interval, a number of attempts to confirm a Not-OK status and an irregular check interval. As soon as the first incident is detected, the state is "SOFT" until its confirmation into "HARD", triggering the notification process.
A service has the following check settings:
- Max check attempts: 3
- Normal check interval: 5 minutes
- Retry check interval: 1 minute
Let us imagine the following scenario:
|Time||Check attempt||Status||State||State change||Note|
|t+0||1/3||OK||HARD||No||Initial state of the service|
|t+5||1/3||CRITICAL||SOFT||Yes||First detection of a non-OK state. Event handlers execute.|
|t+6||2/3||WARNING||SOFT||Yes||Service continues to be in a non-OK state. Event handlers execute.|
|t+7||3/3||CRITICAL||HARD||Yes||Max check attempts has been reached, so service goes into a HARD state. Event handlers execute and a problem notification is sent out. Check # is reset to 1 immediately after this happens.|
|t+12||3/3||WARNING||HARD||Yes||Service changes to a HARD WARNING state. Event handlers execute and a problem notification is sent out.|
|t+17||3/3||WARNING||HARD||No||Service stabilizes in a HARD problem state. Depending on what the notification interval for the service is, another notification might be sent out.|
|t+22||1/3||OK||HARD||Yes||Service experiences a HARD recovery. Event handlers execute and a recovery notification is sent out.|
|t+27||1/3||OK||HARD||No||Service is still OK.|
|t+32||1/3||UNKNOWN||SOFT||Yes||Service is detected as changing to a SOFT non-OK state. Event handlers execute.|
|t+33||2/3||OK||SOFT||Yes||Service experiences a SOFT recovery. Event handlers execute, but notification are not sent, as this wasn't a "real" problem. State type is set HARD and check # is reset to 1 immediately after this happens.|
|t+34||1/3||OK||HARD||No||Service stabilizes in an OK state.|