A metric is a unit of measurement used to determine the health of a target. It is through the use of metrics and associated thresholds that Enterprise Manager sends out alerts notifying you of problems with the target.
Thresholds are boundary values against which monitored metric values are compared. For example, for each disk device associated with the Disk Utilization (%) metric, you can define a different warning and critical threshold. Some of the thresholds are predefined by Oracle; others are not.
After a threshold is reached, an alert is generated. An alert is an indicator signifying that a particular condition has been encountered and is triggered when one of the following conditions is true:
A threshold is reached.
An alert has been cleared.
The availability of a monitored service changes. For example, the availability of an application server changes from up to down.
A specific condition occurs. For example, an alert is triggered whenever an error message is written to a database alert log file.
Alerts are detected through a polling-based mechanism by checking for the monitored condition from a separate process at regular, predefined intervals.
See Also:
See the Enterprise Manager Cloud Control Administrator's Guide for additional information about metrics, thresholds, and alerts
Out of the box, Enterprise Manager comes with thresholds for critical metrics. Warning and critical thresholds are used to generate an alert, letting you know of impending problems so that you can address them in a timely manner.
To better suit the monitoring needs of your organization, you can edit the thresholds provided by Enterprise Manager and define new thresholds. When defining thresholds, the key is to choose acceptable values to avoid unnecessary alerts, while still being notified of issues in a timely manner.
You can establish thresholds that will provide pertinent information in a timely manner by defining metric baselines that reflect how your system runs for a normal period of time.
The metrics listed on the Edit Thresholds page are either default metrics provided by Oracle or metrics whose thresholds you can change.
To access metrics in the Cloud Control Console, use the All Metrics page associated with a particular target by doing the following:
From the Cloud Control Console, choose the target.
On the target's home page, click All Metrics in the Related Links section.