Interacting with the EM12c Console - Expert Oracle Enterprise Manager 12c - page 141

If you expand the Capacity category and click on a tablespace used metric, you see the common metric
configuration page, shown in Figure 4-52 , allowing you to set the frequency of collection and upload interval. This
functionality is common to all metrics for all managed targets. A management metric in this case is just a data point of
interest—for example, the amount of free space in an Oracle tablespace. The metrics are collected by the agent at the
configured frequency and uploaded every so many collections (in this case, every time).
Figure 4-52. Tablespaces Full metric details
The available metrics vary by target type, but the configuration of the collection and upload is common across
the product. The prime reason, of course, for collecting metrics is to allow analysis and alerting to take place. In
Enterprise Manager, for historic reasons, alerting has a specific technical meaning that is different from common
English usage. Specifically, an alert occurs when a metric crosses a threshold set by an administrator (this may have to
occur for several collections in a row to avoid false positives). There is no association between an alert occurring and
an administrator being notified.
The Metric and Collection Settings menu offers a different view of the metric collection configuration, grouping
metrics by type, and allowing you to change the schedule for collecting the value of the metric and to define thresholds
for that metric that represent warning or critical states for the collected metric. Figure 4-53 illustrates this interface for
a database target.