In System Center Essentials 2010, static threshold unit monitors measure a performance counter object relative to a user-defined static value, at specific intervals. When the value of the performance object being measured exceeds the defined threshold, the state of the monitor changes.
You can use the Create a Unit Monitor Wizard to create a static unit threshold monitor. You can open the wizard by clicking Create a monitor in the Actions pane of the Authoring area and then selecting Windows Performance Counter under Select the type of monitor to create.
In Essentials 2010, two types of static thresholds are available:
- Single threshold
- Double threshold
Single Threshold Monitor
A single threshold monitor has one limit. When the performance counter goes either above or below that limit, the state of the monitor changes. The state change can be configured to be success, warning, or error.
An example of what a single threshold monitor does is that it monitors remaining free disk space. For example, suppose you want to monitor free disk space. Using a single threshold monitor, you might set a threshold of 1 GB so that when your free disk space falls below 1 GB, a warning or error state is set.
Essentials supports the following types of threshold unit monitors:
- Simple threshold A
simple threshold monitor measures the value of a performance object
against a fixed limit. If the value of the performance object goes
above or below the fixed limit, the state of the monitor changes.
On one side of the threshold, the state of the monitor is success;
on the other side, the state is either warning or error.
- Average threshold An
average threshold monitor measures the value of a performance
object against a fixed limit. In addition, an average threshold
monitor examines n number of samples and takes the average
value of those samples to determine whether the threshold has been
exceeded. This type of threshold monitor always examines the most
recent n number of samples.
- Consecutive samples over
consecutive-samples-over-threshold monitor is useful when sudden
increases in a performance counter generate false alarms. A
consecutive-samples-over-threshold monitor changes the state of the
monitor only if the performance counter exceeds a threshold for
n number of consecutive samples. With this type of monitor,
you can configure the threshold to be greater than, greater than or
equal to, less than, or less than or equal to a specified
- Delta threshold A
delta threshold monitor measures the rate of change in n
number of samples. The rate of change can be expressed as an
absolute value (for example, a change of 10 GB over the last five
samples) or as a percentage (for example, a change of 5 percent
over the last five samples).
Double Threshold Monitor
A double threshold monitor examines two limits. When a performance counter value crosses the first limit, the state of the monitor changes. If the value continues to climb or decline and crosses the second limit, the state changes a second time.
For example, assume the first threshold is set at 1.5 GB and the second one is set at 1 GB. If the amount of free disk space is above 1.5 GB, the state of the monitor is success (green). If free disk space goes below 1.5 GB, the state of the monitor changes to warning (yellow); if free disk space goes below 1 GB, the state changes to error (red).