5.8.5

Table Of Contents
Option Description
Outlier detection variance limit
Sets an error threshold against the progressive fits that are part of the
algorithm to detect outliers.
Outlier percentage of data allowed
before giving up
Sets the threshold for the percentage of data points marked as outliers.
This is useful when vCenter Operations Manager detects too many outliers
and the data set becomes too small to continue outlier detection. The
calculation for the number of data points is (outlier percentage limit x total
number of data points) rounded up to the next whole number. Outliers that
appear in the Average Virtual Machine Capacity view depend on the VM
Count Capacity compound metric and outliers might exceed the threshold
in this global setting because each outlier indicates at least one outlier in
the dependent metrics.
4 Click OK or Finish to save your settings, or select another option to configure.
5 Click Done to close the Configuration dialog box.
The Trend and Forecast Analysis settings are reconfigured.
Example: Examples of Trend and Forecast Analysis Global Settings
These examples show how some of the settings are used.
Forecast Functions -
Use up to data point
number data points for
trend and forecast
You might set the viewing default time window to six but use more data
points for this setting to calculate the trend.
Outlier percentage of
data allowed before
giving up (outlier
detection)
If you have eight data points and you set the percentage to 10,
vCenter Operations Manager takes the final value of .8 and rounds it up to 1.
Outlier Detection and Smoothing Filters in vCenter Operations Manager
vCenter Operations Manager provides data filtering techniques to address outliers and temporary
fluctuations in data points. Outlier detection and smoothing remove anomalies or sudden changes in
patterns during maintenance or other cycles that might mislead the trend and forecast calculations.
When you apply smoothing, vCenter Operations Manager applies a smoothing function to data points and
calculates the trend using the smooth data set. The value of a data point in a graph is affected by the value of
the preceding data points. vCenter Operations Manager assigns a weight or priority to each data point and
that weight determines the contribution of the data point to a smoothed value.
Activating different combinations of outlier detection and smoothing generates different results.
Table 82. Outlier Detection and Smoothing Results
Data Filter Result
No data filter Shows the original data points and trend.
Outlier detection Shows the original data points, trends, and outliers. In the
views, outliers appear as hollow circles.
VMware vCenter Operations Manager Getting Started Guide
108 VMware, Inc.