The Anomalies graph provides a visual comparison between the actual number of metrics that have abnormal values and the calculated allowable number of metrics with abnormal values.
The Abnormal Metric Count
Any object in vCenter Operations Manager can have hundreds or thousands of collected metrics associated with it. At any time, a subset of these metrics can be abnormal or different from the estimated normal values for the metrics. The current number of metrics that have abnormal values is presented with a blue dot on the right of the Anomalies graph. A blue line represents the number of abnormal metrics for the last 6 hours.
The Noise Line
vCenter Operations Manager uses one of its algorithms to determine how many metrics on an object are usually acting abnormally and create a noise line for the object. The noise line helps to remove the miscellaneous abnormalities, or day to day noise, for an object. Therefore, the more dynamic an object is, the higher its noise level.
In the Anomalies graph, the noise line is presented with a gray line.
If the blue line of the abnormal metric count is far below the noise line, the level of anomalies is normal. If the blue line of abnormal metric count approaches or surpasses the noise line, the object might be experiencing health degradation.