How setting the All Baselines option affects absolute instance thresholds
Sometimes, the value of a threshold shown in a graph is different from the value of the absolute instance threshold that is set.The value of a threshold is calculated as (all baselines + absolute threshold value). When the threshold is set to take baselines into consideration, the highest or lowest value (above or below threshold values, respectively) of the threshold is calculated.
During every poll, all three baseline values (hourly, daily, and weekly) and the absolute threshold value are checked, and the highest or lowest value becomes the threshold at that point.
For example, assume that the absolute instance threshold value of a response time attribute is set to Minor when it is above 200 milliseconds, and the All Baselines option is selected. At one data point, if the value of the response time is 200 milliseconds, hourly baseline is 240 milliseconds, daily baseline is 230 milliseconds, and weekly baseline is 210 milliseconds for that point of time, no alarm is generated because it has not violated the highest threshold of 240 milliseconds.
The All Baselines is calculated based on the following formulas:
- High All Baseline will choose the maximum of the hourly, daily and weekly baselines hour by hour.
- Low All Baseline it will choose minimum of the hourly, daily and weekly baselines hour by hour.