Bizarre (negative memory) Baseline Recommendations for Tomcat Application Monitor

jimshank

We've recently increased the workload our Tomcat servers are doing and SAM is complaining that we're exceeding the Memory Heap Free thresholds. I decided to lean on the automatic baseline calculator for the new threshold recommendations and it comes up with the following:

I'm not sure why it would recommend a negative threshold so I just went ahead and adjusted them down manually. Has anyone else run into this?

aLTeReGo

If the historical data is very random, then the standard deviation is very high in comparison to mean value. Without looking through the historical values it's difficult to say for certain how these values were arrived at. I suspect however that the negative value is being reached because of the "Less than or equal to" operator. Because of the wild variance in historical values a standard deviation of "3" would likely go below "0" and into negative values. While this doesn't make sense for percentages, it does make sense for other types or metrics collected by SAM.