Hi Dragutin I understood the concept after realizaing the threshold was calculated as sample percentile. Thanks for the explanation though. What I understand is that adaptive threshold is calculated using samples from previous days, let's say AAS, if the collected data has 100 samples from values 0 to 15 and the 99 percentile value is 14 then that will be used as the critical threshold, if 14 occured twice then a alert will be raised (the occurance 2 is the default value). In OEM 12.1.0.4 it no longer recommends the usual adaptive threshold from the database, OEM now calculates the database threshold itself. I am having a few issues with advanced threshold management and have a few SR open all waiting for internal responses :-/ Thanks! On Tue, Nov 4, 2014 at 8:29 PM, Dragutin Jastrebic <orahawk@xxxxxxxxx> wrote: > => > By reading the above statement it seems t me that it is saying for warning > level it will rise an warning alert when 0.05 percent of observations are > above the threshold and raise a critical alert when it is 0.01 percent. > Should not it be the opposite? When a higher number of observation is > higher than the threshold a critical alert should be raised? > <= > > No, it is not the opposite, this is exactly the way it is supposed to > work, since the Significance Level adaptive treshold is used to capture > seldom, unusal values, > > For exemple, with OEM 12c you have a metric "Average number of active > sessions", with the > following defaults: > > Very high level (0.99) for a warning treshold > Extreme level (0.9999) for a critical treshold. > > The value that has 1 occurence in 100 will trigger a warning alert, but > the value that has 1 occurence in 10000 will trigger a critical alert > > So more unusual the value is, it is estimated as more critical. > > BTW, it seems that OEM 12c with its quick configuration, is mostly > suggesting Significance Level > for OLTP and Percentage of Maximum for DW systems. > This make sense: we are more interested to capture seldom > values in OLTP that in DW database > > Beside Oracle documentation, for more information about the adaptive > tresholds, you have a good explanation on Asktom=> > > > https://asktom.oracle.com/pls/apex/f?p=100:11:0::::P11_QUESTION_ID:1525205200346930663 > > Also, I have written a little article about this topic on my blog, this is > strictly nothing new, but there are 2 pictures that can help the global > understanding of adaptive tresholds > > http://jastrebicdragutin.wordpress.com/2014/11/03/adaptive-tresholds/ > > HTH > Dragutin > >> >> >