Having played with rule periods over the last few months I tried to see if I could do something interesting with those. My first attempt was to use a history period and to get the min and max/current of this and calculate rate. While this seemed to work at first I quickly realized this would only work if all of this was ever increasing. I then thought that I could use the first value of a history period and the current value and use that for my rate. Unfortunately the first function only works with Xpaths and not history periods. Had a quick chat with Engineering and we came up with the following.
Use two history periods and get the average of each corresponding history period. This should create a reasonable approximation of the growth as long as it is the data-set is reasonably linear.
The formula is then:
rate = ( avg(X) - avg(2X) ) / (X/2)
It looks something like:
set $(first) average(value for "Rolling10Minute")
Example of semi-linear data and rate function using Microsoft Excel compared to Geneos Rate.
Note: History periods requires that gateways retain these points in memory so I would recommend not going overboard with this. Smaller history periods have less data.