When tracking a counter, it's value is typically reset to 0 when the device is restarted. When aggregating these values in Newts, a counter wrap is detected, leading to extremely large values (in the petabytes range), which can cause spikes in graphs. This distorts the graphs, and makes it difficult to see the other values.
The help remedy this problem with other persistence strategies, we have created tools like the https://wiki.opennms.org/wiki/JRobin_Spike_Hunter.
Since, Newts performs late aggregation, we could look at enhancing the "counter wrap" logic to help prevent these spikes.