There are several key metrics to understanding the load on your pollers.
Elements - is the total number of NPM related elements being polled by the poller
Network Node Elements - is the total number of 'nodes' being polled by the poller.
Volume Elements - is the total number of 'volumes' being polled by the poller.
Interface Elements - is the total number of 'interfaces' being polled by the poller.
These metrics are the actual elements not the number of metrics being collected. For instance, when polling an interface that you are collecting traffic statistics on, you can be collecting up to 14 metrics (i.e. Total Packets/sec, Total Bits/sec, etc). Also be aware that these element counts do not include SAM components, Hardware health monitors, Asset inventory pollers or WPM transactions.
A 24 port switch would show up as 1 Network Node Element and (depending on the number of Vlans, trunks, or subinterfaces configured) as few as 24 Interface Elements for a total of 25 elements. If you were to remove 12 interfaces it would then count as 1 network node element and 12 interfaces for a total of 13 elements.
Solarwinds claims a per poller element rate of 8,000 total elements at a statistics polling rate of 10 minutes. This element limitation does include SAM component monitors and other module polling being done on the poller, despite the fact that they are not included in the 'Elements' number. If you decrease your statistic polling then your maximum elements that can be polled on a poller decreases (i.e. If your statistic polling interval is lowered to 5 minutes your max elemets per poller is reduced to 4,000 elements.). Subsequently, you can increase your statistic polling interval you can increase the max elements per poller. However, your status polling interval has a lower impact on your poller due to the vastly lower number of metrics that are pulled.
We have pushed our pollers and found that these element/component limits are pretty accurate.
When it comes to poller load the real question is, "Are you seeing gaps in your data?" If you polling rate is high, your polling completion percentage is 99% or better, and your not seeing any gaps in your data, then poll on!
I know there's a good video that goes over the basics of poller load statistics and the 'Polling Engines' admin page. If I can find it again, I'll reply with the link.
