The Top-N widget is used extensively in vRealize Operations 6. The default dashboards use them. For example, the Host Overview dashboard use it, as shown below:
Notice in the above screenshot (click if not clear) that there is a little text 24h. That means 24 hours. You can adjust, albeit manually, the time period. The value you are seeing in the above Top-N is the average of an entire 24 hour period. So if there is a peak during the period, it may get flatten. It is also the last 24 hours, not yesterday or today. Checking at 9 am or 6 pm will give you a different result. If you check them at 9 am, you’re looking at 9 am yesterday until 9 am today. You are not looking at yesterday (0000 – 2400).
Because the Top-N is an average, you may want to know a bit more details. This is where the Sparkline widget comes in. Clicking on any of the Top-N will show the corresponding object in the Sparkline widget.
You can certainly change the value from last 24 hours to any time period that fits your business needs. Changing the default dashboards do not impact the way vRealize Operations works (e.g. its dynamic threashold calculation). Dashboards are just way to present information.
You can also create your own dashboard and do your own style. For example, I do not use Sparkline as I like to have greater detail. I use Line Chart. I also use Line Chart first, then Top-N second. So it’s the other way around. This is because I have a preference to see details. I use Top-N when I need to zoom into a specific time line, to reveal the objects giving me the value in the Line Chart. I use this Line Chart + Top-N combo a lot when working with customers. You will find many examples in my book.
If you are curious if the Top-N value is really average of the selected time period, you can easily test it. I created a manual group. It has only 2 members. They are the 2 VMs shown below.
There are 2 Line Chart widgets in the above screenshot. Each of them has a corresponding Top-N widget below it. The first line chart shows a longer time horizon. I chose 7 days. From here I could see that there are some spikes. The Top-N, however, does not reveal that. This is because it is an average. It has flatten the data.
The second line chart shows a much shorter time. I have zoomed into 29 Dec around 1 pm. The line chart shows that BCDR-Prod-SRM-Server had a spike around 50% and then dropped to 4%.
Since the first value is 50.17%, and the second value is 4%, we would expect to see a Top-N showing 27.085%. And you got it right, the Top-N shows 27.085%.