I have selected my vCenter Server Appliance; I want to look at the Guest Demand (KB) to understand the amount of resources being used before I right-size my virtual machine. I scroll down the metrics selector, expand Memory, and then double click on Guest Demand (KB). In the panel to the right it shows me a graph for the past 6 hours. I notice the high value is 2,503,718 KB and the low value is 1,796,278 KB.
But, I want to look at a more extensive time slice so I understand the demand over the past 30 days. To do this, I click the calendar icon and drop-down the range selection for the Last 30 days.
This brings up a graph over the past 30 days, as seen below. Now I see that I have a high value of 6,463,421 KB and a low value of 1,377,965 KB.
Now this is the part that I learned accidentally today, but I think it is very cool! If you drag over a specific range in the graph, it will bring up the Guest Demand (KB) details for that period. No need to attempt a haphazard guess at the date and time range for the spike.
This gives me a better perspective on that time frame and when the spike for demand occurred.
Now in a real world scenario, I want to understand exactly when it happened and how long it lasted. Again, I am going to select the spike so I can get a better understanding of the timeline. Now I see that the issue started around 3:30 AM and lasted until around 4:30 AM.
You will recognize that there is a big gap in the dots in the timeline, the dots are my 5 minute intervals, the spike occurred because I was performing maintenance on my lab environment and I was restarting the vCenter Server Appliance.
That is pretty powerful when trying to find the root cause of an issue!
VMware vCenter performance shows 30 minute intervals over the past week and 2-hour intervals over the past month. vRealize Operations shows 5 minute intervals for the past 6 months. A two-hour average can hide a lot of peaks and valleys, it might be beneficial for some general capacity planning, but it isn't good if you are trying to troubleshoot the root cause of an application performance issue or trying to gain insight into the environment when trying to right-size a virtual machines.
