The first and most important aspect to cover with capacity management in vRealize Operations is all about policies. Policies are the King. The calculations and recommendations for all areas of capacity management are directly related to what policy options are configured and currently active on the selected resource.
It is highly improbable that one policy is suitable for all workload types such as a server, VDI, production, dev/test, and so on. It is important to understand when defining policies that the configuration is usually a trade-off of performance vs. utilization. An example of this is shown in the following diagram: