I am sure there are many people who would have worked on VMware vCenter Operations Manager and used this as a component to monitor their VMware Infrastructure. But when ever you use it, you must account that the vCOPs itself will take certain amount of physical resources that includes, CPU, Memory, Storage & Networking. In generic term networking is not the hard, however other three are the major components to consider.
Consider the vCOPs vApp as two VMs (UI VM & Analytics VM) and add that to your overall VM design strategy, including consideration for the disk size, CPU & Memory. It will add these resources to your overall VM design strategy. The vCenter Operations Manager vApp consists of two virtual machines with the same basic virtual machine layout. Both virtual machines have a system disk which is sized at 8GB which should not be resized. On initial deployment, within a logical volume managed by a logical volume manager, both virtual machines have created a 120GB disk each.
Sizing of a vCenter Operations Manager environment can be challenging. In this entire post we will assume some basic consideration. Core CPU speed for the physical host is 2GHz, each VM will produce 250-300 metrics each, a physical host will bring in 1200-1500 metrics. As you can see there is a variation and this is because the number of metrics depends not only on the virtual machine itself, they depend on soft values such as the number of virtual CPUs, memory, number of network adapters, and virtual disks. Each of these components usually brings at least one metric, but can also provide multiple metrics.
You also need to consider the consolidation ratio in your environment when sizing your vCOPs. If you use vCenter Operations Manager only with vSphere and no other additional adapters, you can use the formula shown below. This formula is only used to estimate the amount of expected metrics, in order to size the vApp correctly.
Environment size: metrics = (1350/10 x consolidation_ratio) x hosts + 275 x VMs
Data retention: storage[GB]= ((metrics x 16)/(1024 x 1024 x 1024)) x interval x 12 x 168 x 4.33 x (months+1) x 1.2
Additional adapters: Metrics per resource