If your users complain that their virtual machines are running slow, you may want to find the reason for their complaints. You also want to know how your vSphere environment is performing, to see if additional hosts are necessary to keep your systems running smoothly. In PowerCLI, you can use the Get-Stat cmdlet to retrieve statistical information that is available on the ESXi hosts and vCenter Servers.

VMware vCenter Servers keep statistical information about the performance of the virtual machines, hosts, resource pools, and so on. This statistical information is retrieved by the hosts in real time and aggregated in four statistical intervals on the vCenter Servers. The real-time information is collected by the hosts with a collection frequency of 20 seconds and kept for 1 hour. The aggregated information is stored in the database of the vCenter Server.