Appendix D: Capacity Management : Organization Virtual Datacenter-Specific Capacity Forecasting
Organization Virtual Datacenter-Specific Capacity Forecasting
Capacity forecasting consists of determining how many virtual machines are expected to be deployed during a specific time period of the organization’s choosing. The time period used for the virtual machine forecast should correspond to the budgetary process. Capacity provisioning is concerned with determining when an organization virtual datacenter must be expanded in order to maintain capacity.
VMware recommends that organizations perform two forecasting functions over time.
*Capacity trending – Using historical virtual machine capacity and utilization data, it is possible to predict future capacity requirements.
*Capacity pipeline – Understanding future user resource requirements for virtual machines through IT and LOB projects provides the necessary information for understanding future capacity requirements.
Over time, capacity trending can be used to assist with the forecasting of virtual machine provisioning needs. It uses historical information to determine trends and validates the virtual machine forecast based on pipeline data.
Capacity provisioning depends on determining the point of expansion for the organization virtual datacenter. This is based on determining a point of resource consumption at which the process of procuring and expanding the organization virtual datacenter must begin so that reserve capacity is not exhausted before the additional capacity is available. In the vCloud context, this can be considered to be dependent upon the time it takes to process the purchase request for additional organization virtual datacenter resources. Provisioning time can be assumed to be zero but depends upon specific contractual agreements with the service provider.
The next sections describe recommended steps to perform capacity trending and to determine a point of organization virtual datacenter expansion.