To support the service offerings, it is important to determine the infrastructure’s capacity and scalability. The following models determine how the resources are allocated:

To determine the appropriate standard units of resource consumption, the vCloud service provider can analyze current environment usage, user demand, trends, and business requirements. Use this information to determine an appropriate capacity distribution that meets business requirements. If this information is not readily available, it can be difficult to predict the infrastructure capacity, which depends on the expected customer uptake and usage of the workloads. However, it is useful to have an understanding of the infrastructure capacity required, based on an estimate of the different allocation models and capacity distribution of the workloads. The capacity distribution and resulting infrastructure resources allocated can be adjusted based on utilization and demand.

The following example distributes capacity based on 50% of the virtual machines for the reservation pool allocation model and 50% of the virtual machines for the Pay-As-You-Go model. The reservation pool model is applied to small, medium, and large pools, with a respective split of 75%, 20%, and 5%. Therefore, small represents 37.5% of the total, medium represents 10% of the total, and large represents 2.5% of the total number of virtual machines in the environment.

The following table lists the virtual machine count for the various resource pools supporting the two example allocation models for the virtual datacenters.

 

The following virtual machine distribution is used in the service capacity planning example:

The following table lists some examples of workload virtual machine sizing and utilization.