There are several factors that must be considered when calculating memory requirements; these factors include the amount of memory required to support the current workloads, the amount of memory required to support future growth, the amount of memory required for virtual machine memory overhead, and the maximum memory utilization threshold.
As with CPU requirements, the discovery information from Chapter 3, The Design Factors, will also be used to calculate the memory requirements:
Currently, there are 100 physical servers, each hosting a single application. Each application services 10 customers.
The business expects to add 50 new customers over the next year.
Support growth over the next five years.
Each application server is configured with 8 GB of memory. The peak usage of a single application server is approximately 65 percent or around 5.2 GB.