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CHAPTER 2 Discovering Virtual Desktop Infrastructure 25 These materials are © 2020 John Wiley & Sons, Inc. Any dissemination, distribution, or unauthorized use is strictly prohibited. need. For example, if your company runs in three shifts and has 3,000 employees, each with a dedicated desktop, you don't have to size the environment to support 3,000 simultaneous desktops. You need to size it to support the maximum number of desktops that will run at the same time. Size of desktops Sizing virtual desktops is an activity that asks you to specify the number of virtual CPUs (vCPUs) that each desktop will have, the amount of RAM, and the amount of disk space. But the aggregate math isn't quite as simple. For example, if every desktop will be configured with 80GB of disk capacity, you can't assume that 3,000 desktops will require 240,000GB (240TB) of capacity. Technologies such as deduplication, thin provisioning, and linked clones (explained later) may allow you to dramatically reduce your storage capacity need. The only way to get close is to do a small pilot and see what happens. The same goes for RAM. Some hypervisors do tricks with RAM to reduce RAM consumption and increase virtual machine density. Again, you need to experiment. Application types The kinds of applications you run are critical. If you're only supporting email clients, you can increase the number of desk- tops per host. Desktops with more demanding applications also require more resources, which reduce the overall density of the VDI environment. Graphics needs GPUs are becoming all the rage and they are popular in VDI envi- ronments. GPUs can allow hosts to offload some of the graphics processing needs, which can be significant, to the GPU, thereby increasing the density of the desktops on the host. This solution only works to a point. Eventually, the GPU itself gets saturated, so you need to watch overall performance. The beauty of a VDI environment is that adding hosts is a simple matter if you begin experiencing performance problems. You can just add a node and reduce the density of the existing hosts to free up capacity.