How Many Virtual Desktops Can a Physical Server Handle in a VDI Environment?

By Hank Smith
Posted in Virtualization
On February 16, 2012

This question comes up many times from customers who are evaluating the use of a virtual desktop infrastructure (VDI) solution. Unfortunately the answer is, “It depends.” There are many variables in play that will determine that number. Taking the hypervisor (VMware, Citrix, Microsoft) out of the question, along with storage requirements (IOPS, space) it really comes down to the OS and applications.

For example, a VDI environment providing primarily Windows 7 virtual desktops will have more requirements than an environment providing Windows XP desktops. As with OS types, different applications impose different requirements on the environment. There are tools out there (for example, Liquidware Labs Stratusphere and Lakeside SysTrack) that can assist in determining the requirements for the virtual desktops.

To illustrate the question (minus factors like memory sharing, etc.), if we had a physical server with 128 GB of memory, and we provided a single vCPU and 2 GB of memory per Windows 7 virtual desktop, we would have roughly 64 virtual desktops. Please keep in mind, this doesn’t factor hypervisor host memory, networking, and storage requirements. However, today’s physical desktops typically have much more than 2 GB of memory; typically, the figures used are 3 GB of memory and 2 vCPUs per Windows 7 virtual desktop. With those numbers, we are at approximately 42 desktops per physical hypervisor server.

We go back to the answer, “It depends.” Without proper analysis of the existing physical workstations or a proof-of-concept, you are guessing the server requirements for the proposed VDI environment.

Gotham leverages its experience implementing flexible, scalable virtualization solutions for diverse environments, as well as partnerships with industry-leading vendors, to provide its clients with the VDI solutions that best fit their requirements. Contact your Gotham account manager to learn more.

Hank Smith

Hank Smith

Hank is an expert in the design, development, and delivery of cost-effective, high-performance technology solutions. As manager of Gotham’s Virtualization practice, Hank builds motivated, productive teams for Gotham’s large-scale networking and infrastructure engagements, develops implementation standards and methodologies around virtualization technologies, and manages overall design and implementation of multiple infrastructure projects.