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Virtual vs. Vista desktop management: Calculating virtual costs, pg. 2

Estimating virtual desktop costs requires assessing server and virtualization software expenses. This tip provides a model for calculating desktop virtualization expenses and comparing them to Vista desktop management expenses. Use it to make the right desktop management decisions for your customers.

Virtual desktop costs

Moving to a virtual desktop architecture (VDA) allows users to continue to use their existing PC hardware, but as a thin-client device, connecting to a VM running on a centralized server. The virtual desktop VMs can run whatever Windows version they require, including Vista and XP. Licensing costs assume a Windows license for each VM, via either retail licenses for Vista (or XP) users not under an EA or VECD licensing, as described on the first page. Virtual desktops using VECD licensing bring savings in the neighborhood of $200 per desktop over physical desktops (or standard retail licensing).

It's important to note that a VDA does all the work on the back-end servers where the VMs run; therefore, to accurately estimate the cost of a VDA, you'll need to take into account the server and virtualization software expenses. Estimating these costs will require walking through a series of calculations, which can be modified for a customer's specific environment. As an example, based on numbers from VMware, let's assume that a server can run six to eight virtual desktops per core, with dual-socket quad-core processors totaling eight cores, yielding 48 to 64 virtual desktops per server for the back-end hardware. If we use VMware's Virtual Desktop Infrastructure (VDI) solution, built on VMware's VI3 (Virtual Infrastructure 3) server virtualization software for our example, the Enterprise license of VI3 is $5,750, so the cost for VI3 is roughly $100 per VM. According to VMware, Virtual Center (VMware's management console) can support 1,000 users per instance for $6,000, which adds only $6 per VM. For connection broker software such as VMware's Virtual Desktop Manager (VDM) or a connection manager from a third party, you should add another $50 per VM. Since storage for the virtual desktop VMs under VMware lives on a SAN, storage costs should be factored into the equation. Depending on implementation, these can be quite high, so let's assume $150 per VM for this example. Prorating the server hardware costs per VM adds roughly $350 to $400 per VM. That brings the estimated total to $700 per VM, excluding the user interface device (since in our example, the user is connecting from the existing PC acting as a thin client). To include thin-client devices for new users, add $150 to $300 per user for just the thin client or as much as $900 for an integrated all-in-one thin client (which includes the monitor and keyboard), bringing the total cost to between $900 and $1,600.

The simplified bottom-line pricing comparison (using the very rough example numbers given here) is this: Upgrading a physical desktop to Vista might cost $300 to $400 (per desktop) in hardware costs and $200 to $300 in software costs, totaling $500 to $700 per physical desktop. Delivering Vista through a virtual desktop architecture (VMware's VDI in this example) and continuing to use existing PCs as rich clients accessing virtual desktops might cost $700 per VM desktop in infrastructure costs and $23 per VM desktop, if using VECD, totaling $723 per virtual desktop.

Given this pricing example and the variations we've discussed here, initial outlay is not the compelling reason to move to a VDA. (It may be slightly better or slightly worse, depending on the specific workloads, requirements and hardware configurations of a customer's environment.) As price points come down on servers and virtualization software and as storage options for VDA continue to improve, the numbers for VDA will also improve.

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