Fortunately, we have an eight-step process to help you gauge the potential returns on a VDI deployment by examining organizational structure, existing virtualization adoption, security, employee productivity, support, disaster recovery, and power savings.
1. Determine whether the cost of a more-expert data center staff can be offset by needing fewer people to administer desktops. One thing most early adopters we've worked with agree on is that building and maintaining virtual desktop images and troubleshooting VDI problems require a well-trained IT staff. Deploying a limited number of identical workstation images en masse will reduce the overall amount of labor required to maintain desktops, but the technical expertise of the people performing those functions must increase dramatically. If you now use machine-imaging techniques to simp-lify and homogenize workstation deployments, your staff should easily adapt to VDI problem-solving and maintenance.
2. Determine how much desktop customization is required. The best candidates for VDI are organizations that don't have a lot of user groups and whose employees have uniform application requirements. At small companies, workers often fill multiple roles, so their desktops are highly customized; that means many images must be maintained. And this translates to management complexity in the data center.
3. Determine your current level of virtualization adoption. If you're already virtualized at the server level, desktop virtualization becomes a more attractive proposition for several reasons. Whether your vendor is Citrix, Microsoft, Sun, or VMware, odds are that your existing virtualized servers can be used to provide fault tolerance and better availability for your virtual desktops. In some cases, where the server environment is underutilized, it may even be possible to support VDI with minimal additional server purchases.
4. Determine your security and compliance posture as it pertains to desktops. If security is of paramount importance, desktop virtualization can bring major, cost-effective improvements. By centralizing desktop resources in a secure data center, it's much easier to keep sensitive information from leaving the organization. Of course, depending on whether you use all thin clients or have some older PCs mixed in, data may still leak out through flash media, removable hard drives, and other peripherals, so standard endpoint security software should still be employed in tandem with VDI.
In addition, thin clients use only a few protocols to make and sustain connections to desktop images in the data center, in contrast with typical desktops that may use hundreds of different protocols, depending on applications. Fewer protocols always equals better security.
5. Determine if you'll buy thin clients or continue to use PCs. Yes, buying thin clients adds considerably to the cost of your VDI rollout. But using your existing PCs as virtual desktop endpoints has real downsides. First, it negates the security advances of VDI because data can be cached locally. Second, IT will still need to perform maintenance on physical PCs in addition to maintaining your virtual desktop images. And finally, you'll lose thin-client-related power savings, which can be significant in large companies.
The downside to thin clients, of course, is that the devices can't be used offline. While users of fat- client desktops who lose Internet connectivity may not be able to access network resources, they're still able to use some applications, work on local copies of files, and potentially get something done. For shops whose client endpoints are computers rather than thin clients, major vendors do offer offline virtual desktop technology, for an additional charge.
6. Are you willing to put policies in place--and enforce them? To realize the promise of reduced support costs, you'll need to tailor policies to VDI. For example, a user with administrative rights who installs software on top of the base image issued to her will find this software missing next time she checks out a virtual desktop. And, policies must be implemented to ensure data is never accumulated on desktop images, again, because it will be lost when the desktop is reissued. Document and desktop folders must be redirected to network shares, mail must be stored on mail servers, and users should be restricted from accessing local drives; otherwise, you risk data loss that no backup tape can solve.
7. Determine if an improved endpoint disaster recovery strategy can yield savings. Because desktop images and configuration settings are stored on your SAN with other critical business data, these images can be replicated or backed up directly from the data center. In the event of a disaster, workstation pools could be brought online in a secondary data center, possibly thousands of miles away, and employees wouldn't know the difference. Now that's what we call ROI.
8. Determine potential power savings. For large organizations with hundreds of desktops, power savings alone can justify the cost of desktop virtualization. Published energy consumption for an average thin client with an LCD monitor is about 100 watts. Desktop computers consume two to five times that amount of electricity. Now, vendors will tally these numbers and tell you that you'll save X watts of power per terminal, but that's not an accurate picture because your desktop application load will be consuming power on the server side instead. The good news is that by fine-tuning your data center workload, you can operate the servers dedicated to VDI at very high rates of utilization, which further maximizes power savings and efficiency.