As a consultant, I work with customers everyday to provide them with the most cost-effective solution to meet their needs. Since the advent of hypervisors and virtualization in general (including streaming technologies), these customers' questions have become more complex as they are tasked with implementing more creative solutions to meet their companies' dynamically changing needs.
Specifically, they are tasked with doing more with less while providing room for growth and flexibility in their infrastructure. Today the majority of environments are set up in distributed PC scenarios. However, the paradigm is slowly shifting and customers are asking more questions than ever about desktop virtualization versus distributed PCs.
A case for desktop virtualization
There are several methods of desktop virtualization (remote PCs). One is called "server-based computing," which allows the user to deliver desktops and applications from the server. This technology has been around for about 10 years and has been widely accepted. With this technology, users connect to the terminal server desktop or published applications using either Citrix's ICA protocol or Microsoft's RDP. That lets you fully utilize your server resources because all the processing remains on the server.
In addition, storage is usually located in the data center, right beside the terminal/Citrix servers and this typically allows for faster access to the data. It is also currently the most scalable solution because you can get more users on one server versus the scalability of virtual machines.
VDI (virtual desktop infrastructure)
The most widely implemented version of VDI is VMware's VDI solution. Typically, it involves putting Microsoft Client or Linux client operating systems on a hypervisor infrastructure like VMware or Citrix's XenServer in an isolated environment, which are called virtual machines. (In the industry, this scenario is referred to as virtual desktop infrastructure). Initially, hypervisors were leveraged to consolidate server operating systems such as Microsoft Server 2003. In the last couple of years that has extended to the end user's operating systems, leading to VDI.
In a VDI architecture, the end users' OS is located on a server or alternately a blade PC or workstation blade in the data center. Because of this, the need for desktop PC support decreases significantly. This is particularly true if you incorporate a desktop replacement project, replacing PCs with thin clients, which is, in my experience, what most companies consider when they are looking at migrating from distributed PCs to remote PCs.
Thin clients are access devices with an embedded OS and no moving parts. Administrative overhead goes down significantly with thin clients. If one of the thin clients becomes unusable, you can just unplug it and plug in a replacement. (They are practically plug and play.) Alternately, companies may repurpose their PCs and lock them down with GPO policies until their end of life and then replace them with thin clients. Thin client life spans are typically five to seven years, unlike three years for PCs.
Another benefit that remote PCs have over distributed PCs is facility usage costs -- that is, if you migrate to thin clients. Thin clients typically burn at 6 to 30 watts per device while distributed PCs burn at 150 to 350 watts per device. This is a significant savings on power consumption over the life span of thin clients. (Going Green is becoming a very compelling concept for companies and thin clients play a major part in that process.)
Hospitals, financial institutes and schools are early adopters of this technology because of HIPAA and SOX compliancy issues surrounding data security and auditing. Managing all the end users' OSes centrally allows companies to control the data that users would typically save to their local machines (desktop PCs or laptops). A major concern for companies today is the misplacement or theft of a user's desktop PC or laptop, allowing confidential or intellectual property to get into the hands of a third party who could leverage it for malicious purposes.
It also ensures that if a company is ever audited, it can make sure that it is compliant with SOX or HIPAA standards. This is one of the main reasons financial and medical organizations tend to be the early adopters of this technology. If any of their customers' or patients' personal information gets into the public domain, the company is vulnerable to lawsuits.
Each company's environment is unique. As an engineer you need to consider all of the material here when creating an ROI case for your decision makers. Value-added resellers (VARs) can help you build the case with tools for auditing, planning and calculation spreadsheets. Try leveraging your partners to assist you in gathering this information and to position it with your management. They do it all the time and have it down to a science.
About the author: Glenda Canfield, MCSE, is an expert on virtualization in the enterprise and has more than 10 years of experience designing and supporting on-demand data centers. Her experience includes large distributed data centers with concurrent Citrix connections in the tens of thousands. Glenda is also an expert speaker, with experience presenting at major Citrix and desktop virtualization conferences, including Citrix Summit 2008 and BriForum 2008. Glenda currently works for ComputerTech, based in Richardson, Texas.
