Virtualization: From Hardware-Lock- In to Software-Lock-In

Transkript

1 Virtualization: From Hardware-Lock- In to Software-Lock-In Marius Alexander 7. Fachsemester, Bachelor Matrikelnr: Anschrift: Heidornstr. 10, Hannover Mobil: +49 (0) Betreuer: Karsten Sohns Institut für Wirtschaftsinformatik (IWI) Leibniz Universität Hannover

2 Seite 2 von 43 Inhaltsverzeichnis 1 Introduction Author's Note Definition of virtualization Types of virtualization Desktop Virtualization Types of Desktop Virtualization Architecture of VDI Desktop Virtualization and VDI The status quo Pros and Cons Management, flexibility, maintenance and support Security Costs Network, storage and printing User Market Review Influence of Desktop Virtualization on corporate culture BYOC Conclusion List of Sources Interviews Sources and Website on CD... 43

3 Seite 3 von 43 List of Figures Figure 1: VDI, Local Virtual OS and Terminal Services... 9 Figure 2: Architecture of VDI Figure 3: Hype Cycle for Virtualization...12 Figure 4: Do you plan to use virtual desktops...14 Figure 5: Are you satisfied with Desktop Virtualization?...14 Figure 6: How important are each of the following areas of virtualization to your company over the next months? Figure 7: Importance of virtualization technologies Figure 8: Do you think Desktop Virtualization is a consistent continuation of IT consolidation?...16 Figure 9: What are the drivers for Desktop Virtualization?...16 Figure 10: Lifecycle of traditional desktops and VDI Figure 11: Will you need to track on user access events in your VDI environment?...19 Figure 12: Have you considered how you will secure this environment?...19 Figure 13: VMware View Figure 14: XenDesktop: HDX and FlexCast Figure 15: FlexCast... 25

4 Seite 4 von 43 1 Introduction Virtualization is a technology with a lengthy history, it is dating back to work by IBM in the late 1960s and early 1970s. It was implemented in order to split up massive mainframe machines into separate virtual machines with the objective of maximizing the available mainframe computers efficiency. At that time mainframes could only work on one process at a time, this problem was solved by splitting up the mainframe into several entities. During the 1980s the x86 instruction set architecture became dominant and the client-server model was established. This helped administrators to connect several low cost workstations that shared their resources with powerful servers. From that point virtualization was no longer required. This trend was supported by the massive use of operating systems like Windows and Linux in the 1990s. But this underlying trend led to manifold problems by the massive growth of computer technology and IT, for instance rising costs for physical infrastructure, IT management and maintenance. Furthermore security and disaster protection were insufficient and utilization of hardware infrastructure was low. (cf. Menken & Blokdijk, 2008, pp. 8-10) (cf. Ruest & Ruest, 2009, pp. 4-9). This changed at the end of the last millennia with VMware s introduction of their first hardware virtualization application for x86 based systems called VMware Workstation (cf. Delap, 2008). The progressive development of virtualization led to various forms of virtualization (see 1.2 types of virtualization). One of these current trends in virtualization is Desktop Virtualization respectively Virtual Desktop Infrastructure (VDI). Referring to the title of this paper From Hardware-Lock-In to Software-Lock-In the goal of this term paper is to show developments, standards and vendors of desktop virtualization and their impact on IT in companies and organizations Author's Note There are innumerable authors, books, websites and many other additional sources which deal with the theme of virtualization thoroughly. These authors are defining and explaining the topic in their own way. These opinions and ideas do often not match with each other or are contradictory.

5 Seite 5 von Definition of virtualization In computer science a clear definition of the concept of virtualization is not possible due to the fact that the term is differently used in many different contexts (cf. Wikipedia, de.wikipedia.org, 2009). According to that there are various ways in defining virtualization. A very open attempt is: Virtualization is a technique for hiding the physical characteristics of computing resources to simplify the way in which other systems, applications, or end users interact with those resources. (Bolton) Delap says that In computing, virtualization is a broad term that refers to the abstraction of computer resources. Virtualization hides the physical characteristics of computing resources from their users, be they applications, or end users. This includes making a single physical resource (such as a server, an operating system, an application, or storage device) appear to function as multiple virtual resources; it can also include making multiple physical resources (such as storage devices or servers) appear as a single virtual resource... (Delap, 2008) Hoopes mentions that the term virtualization has been coined by manufacturers and vendors for the purpose of categorizing their products. From his point of view that makes sense if their claims meet the following requirements: Add a layer of abstraction between the applications and the hardware Enable a reduction in costs and complexity Provide the isolation of computer resources for improved reliability and security Improve service levels and the quality of service Better align IT processes with business goals Eliminate redundancy in, and maximize the utilization of, IT infrastructures (Hoopes, 2009, p. 2) In Hoopes mind virtualization is best defined by Singh: A framework or methodology of dividing the resources of a computer into multiple execution environments, by applying one or more concepts or technologies such as hardware and software partitioning, time-sharing, partial or complete machine simulation, emulation, quality of service, and many others. (Singh, 2004) 1.3 Types of virtualization In literature one can find different types of virtualization. For this reason it is hard to find a clear overview of the topic. The German site of Wikipedia divides virtualization in Hardware- Software and Network-Virtualization (cf. Wikipedia, 2009).

6 Seite 6 von 43 Delap mentions that the term is widely applied to a number of concepts which include Server Virtualization; Client, Desktop, Application Virtualization; Network Virtualization; Storage Virtualization and Service/Application Infrastructure Virtualization (cf. Delap, 2008). Ruest (cf. Ruest & Ruest, 2009, pp ), Hoopes (cf. Hoopes, 2009, pp ), Runge et al. (cf. Runge, et al., 2009) and (cf. Fruth, 2009, pp. 4-8) are in common that the most important types of virtualization are Server, Storage, Network and Application respectively Desktop Virtualization. These types of virtualization are defined below. According to the theme of this paper Desktop Virtualization will be focused later on. Server Virtualization Server Virtualization is the most common form of Virtualization and in most cases what people think when the term virtualization is referenced. A reason for that is the huge success of Server Virtualization over the last years. It can be separated into four categories (Hoopes, 2009) (Runge, et al., 2009): Full Virtualization Paravirtualization Operating System Virtualization Hardware Virtualization or rather Native Virtualization Storage Virtualization Storage Virtualization defines the process of merging physical and logical storage so that it appears as one single storage pool. (cf. Ruest & Ruest, 2009, p. 27) Network Virtualization Network Virtualization describes several approaches of combining hardware and software network resources and network functionality into a single logical entity. (Runge, et al., 2009) The most popular forms of network virtualization are Virtual LAN (VLAN), Virtual IP (VIP) and Virtual Private Network (VPN). (cf. Hoopes, 2009, p. 30) Application Virtualization Application Virtualization describes the encapsulation of applications from the operating system they are installed on in order to improve portability, manageability and compatibility. That means that virtualized software is not installed in a traditional way, although it is executed as it is. As a result (of this) the application is fooled at runtime into believing that it is directly interfacing with the original operating system. (cf. Hoopes, 2009, p. 31) (cf. Wikipedia.org, 2009)

7 Seite 7 von Desktop Virtualization As it is mentioned in the author s note it is quite complicated to give a clear definition of Desktop Virtualization that satisfies all opinions and ideas that are stated by different authors about the topic: The IT industry makes heavy use of buzzwords and ever changing terms to define itself. (Delap, 2008) In case of Desktop Virtualization there are several buzzwords and definitions in use, for instance: Virtual Desktop Infrastructure (VDI), Server-based Computing, Client- Virtualization, Client-/Server-Hosted Virtual Desktop (HVD), centralized desktop virtualization, Virtual Desktop, Desktop as a Service, Enterprise Desktop Virtualization (EDV) etc.. A simple attempt to define Desktop Virtualization is given by Brian Madden: At its most basic level, virtualization is separating the physical from the logical, so therefore desktop virtualization is separating the physical desktop device (laptop, desktop, etc.) from the logical desktop software (Windows). (Madden, 2009) In addition to that Madden mentions that VDI is just a part of Desktop Virtualization and not the only type of Desktop Virtualization. This opinion is supported by Dave Sobel. Furthermore he says that Virtual Desktop Infrastructure (VDI) is the use of virtualization to run desktops in a data center. The desktop is delivered to the user on demand and managed centrally, and it delivers the same user experience as a standard PC. (Sobel, 2009) As one can see VDI is not synonymous with Desktop Virtualization although authors often use it as a similar term. This shows that there is a need to have a closer look on Desktop Virtualization. Santosus differentiates Desktop Virtualization into Hosted Desktop Virtualization and Client Virtualization. Client Virtualization means that hypervisor software is installed on the client device. This allows one desktop to run multiple operating systems. Hosted Desktop Virtualization means that a server in a data center hosts virtual machines. Users connect to the server via a connection broker. (cf. Santosus, 2008) Technology research and advisory company Gartner gives a clear definition of Hosted Desktop Virtualization: A hosted virtual desktop is a full, thick-client user environment (operating system and applications) run as a virtual machine (VM) on a server and accessed remotely through a window on a remote device. All software execution takes place on the server where the VM is hosted, and only the presentation layer for the VM is sent to the remote device. Access can be via a browser window, a remote session on a PC or a thin-client terminal. HVDs centralize user applications and data, but they differ from traditional serverbased computing (SBC), also referred to as "thin client" computing, because applications run

8 Seite 8 von 43 in a single-user environment. An SBC environment is multiuser, which can cause support issues and require re-engineering of applications. (Moore, 2009) According to Valovic (cf. Valovic, 2009), Ruest (cf. Ruest & Ruest, 2009, p. 249) and others, VDI and Hosted Desktop Virtualization define quite the same. The term Virtual Desktop Infrastructure (VDI) was originally developed by VMware as a product name for desktop virtualization. (cf. Sommergut, 2009) Types of Desktop Virtualization Kevin Fogarty classifies the approaches of Desktop Virtualization into five types (cf. Fogarty, 2009). It should be noticed that Fogarty refers to Application Virtualization as a part of Desktop Virtualization (see Remote Virtual Applications and Local Virtual Applications). Remote Hosted Desktops The term Remote Hosted Desktops describes the approach of terminal services. An operating system or application just exists once on the server but can be run by several people at the same time. Clients user log into it by using connection broker software, which is installed on the client machine. Examples for vendor offerings: Software: Citrix XenDesktop; Wyse ThinOS; Microsoft Remote Desktop Services; Microsoft Enterprise Desktop Virtualization (MED-V); VMware View Manager. Hardware: Pano Logic Device, Remote; ncomputing thin clients; Wyse thin clients; Sun Ray Ultra-Thin client; Symbiont Network Terminal; Rangee Thin Client Remote Virtual Applications Remote Virtual Applications differs from Remote Hosted Desktop because they only require a browser or standard web protocols to create a secure connection to a server. Examples for vendor offerings: Citrix XenApps; Microsoft Remote Desktop Services; VMware View; VMware ThinApps. Local Virtual Applications The multitude of installed software packages often need specific versions of software system libraries. This produces dependencies and conflicts between applications. Local virtual applications can be run within a sandbox that isolates the application from the operating system. Examples for vendor offerings are: Citrix XenApp, Wyse TCX, VMware ThinApp, Microsoft Application Virtualization.

9 Seite 9 von 43 Remote Hosted Dedicated Virtual Desktops In difference to Remote Hosted Desktops, Remote Hosted Dedicated Virtual Desktops connect to one virtual machine (VM) hosted exclusively for the user on a server (with several more VMs) or a blade PC in the data center. Furthermore it can be differentiated into streamed (downloading parts of a software and executing it on the client machine by using its processing power) and hosted remotely (Hosted Virtual Desktop/VDI). Hosted remotely: Examples for vendor offerings: Citrix XenDesktop; Wyse ThinOS; VMware View; Microsoft Remote Desktop Services; Microsoft Enterprise Desktop Virtualization (MED-V) Streamed: Example vendor offerings: Citrix XenDesktop, XenApp, XenProvisioning; Wyse TCX; VMware View Manager, ThinApps, Composer; Microsoft VDI suite. Local Virtual OS There are two major versions for Local Virtual OS both need a hypervisor. The first one runs a virtual machine in the existing operating system which is separated from the hard- and software outside of the VM (type 1). The second option is to run a hypervisor on the machine s BIOS. This allows users to run multiple OS without a host OS ( bare-metal, type 2). Examples for vendor offerings: Citrix Dazzle and Receiver, Wyse Pocket Cloud, TCX, VMware View Client Virtualization with Offline Desktop (Experimental); Microsoft VDI suite, Microsoft Virtual PC Figure 1 shows a scheme of relevant types of Desktop Virtualization by Fruth. (cf. Fruth, 2009) Figure 1: VDI, Local Virtual OS and Terminal Services (Source: Fruth, 2009; adopted by the author)

10 Seite 10 von Architecture of VDI Fujitsu Siemens describes architecture of VDI/HVD as shown in Figure 2. Gernot Fels says: Die Einteilung stammt leider nicht von Fujitsu, die Begriffe werden so von Analysten und auch manchen Anbietern von Virtualisierungs-SW so benutzt. (Interview by the author, 2009) Figure 2: Architecture of VDI (Source: Fujitsu Siemens, 2009) The main differences between VDI and other types of Desktop Virtualization is that in a Virtual Desktop Infrastructure the user s operating system runs in an isolated virtual machine on a server where it is executed. A virtual machine (VM) is a software implementation of a computer that appears to the network as a separate physical machine and behaves like it. Multiple VMs can be run isolated from each other on a server. For that a software layer is needed, called Virtual Machine Monitor (VMM) or Hypervisor. Furthermore VDI needs a software program that allows the end-user to connect to an available desktop. This so-called connection broker has the task to validate the user, to provide a connection between the VM and the client, to monitor and to handle the status of a user (active or inactive). Moreover clients receive their user interface via standard protocols over IP, for example RDP. Finally, several types of client devices can be used in a VDI, for instance Thin/Zero Clients, Notebooks, PDAs, mobile Phones etc. (cf. AMD, 2008) A more detailed view on architecture of VDI and solutions is given in chapter three. Basically there are three different models of VDI (cf. Ruest & Ruest, 2009, pp ): A persistent or assigned desktop is linked to one single virtual machine. The same desktop is provided to the user each time he logs on. This model requires a lot of central storage space and does not reduce complexity of management and support. So it is

11 Seite 11 von 43 unfortunately unable to utilize the full potential of VDI. This model should only be used if the number of users is low. No persistent, volatile, or pooled desktops provide a new, generic desktop each time the user logs on the infrastructure, this consists applications and user profile data. As a result this model requires less space due to the fact that specific custom content is stored in a separate file. This model tends to be the most popular one because of its benefits related to storage and management. A persistent clone desktop is generated the first time a user logs on. From now on the user has the possibility to personalize its clone. Every time he logs back on the infrastructure the user relies on that personalized clone.

12 Seite 12 von 43 2 Desktop Virtualization and VDI In 2007 Thomas Bittman from Gartner announced Virtualization as the next big hype in IT. Moreover he added that Desktop Virtualization has even more potential than Server Virtualization to improve the management of IT infrastructure: Virtualization on the client is perhaps two years behind, but it is going to be much bigger. On the PC, it is about isolation and creating a managed environment that the user can t touch. This will help change the paradigm of desktop computer management in organizations. (Moore, Gartner.com, 2007) Now, about two years later Gartner sees Hosted Virtual Desktops/VDI on Peak of inflated expectations in their Hype Cycle (see Figure 3). According to the general concept of the Hype Cycle the number of vendors offering the technology increases. More and more enterprises start to explore if the technology may fit within their business strategies, although the majority does not take action. At this point problems of first-generation products become visible and negative publicity starts to push the technology into the Trough of Disillusionment. (cf. Gartner, 2008) Figure 3: Hype Cycle for Virtualization, 2009 (Source: Gartner, 2009) For this reason the status quo and benefits respectively pros and cons will be shown in this chapter.

13 Seite 13 von The status quo According to Gartner revenues from Hosted Virtual Desktops will increase more than 300 per cent from $74.1 million in 2008 to $298.6 million in As a result HVD will share about 11 per cent of the virtualization software market revenues. (cf. Stevens, 2009) Furthermore Gartner expect that the number of sold units will accelerate through 2013 to reach 49 million up from more than 500,000 in Revenues will grow up to $65.7 billion in That would be equal to more than 40 percent of the worldwide professional PC market. (cf. Häussler, 2009) IDC is predicting that revenues from Hosted Virtual Desktops will grow up to $1.7 billion by Besides the buzz around Hosted Virtual Desktops most analysts expect the market to experience robust growth. (cf. Valovic, 2009) This trend is confirmed by TechTarget's "Virtualization Decisions 2009 Purchasing Intentions Survey". The more than 900 IT professionals show a growing interest in Desktop Virtualization. Although 35% are not interested in Desktop Virtualization, the number of not interested is decreasing from 43% in Their reason for interest is primarily driven by management benefits. About 20% of all respondents are evaluating Desktop Virtualization this year another 20% plan to do so in % have deployed it in departments, 5% companywide since The majority of companies (69%) said they use VDI/HVD, about 49% use Terminal Services and 40% use application virtualization products. Besides this cost remains the biggest obstacle. 24% said that the technology is too expensive, 20% won t get the budget approval. 24% are thinking that their servers can t handle the masses of virtual machines and are not willing to buy new servers. In addition to that, 24% of the respondents added that they would wait until product options are fully developed. (cf. Botelho, SearchVirtualDesktop.com, 2009) Unfortunately it was hard to find recent surveys due to the fact that market research institutes demand a lot of money upfront. According to a survey by cio.com 25% of enterprises already use Desktop Virtualization. Besides this 36% do not plan to use virtualized desktops (see Figure 4). Moreover cio.com stated that there are fewer smiling faces by reason that 60% are satisfied or very satisfied (see Figure 5). (cf. McLaughlin, 2008)

14 Seite 14 von 43 Figure 4: Do you plan to use virtual desktops (Source: cio.com, 2008) Figure 5: Are you satisfied with Desktop Virtualization? (Source: cio.com, 2008) According to a survey of IDG 39% of respondents prioritize Desktop Virtualization compared with 68% for Server Virtualization. 42% say that they will deploy Desktop Virtualization within two years (until first quarter of 2010) (see Figure 6). 37% do not know if they will ever deploy Desktop Virtualization (see Figure 7). (cf. IDG, 2008)

15 Seite 15 von 43 Figure 6: How important are each of the following areas of virtualization to your company over the next months? (Source: IDG, 2008) Figure 7: Importance of virtualization technologies (Source: IDG, 2008) In fact these surveys show that respondents think critical about Desktop Virtualization. Although it seems that IT managers start to realize its potentials. Centracon, a german management and technology consultancy asked more than 300 medium and large enterprises in 2008 and 2009 if they think that Desktop Virtualization is a consistent

16 Seite 16 von 43 continuation of IT consolidation. The number of supporters increased from about a third to nearly a half. (cf. Centracon, 2009) Figure 8: Do you think Desktop Virtualization is a consistent continuation of IT consolidation?; (Source: Centracon, 2008/2009; adopted by the author) Furthermore drivers of Desktop Virtualization are mainly easier management, higher flexibility, security and cost savings (see Figure 9). These drivers will be focused in the following. Figure 9: What are the drivers for Desktop Virtualization?; (Source: Centracon, 2008/2009; adopted by the author)

17 Seite 17 von Pros and Cons For about the half of respondents of the Centracon survey (see Figure 9) desktop virtualization is part of an overall virtualization strategy. But it has to be said that advantages of desktop virtualization and for instance server virtualization are not the same: "Desktop virtualization is a very different beast and should not be treated as simple enhancements to the server strategy," says Natalie Lambert, principal analyst at Forrester Research. "The drivers are entirely different and the environment will present new challenges to those experienced with server virtualization." (Dubie, Infoworld.com, 2009) Heiko Kapeller, IT Systems Administrator at Vorsorge Luxemburg Lebensversicherung S.A., points out the benefits: Da wir seit längerem im Serverumfeld Virtualisierung einsetzen, war der nächste Schritt die Analyse, ob sich Desktop-Virtualisierung einsetzen lässt. Da ein Großteil der Arbeitsplätze im Haus seitens der Hard- und Software gleich anspruchsvoll sind, war die Idee diese zu virtualisieren und die vollen Möglichkeiten der Flexibilität von virtuellen Arbeitsplätzen zu nutzen. Also stand im Vordergrund die Managebility und an zweiter Stelle die Kostenfrage. Da neue Hardware hätte angeschafft werden müssen, sind wir weg von Fat-Clients und hin zu Thin-Clients gewechselt. (Interview by the author, 2009) Management, flexibility, maintenance and support VDI simplifies desktop management and reduces the typical problems of distributed desktops. Every user is provided with a virtual desktop reflecting his or her profile and this is managed centrally. Every endpoint device for instance desktops, thin clients, web clients and Pocket PCs or mobile phones are provided centrally. It is possible to rebuild an entire operating system in minutes. This leads to higher scalability and flexibility. IT administrators are not forced to fix problems at the end users workplace. The endpoints only have to provide a remote desktop connection to the virtual desktop. This tends to increasing productivity for IT employees and end users alike. Moreover desktops are delivered and maintained more quickly by transforming the desktop lifecycle (see Figure 10) and its number of components. Generally administrators have to procure, image, secure, deploy and after all to monitor, maintain, back up and retire fat clients. With VDI it is possible to create an image which is provided as a reference computer, personalize it for users and then monitor and update it. This includes security updates and new software, or regular upgrades to existing software. A high degree of standardization combined with centralized data and applications increases the efficiency. (cf. TechTarget, 2009)

18 Seite 18 von 43 Figure 10: Lifecycle of traditional desktops and VDI (Source: SearchEnterpriseDesktop.com/TechTarget (2009). Desktop Virtualization: An Expert Guide to the Benefits and Challenges; adopted by the author) Desktop virtualization also makes it easier to get new computers up and running. Many computers need custom drivers to work properly, and setting these up can be timeconsuming. With desktop virtualization, the VM being pushed to the new computer would already have the appropriate drivers installed, said Scott Gordon, sales engineer. (Shavit, 2008) Although VDI has several advantages in management, maintenance and support it carries risk: The use of optimized desktop hardware and centralized computing allows previously incompatible applications to share the same physical machine. While working through the virtualization planning process, IT decision makers should be aware of one critical piece of the puzzle - virtual desktop licensing. (Kusnetzky, 2009) Besides the fact that VDI offers possibilities to track software usage and licenses it is still often not clear if licensing is appropriate because licensing rules vary for each supplier of software products. (cf. Kusnetzky, 2009) Security Security is one of the major benefits of VDI while virtual machines are separated from other VMs and the computer s hardware. Furthermore VDI enables administrators to lock down user s desktops. This leads to a higher security level since applications and data are not stored locally with the potential to expose viruses and spyware. (cf. Shavit, 2008) In addition the risk of data theft decreases because they are storage in the data center and not on an endpoint device. Jack Wilson, enterprise architect at Amerisure Insurance explained:

19 Seite 19 von 43 "I'm not worried about catching something off a laptop because I'm just borrowing the laptop's screen and keyboard. In a traditional VPN model, it would be a problem because you would be connected to my network." (Kaneshige, Infoworld.com, 2008) Imprivata, a company for Authentication and Access Management asked 132 organizations in 2009 how they plan to secure their VDI environments. More than two third says that they will track on user access events, only 7% will not. (cf. Imprivata, 2009) Figure 11: Will you need to track on user access events in your VDI environment? (Source:Imprivata, 2009) 37% will secure their environment by additional strong authentication, 21% by using the security that comes with the VDI system. Figure 12: Have you considered how you will secure this environment? (Source:Imprivata, 2009)

20 Seite 20 von 43 In addition to that Eric Schultze gives five hints how to secure a VDI. These relate to patching, configuration, firewall, application control and antivirus. (cf. Schultze, 2009) Costs Respondents, vendors and IT shops often accentuate that costs are a significant reason for implementing VDI. But cost-effectiveness has to be pointed out from different perspectives. As it was mentioned before VDI offers administrators possibilities to reduce costs for management and support. Michael Keen mentions that: There are high cost and resource demands that come with managing a wide variety of client form factors, multiple generations of operating systems and hundreds of applications. Some well-managed PC environments require constant maintenance and support to repair problems and retain compliance with corporate policy. Desktop virtualization allows for large, global companies with thousands of PCs to better manage their clients because of the reduced dependence on specific hardware and operating system configurations. (Keen, 2009) Besides this acquisition cost remains the biggest obstacle for companies. Particularly with regard to costs for software and licensing VDI isn t as cheap as commonly accepted. Tony Wilburn, a senior systems engineer at Betis Group Inc., arguments: "People are used to getting Windows basically for free with their PC purchase. With a VDI virtual desktop infrastructure implementation, you have to account for the cost of VMware View or competitors' products and for Windows licenses. These additional costs along with the purchase of some type of management software will drive the costs up to the cost of a traditional PC." (Botelho, SearchVirtualDesktop.com, 2009) Moreover Botelho calls in question if the benefits of VDI really outweighs the costs for it. According to calculations by Christian Metz, director of information technology for the Orange County United Way, a Virtual Desktop Infrastructure with physical server (VMware ESX host), VMware View client, a Wyse thin client and Microsoft VDI licensing will cost about $1,078 per unit. (cf. Botelho, SearchVirtualDesktop.com, 2009) Also, Denise Dubie refers to analyst information which say that choosing virtual desktops can cost 150 to 250 percent more than traditional PCs. But as well it has to be said that a virtual desktop lifecycle can least about six years, a traditional PC rather lasts three years. (cf. Dubie, Infoworld.com, 2009) Jens Siebenhaar, Director of IT at REWE Group states: Eine Umstellung auf Thin Clients wäre für uns, bezogen auf den Lebenszyklus der bestehenden Desktop PCs, nach den Gesichtspunkten von Return on Invest nicht effizient. Deshalb werde wir uns für den