Desktop Virtualization: an Art to Manage and Maintain Affordable PC Infrastructure

Desktop Virtualization: an Art to Manage and Maintain Affordable PC Infrastructure Asif Shabbir Department of Computer Science University of Gujrat Gujrat, Pakistan Rabtabox4u@gmail.com Fayyaz Khalid Department of Computer Science Univeristy of Gujrat Gujrat, Pakistan fayyazrao@yahoo.com Syed Muqsit Shaheed Department of Computer Science University of Lahore Lahore, Pakistan Syedmuqsit@hotmail.com Abstract The concept of Desktop virtualization was originated with Terminal Services, almost twenty five years ago but it gained a considerable popularity in last few years. With the expansion in global IT infrastructure and computational industry, companies were seriously struggling for cost effective and affordable computational solutions and PC infrastructure. Desktop virtualization technology filled the gap and now it could be seen anywhere on the globe. It allows end users to share the desktop and applications without being tied down to a specific hardware device either local or remote terminals. Companies and institutions are adopting it as a low-cost alternative of PC Infrastructure because it also allows IT departments to reduce management and support costs, along with capital expenses for desktop hardware. In this paper we shall describe the desktop virtualization and its different model. After the complete understanding of desktop virtualization we shall discuss benefits and the challenges to adopt the desktop virtualization. Punjab IT labs project and N computing (a cutting edge technology partner) will be the part of this paper as a case study for the implementation of the desktop virtualization. Keywords Desktop Virtualization; Virtualization Model; PC Infrastructure; ncomputing; I. INTRODUCTION Majority of us is familiar with the term virtualization which refers to the creation of virtual computational environment rather than actual which may involve the virtualization of OS, Hardware, Storage device or even a network resource. The roots of virtualization are backed to 1960 s when IBM was introducing new and new models of the computer system. At that time each new machine was different from its predecessor so the necessity of the virtualization was felt to emulate the predecessor machine environment on the successor ones [1].The heart of virtualization is the Virtual machine (VM) which emulates a complete particular computer system on the physical machine. Popek and Goldberg define a virtual machine as an efficient, isolated duplicate of real machine, which has no real correspondence with the hardware [2]. Fig. 1. PC Running a virtualized client Desktop virtualization is the special sub class of the virtualization. In this paper we shall focus on desktop virtualization rather than a virtualization of the complete machine. Desktops virtualization means, separation of physical location of a client device from its logical interface. In simple words, desktop virtualization is special technology which allows the users to access the desktop and applications without being coupled down to a specific hardware device either at local or remote location. Desktop virtualization is mainly based upon a session virtualization where

multiple users get connected and log into a powerful shared machine using dumb terminals. Each user is given its own desktop and a separate personal folder in which he could store his files [3]. The major advantage of desktop virtualization the reduced total cost of ownership (TCO) and ease of management. It aims to reduce the complexity and headache associated with deployment and managing client devices. Global IT companies are gradually switching toward virtualization but still there are some barriers to adopt the virtualization. Security and bandwidth are two major barriers for the adaptation of virtualization. A survey conducted by CSC in 2010, a small handful of respondents (6%) did not see any barriers to adopting desktop virtualization [4]. In preceding sections of the paper we shall discuss in detail, different model of virtualization, their benefits and challenge to adopt the virtualization. II. DESKTOP VIRTUALIZATION MODELS Virtualization is a vast term. We may create a number of complete virtual machines along with their own OS environment on a single physical machine or we may just virtualized a desktop. In broader sense there two main types of desktop virtualizations. Hosted desktop virtualization Client virtualization In hosted desktop model virtual machine is hosted at server that is located in data centre of organization while on other hand a software hypervisor is installed at client device and allow desktop to run multiple operating systems [6]. Here is the short description of different models of the desktop virtualization. A. Terminal Services Terminal services are an old-fashioned but reliable server-based model with high security and manageability. Large enterprises often use terminal services to access supported application stored on server, over network, where users are at some fixed location. Simplified manageability, improved security, low of incremental deployment cost, remote access and reduced client power consumption are the key features of the terminal services model [5]. Lack of mobility, Lower user satisfaction and single point server failure risk are the key limitations of this model [7]. PC s are good platform when only few applications use terminal services while rest of the applications is installed locally at the machine. In case of when all the applications are use terminal services then thin clients are ideal solution. Thin client usually comprises of a display and input device only, having network connectivity. All the processing and storage is taken place at centralized server. RDP (Remote display protocol) and ICA (independent computing architecture) is used to deliver a server based application image to the terminal services client [6]. Fig. 2. Terminal Services Architecture B. Virtual Hosted Desktops (VHD) Formally it was known as VDI (Virtual Desktop Infrastructure). It is a comparatively a newer model of desktop virtualization which was specifically designed to offer more responsive and user specific experience of intelligent distributed computing. It is powered with unique features of the server-based models i.e management and security because terminal services are the backbone of this model. Fig. 3. VHD Architecture The application image is delivered over network, to each client via RDP (remote desktop protocol). Each specific user receives his/her own complete virtual machine and a customized desktop to experience

customized OS and applications. Performance and responsiveness of this model varies depending upon the number of users, distance from the host, and type of application in use and even the processing power of the hosting machine. The applications with rich graphics, video streaming and VoIP are not well suited with this model due to extensive use of processing power of the host and the network bandwidth. Recent advance RDP s like HDX, remote FX, PC over IP (PCoIP) are desirable solution for such applications. For good results VHD s can also be used in combination of other models of desktop virtualization such as Application Streaming Model. Virtual hosted desktop model is energy efficient model. Increased responsiveness, customization for individual user and reduced client power consumption are key advantages of this model. There are also few limitations of this model such as performance issue as the number of users increase, applications with rich graphics and videos, lack of mobility and single point failure risk. C. Blade PC s Blade PC s are unique due to centralized computing. These are higher in manageability and security than distributed computing due to restricted physical access, software imaging polices and constrained user rights. In blade PC architecture if each user assigned a single PC blade then it is referred as (one-to-one) model on other hand if an individual PC blade serve many users then it is referred as (one-to-many) model. Blade computing is relatively costly to implement and require a long term commitment to vendor specific architecture. Blade PC s repartition the PC. The I/O devices like keyboard, display unit and mouse function on client while key devices like microprocessor, chipset and graphics are fixed on a small card that is called Blade. Multiple blades are mounted on rack at some central location. Operating system, applications and all data storage is centralized. The central unit comprising of many blades is secured in data centre of some particular organization. D. OS Image Streaming OS streaming model of virtualization ensures the centralized management of entire desktop like VHD model. This model gets the manageability and security benefits of centralization as well as it offer the responsiveness and improved performance due to the local execution of the streamed image of OS. This model is total fail where mobility is required because there is no vendor offering OS streaming with client caching. So as a result this model is not good for the applications requiring high data security because data reside on client during execution. The working mechanism of OS streaming is such that initially client is dump at startup with no operating system. OS image is pushed to the client at startup over network which is then executed at client side using client s CPU and graphics. Application data is stored centrally at data centre so clients are usually without storage hard disk. Clients use RAM exclusively. Fig. 4. One-to-One architecture of Blade PC Fig. 5. OS Image Streaming Architecture

E. Remote OS Boot Remote OS boot is a comparatively younger technology which resembles with OS image streaming. Its uniqueness is that it provides a full PC fidelity experience to its end users without demanding any back-end server infrastructure. This solution delivers the desktop virtualization while maintaining full PC and Microsoft Windows fidelity in an extremely low cost. Remote OS boot require three basic components. A client powered with Intel Core vpro processor, an Intel based storage appliance and a central administrative console. At startup client connects to the remote storage appliance via SAN (storage area network) and a type-i hypervisor is copied to the client s storage which is then loaded into client s memory. Thus a connection is established to remote central console. Remote storage is mounted to the clients just like standard SATA hard drive. The client then boots Windows OS as it would boot from its local hard drive. The simplified solution enables the end user to use off-the-shelf windows applications. Fig. 7. Application Streaming Architecture G. Virtual Containers Virtual containers are a relatively newer model of desktop virtualization that is evolving rapidly. It takes the befit of centralized management of OS image and applications. Instead of local or streamed OS, the virtual container is abstracted away from the client hardware by VMM (virtual machine manager). The presence of VMM ensures the safety against hardware compatibility issues. In this model a virtual machine images including OS and applications are created and managed centrally. Virtual machine is then streamed to the client for local execution on client based virtual machine manager. Since execution is client side in this model so application even with rich graphics are more responsive in this model. Fig. 6. Remote OS Boot Architecture F. Application Streaming/Virtualization Application streaming enables the centralized management of applications but there is no issue of responsiveness and performance as operating system is installed locally at clients. Just applications are streamed on demand and execute locally on the client [10]. Data storage can be either local or centralized. Since data reside on local machine during execution thus application streaming is not good for applications having highly secure data. Here is one thing to clear that application streaming and virtualization are usually considered same but it is not true. Application streaming is just an application delivery model. After complete streaming of application either can be installed at local machine or it may run virtually. Fig. 8. Virtual Container Architecture

III. CHOOSING AN APPROPRIATE VIRTUALIZATION SOLUTION Choosing an appropriate model depend upon a number of balanced interlinked factors. It all depends upon organizational needs analysis. An equal focus is recommended upon all the factors for the optimal solution. Following is the list of factors to consider: IT Requirements o Security o Image management o License management Infrastructure o Servers o Storage o Bandwidth User Experience o Mobility o Customization o Connectivity Application Workload o Compute Load o Graphic Load o Web server load IV. COMPARISON OF DIFFERENT VIRTUALIZATION MODELS Based upon above mentioned factors, be sure to consider user based business and application requirements. Make it sense the local versus centralized installation policy and decide which application or data is required locally and which should be kept on centralized host. Cost comparison of different appealing models is also recommended. Here is the tabular comparison of different factors and virtualization models. Terminal OS image Remote OS Application Virtual VHD Blade PC s services streaming Boot Streaming Containers Application Execution Application data storage Local device connectivity Full App. support VoIP, Rich Media Server Server Server Client Client Client Client Server Server Server Server Server Server/ Client Server/Client Yes Yes Yes Limited Yes Yes Yes Yes Support for Windows OS Yes Yes Yes Yes Off-Network Mobility option No No No No No Yes Yes Typical Nature of Terminal, PC, laptop Terminal, PC, laptop Desktop PC Terminal, desktop PC clients desktop PC desktop PC Desktop Major solution Citrix, Red Hat, ClearCube, Dell, Devon Lenovo Citrix, Dell, Lenovo provider Microsoft VMware HP, IT Citrix, Fig. 9. Comparison of virtualization models IT Business Edge conducted a peer survey on desktop virtualization familiarization and use of different virtualization model in 2011. According to the results terminal services is the most known model but most of the users are using virtual hosted desktop model at present [11].Fig. 10. Familiarization and use of different virtualization technologies

A. Virtualization Models Evaluation Different IT companies are gradually switching towards the desktop virtualization due to its unique benefits so target user/market is the real evaluator of different models and vendors. Different hardware and software vendors conduct peer researches time to time to evaluate their products band general market trends toward the particular virtualization solution. According to the peer research conducted by the Intel in Sep, 2011, the virtual hosted desktop model is the most widely used model at present [7] Fig. 10 Virtualization Models Analysis B. Market Investment Analysis Here is another way to rate any particular virtualization method that is the current market investment. It is the good way to find the market interest in any particular Virtualization method. IDG a research service group powered by AMD published a white paper to show statistics regarding current market investment in different virtualization techniques. In the peer research desktop virtualization is at the top of the list [9]. Fig. 11. Market Investment level of diff. models C. Vendors Evaluation There are a number of virtualization solution providers competing for market but Microsoft, VMware and Citrix are proven market leaders according to an IT Managers survey conducted by Intel in Sep, 2011 [8]. According to this survey still many respondents are considering smaller solution providers also but the level of their consideration is not same as market players like VMware, Microsoft and Citrix. Fig. 12. Virtualization Vendors evaluation

V. KEY BENEFITS OF DESKTOP VIRTUALIZATION Desktop Virtualization does not aim to reduce the number of PC s or Terminals like the Server Virtualization, which has been adopted by many organizations as a way to consolidate servers. Major objective of desktop virtualization is to reduce the complexity and management cost associated with maintaining and keep running client devices. Benefits of the desktop virtualization can be viewed as a number of ways scenarios. Following are the major areas of benefits: o Improved Security o Reduced Cost o Ease of Management o Productive Maintenance o Optional server/client execution o Low Power Consumption of clients o Flexibility and hardware compatibility Let us discuss them briefly. A. Improved Security In hosted desktops virtualization model VHD since data and applications run on server and streamed to the client. It provides a greater security because data and applications both reside on more secure server rather than easy to compromise clients. So on in client virtualization model, virtualization provides a protective shield against the compromising of client operating system by the hackers. B. Reduced Cost Virtualization saves your overall cast regarding hardware, software, maintenance and even software licensing. The VHD model where storage and execution is done on serve, it reduces the overall wear & tear and support cost. It is quite easy to fix the problem at server rather than fixing and providing technical support to N clients. An onsite affordable PC infrastructure could be established at very low hardware and software cost. Using N computing technology many thin clients can be connected with a single server. In this way a lot of money can be saved due comparatively low hardware cost and very low power consumption cost of thin clients. Reduced software licensing cast is another plus point. C. Ease of Management and Maintenance Since OS and applications are streamed from server to the clients in VHD model so it is easy to update single instance of OS and application image on centralized server. After updating a pre configured image is delivered to all clients from server. So it is clear that desktop virtualization is more productive regarding management and maintenance. D. Optional Client/server Execution Virtualization provides us with an option to either execute application on server or on clients. In this way we are given a chance to take the benefit of high security and easy management of the centralized storage or advantage computational power of the clients. What the IT professionals are thinking about the key benefits and the drivers of the desktop virtualization is an interesting story. IT professionals think the benefits as key drivers, reduced cost (54%), desktop manageability (54%) and software centralization (52%) [12]. Statistical comparison of key drivers and benefits of desk top virtualization is given below in the light of survey conducted by IDG sponsored by AMD. E. Low Power Consumption of Clients If we use virtual hosted desktop VHD model and access server via thin clients, a lot of power is saved. Usually a single PC consumes 380 watts of electricity but in case of thin client just 5-8 watts of power is consumed. By adding 20 watts of display unit (LCD) a full functional terminal can be operation just in 25 watts of power consumption. That is a big difference as compare to standalone PCs. F. Flexibility and Hardware Compatibility For end users virtualization provides a greater flexibility and freedom from the hardware compatibility issues. Using client virtualization, multiple operating systems to accommodate legacy and newer application could be installed on single machine. Consider your company has developed its own tailor made software on windows XP. You can still run it without any amendment on latest versions of Windows OS using client virtualization. VI. LIMITATIONS OF DESKTOP VIRTUALIZATION Along with above mentioned benefits, there is no desktop virtualization technology without certain trade-offs. For any particular organization considering client virtualization, hosted desktops or their combination, it is necessary to first understand their limitations. Limitation of hosted desktops and client virtualization varies from each other. Virtually hosted desktop face performance issues due to many factors especially when number of end users is increased. This model is not well suited for applications with rich graphics because

clients are served via network. Application with high processing cast and rich graphics could suffer from network band width limitations. Likewise applications using VoIP cannot afford delay in network communication. Responsiveness is a key feature of hosted desktops but in case of large number of end users connected via limited bandwidth network may face a considerable delay in responsiveness. Virtual hosted desktops always run on the risk of single point failure. If network fails or host gets down all connected users will suffer and go out of service. Host machine hardware capability is also vital importance. Sine all computation and storage is dependent upon server machine hardware so it should be good enough regarding storage and processing to accommodate considerable users. Client virtualization has to face its own limitations. Every new virtual machine requires resources on the machine so client machine s hardware should good enough to accommodate multiple virtual machines. Virtual Machines always face a performance issues due to the fact scheduling within scheduling. Whole virtual machine runs as a process with in a host operating system. Applications are first scheduled by virtual OS, which is in turn again scheduled by host OS being as a process. That is the basic reason of slower performance of client virtual machines. So on consider the system structure UML linux, a type II VMM, with two separate host process causes inordinate number of context switches on host to increase the virtualization overhead [14]. To evaluate the performance difference of native computation environment and the virtual computing environment Intel conducted more than 100 performance test on a machine with following specification: o Intel Core 2 Duo T7300 (2 Ghz) Processor o 2 GB RAM o 80 GB, 5000 rpm Hard Disk o Intel Mobile 965 chipset o Intel 82566 Gigabit Ethernet o Intel 4965 AG Wifi o Windows XP Operating System From the test results it is clear that virtual computing environment is about 40-50% slower than native computing environment [13]. VII. CHALLENGES & BARRIERS AGAINST VIRTUALIZATION IT companies are gradually switches towards virtualization and are very clear in challenges to implementation of virtualization. More than 50% IT professional consider deployment cast as a major barrier against the implementation of the desktop virtualization in their organizations. Likewise choosing right solution and right vendor are other leading issues. In a survey conducted by Intel in 2011, nearly 30% respondents are having a problem in choosing a appropriate solution and vendor [15]. Another interesting fact about the IT professional using desktop virtualization that, they are still in evaluation process. Any here is the result of Intel survey regarding barriers in implementing desktop virtualization. Fig. 14. Results of performance Test Fig. 15. Barriers against virtualization

VIII. DESKTOP VIRTUALIZATION CASE STUDY (PUNJAB IT LABS PROJECT) Punjab IT Labs project is the biggest working example of desktop virtualization in the region. Government of Punjab taken a biggest IT initiative to establish IT labs in 4286 high schools of the province in 2008 with the total cost of Rs. 4172 millions [15]. Formally 5155 IT lab were already functional in different high schools of the Punjab with 16 (1 Server + 15 Desktop PCs) per Lab. The Hardware specification of these Labs was designed by the Pakistan Computer beareu, Ministry of Information Technology Islamabad. Before the launching the mega project for 4280 Labs it was decided to review the hardware specification the new labs according to the use context of these labs in educational institutions. Current energy and financial crises of the country were other to key factors to consider. So a decision was taken to switch towards the desktop virtualization technology to minimize the cost. Initiative was taken that, in addition to servers and desktops, thin client computing was being used to maximize the number of terminals in labs. In this regard, ncomputing Technology which offers features specific to education sector was being used. This innovative combination of thin and thick client computing saved millions of rupees regarding hardware, software licensing, power consumption. Instead of 16 (1 Server + 15 Desktops) machines each lab is equipped with just 4 (1 server + 3 desktops) machines and 12 thin clients to accommodate 16 users. H/W Cost Comparison of Lab with 16 terminals Item Core i5 PC KeyBoar d, Mouse, LCD M300 ThinClie nts WinServe r 2012 Licence* CAL Licence* PCs Without ncomputing 65000x16=10,40,0 00 13000x16=2,80,00 0 Nil 17,000x16=2,72,0 00 Nil Total 15,92,000 * S/W License prices from Ora-Tech Pakistan Fig. 16. Cost comparison of ncomputing With ncomputing 65000x4=2,60,0 00 13000x16=2,80, 000 13,000x12=1,56,000 17,000x4=68,00 0 12x4,000=48,00 0 8,12,000 From above comparison it is the clear that desktop virtualization could reduce about 50% hardware cost. There may be even a more affordable solution; you can connect 15 thin clients to a single Core i7 machine with 16 GB RAM, to minimize the hardware cost by compromising the performance. In Punjab IT Labs project, ncomputing is the technology partner. It provides both hardware and software solutions for desktop virtualization. ncomputing provides a vast range of products. ncomputing virtualization solutions include the X, N, L and M series thin clients which are powered by Vspace Server software running on any Microsoft Windows Server OS on host machine[16]. For detailed specification and solution visit www.ncomputing.com Fig. 17. M300 Thin Clients Architecture IX. CONCLUSION Throughout the paper we addressed each and every aspect of the desktop virtualization like virtualization models, benefits and limitations. From our discussion one thing is crystal clear that desktop virtualization is a cost friendly but it is not efficient in performance. There are performance issues in the presence of applications with rich graphics and videos. All the virtualization solutions are scenario based. No single solution is up to the mark for dynamically changing requirements of the organizations that is why companies are adopting virtualization partially as gradually. There is strongly needed to identify the areas where desktop virtualization could be implemented successfully. Education sector is the one of them where, there is no need of extensive processing. Students just use virtual desktops for word processing, spread sheet analysis and web browsing only.

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