VDI in some detail

Introduction

In the past few years there has been and continues to be a lot industry buzz around virtualization. At this point most are familiar with the concept of server virtualization and consolidation using VMware vSphere 4, Microsoft Hyper-V or XEN based hypervisors. Additionally, many have been successful using application virtualization and streaming technologies like Microsoft App-V or VMware ThinApp to address application compatibility, version control and deployment issues. 

Enterprise Desktop Virtualization allows organizations to employ small, secure thin clients on the user's desktop and then link them to their own virtual desktop machines residing on centrally managed servers.

VDI is a designation for the hosting and virtualization of a individual Client OS like Windows XP Professional, Windows Vista, Windows 7 or Linux on a hypervisor. The intent is to be able to deploy, secure and manage enterprise desktops in the data center.

For those used to managing server based computing environments, consisting of Windows Terminal Servers and Citrix, managing VDI is a very similar task. The difference is that instead of managing numerous centralized, multi-user server operating systems, one would be managing potentially hundreds, or thousands of centralized, virtualized single user operating systems.

Architectural Overview

VDI is not one product, but rather a technology consisting of five separate components:

• Thin Client Computer
  
  Most leading thin client manufacturers are coming out with new devices geared toward VDI. The only differences between these devices and their standard thin client device offerings is one or more built-in 3rd Party Connection Brokers. Some are also offering local graphics acceleration where MPEG1 & MPEG2 are rendered locally using the thin client’s display adapter, while others are offering VOIP Soft Phone Support. Although any computer could act as a thin client device, true thin client terminal are more often the choice for VDI and companies don’t want to continue to manage the client OS.
  
  
• 3rd Party Connection Broker
  
  The Connection Broker is the brains of the architecture that determines which Remote Desktop Host a user is assigned or connected to. The broker is often a full-blown management product allowing for the automatic deployment and provisioning of Remote Desktop Hosts. There are several vendors offering connection brokers. Examples are VMware View and Citrix XenDesktop.
  
  
• Virtualized Remote Desktop Host
  
  Single User Windows or Linux Client OS Hosts, Virtualized on VMware. Client computers connect to these hosts via presentation protocols such as Microsoft RDP, Citrix ICA, PCOIPor NX.
  
  
• Virtualisation Layer
  
  The virtualisation hypervisor allows for hosting of hardware agnostic Virtual Machines. In the case of VDI, the hypervisor is used to host many Virtual Machines of the Remote Desktop Host Operating Systems. Examples of virtualisation software are VMware vSphere 4, Microsoft Hyper-V and Citrix XenServer.
  
  
• Centralised Management
  
  Software component for managing hypervisor systems and libraries of Virtual Machines. Examples are VMware vCenter 4, Citrix XenCenter and Microsoft Hyper-V manager.

   

  Usage Scenarios

  There are many advantages and some disadvantages to any VDI Solution, but some common usage scenarios are:
  
  Enterprise Desktop Consolidation – many organizations struggle with management of their client computers. Tasks like procurement of desktop computer hardware, deploying or patching desktop operating systems, updating antivirus signature, securing data, and desktop support become more and more challenging as the size of an organization grows, and the disbursement of employees across multiple locations increases. Replacing all or a bulk of an organization’s computer workstations with expendable thin client terminals and managing the client OS and applications in a centralized location is something most CIOs would love to be able to do.
  
  Remote Developer Support – as companies have outsourced all or some of their development efforts, some problems have arisen. How does one provide a remote application developer with a powerful, secure working environment, while protecting the parent organization’s source code and intellectual property. VDI addresses these issues by providing a remote developer with one or a group of virtual machines that can be used, rebooted, destroyed and easily rebuilt. Since the working environment is contained in the corporate data center, source code remains in the hands of the owners.

Advantages of VDI

• Reduced cost in purchasing desktop computers, as thin clients often last two to three times longer than a desktop computer
• Centralized Client OS Management
• Rapid Client Deployment
• Reduction in desktop support costs
• Reduction in electricity costs, as thin client computers use only a fraction of amount of energy that is used by a desktop computer. 
• Improved Data Security
• Secure Remote Access, as most connection brokers offer an SSL VPN Component and Web Portal
• Compliance with HIPAA and Sarbanes Oxley (SOX)
• Fewer Application Compatibility Problems than with Terminal Server and Citrix, as users have their own, single user OS.

Disadvantages of VDI

• Requires Enterprise Class Server Hardware and Storage Area Network
• For VMs permanently assigned to specific users, these machines need to be patched just like a physical client computer.
• Requires IT Staff skilled with virtualisation software and terminal server.