by November 1, 2011 0 comments

AVirtual Desktop Infrastructure, as the name suggests, is not created from a single product, but rather, from a set of products. Therefore, it would vary based on your specific requirements. We’ve already discussed the various cost components in a VDI implementation in a separate article in this story, so here, we’re going to take a more detailed look at the soft side of things-the software that helps you build a hosted desktop infrastructure for your organization. The key contenders for a VDI deployment are VMware, Microsoft, and Citrix.

Before you choose any one, it’s important to ask yourself a few questions like-

  • What sort of investments do I need to make in my server, storage and networking infrastructure to support VDI?This varies significantly in cost depending on the type of VDI solution you want to deploy.
  • Which applications do your users need to run? Will they be supported over VDI? How shall my users experience change in terms of graphics, performance and mobility if they access these apps over VDI?
  • Which VDI technology would be more apt for my needs? Would application streaming be sufficient, or do I need to provide a complete desktop to my users, or is there something else available as well?
  • How secure would the infrastructure be? Do I have to invest more in network security considering that the desktops would be accessed over a LAN or WAN?
  • What sort of skill sets are required to implement and manage my VDI deployment? Would I need to re-deploy my workforce after doing VDI?

The above are just a few questions that you need to ask yourself before going for VDI. There are lots more, and most of them can be answered simply by understanding the various VDI solutions available. Plus of course, a deeper look into what the actual VDI software providers have to offer also helps in gaining a deeper understanding of the subject. We’ve already covered VMware’s View solution for VDI in a separate article, wherein we’ve demonstrated how to implement a server hosted VDI deployment. Here, we’ll also talk about two other key players in this space, viz. Microsoft’s Hyper-V and Citrix XenDesktop. While each has their own specific solutions, they also have a partnership going for specific types of VDI deployments.

Types of VDI solutions

At the broad level, there are two types of VDI solutions—client-side and server hosted. In a client-side VDI, you run the virtualization solution on the local desktop itself and have multiple operating systems running on top of it. Here again, you could run a bare-metal type of VDI, wherein the virtualization layer installs directly on the hardware, or you could run a hosted VDI, where you have an OS already running on the machine, but install the virtualization software as an application, and then set up virtual machines (VMs) on it.

The other type of VDI is server hosted VDI. Here, you could either have a shared or a personal remote desktop. The shared desktop is another name for the age-old thin clients/terminal services technology, so no further explanation is needed. Another term for this is Remote Desktop Services. A personal remote desktop can be made available either as a remote virtual desktop or a remote physical desktop. The former is again in the form of virtual machines that run off a central pool. The hardware resources are allocated to each virtual machine from a shared pool of hardware. So while each user gets his own personal desktop OS, there’s a challenge in terms of running graphics-intensive applications. The latter, remote physical desktop involves running a personal desktop on blade servers in the data center. So each blade runs a single desktop OS and is accessed remotely. Such a setup allows for more graphics and performance intensive work, but at the same time, it also requires more resources and is far more expensive.

Citrix XenDesktop

The VDI offering from Citrix is called XenDesktop, and is available in more editions as compared to the competition. There’s even a free edition available that’s limited to 10 concurrent virtual desktops. Other editions include Standard, Advanced, Enterprise, and Platinum.

The bare minimum components required for doing VDI with Citrix include a Desktop Delivery Controller, XenServer, and Virtual Desktop Agent. The other components that provide additional functionality include Citrix XenApp, Desktop Director, Desktop Studio, Access Gateway, EdgeSite for Virtual Desktops, WAN Scaler, and GoToAssist. Plus of course, Citrix also introduced a new technology called HDX, which provides 3D support. Since there are so many different components, setting up a Citrix-based VDI could be a bit complex. Let’s see what some of its base components are and their functions:

Citrix XenServer: This acts as a hypervisor and provides the platform for virtual machines. It’s the foundation for a Citrix-based VDI deployment, and requires a server with at least one or more 64-bit x86 CPUs that are 2 GHz or faster and are multi-core. The server CPUs must have built-in hardware virtualization technologies, which are pretty standard with most server CPUs from Intel and AMD today. It requires at least 2 GB RAM and 60 GB locally attached storage.

Desktop Delivery Controller: It’s responsible for authenticating users and managing the broker connection amongst users and their virtual desktops. It also manages the initiation and termination of virtual desktop based on configuration. To setup the Controller, you need a server with at least Windows Server 2008 (Standard, Enterprise, or R2), MS IIS 7.0 upwards, and ASP.NET 2.0 for the web interface and Desktop Director. Plus, it requires other components like Visual J# 2.0, Visual C++ 2008 with SP1, and Windows Power Shell Version 2.0. For the database, it supports both 32-bit and 64-bit versions of MS SQL Server 2008 R2, MS SQL Server 2008 R2 Express edition and MS SQL Server 2008 with SP1 or later.

Virtual Desktop Agent: This is installed on the virtual desktop to enable connection amongst the virtual desktop and user devices. Virtual machines using Virtual Desktop Agent should be run on Win XP (32 and 64-bit), Vista (32-bit or 64-bit with SP2), or 7 (32-bit or 64-bit).

Desktop Director: This component helps the IT department to configure, monitor and maintain the deployment. They can also interact with the user using Microsoft Remote Assistance. It can be installed on the same server on which Controller is installed, so the same server pre-requisites apply here as well. Plus, for the web-based interface, you must have IE 7.0 or 8.0, Mozilla Firefox 3.5 or above, Apple Safari 4 (for Mac) and Adobe Flash Player 9.

Desktop Studio: This component helps manage the XenDesktop deployment like creating virtual desktops and assigning users to them. This can be installed on most Windows desktops, including Win XP/Vista/7 and even on Windows Server 2008.

VDI Solutions Compared


Citrix XenDesktop

Microsoft Hyper-V

VMware View

Guest OS’s supported for clients

Microsoft Windows 7, 32-bit Y Y Y
Microsoft Windows 7, 64-bit N Y Y
Microsoft Windows Vista, 32-bit Y Y Y
Microsoft Windows Vista, 64-bit Y Y N
Microsoft Windows XP, 32-bit Y Y Y
Hypervisors supported Citrix XenServer 5.x Microsoft Hyper-V; Microsoft Hyper-V R2 SP1 VMware VI 3.5; VMware vSphere 4.0/4.1/5
Management Software Citrix XenCenter Microsoft SCVMM VMWare Virtual Center
Free/Trial Version Availability Express Edition that supports up to 10 concurrent virtual desktops available 180-day evaluation of Windows Server 2008 R2 with SP1 60-days trial of VMware View Premier with license for 100 simultaneous client sessions
Mobile Platforms/Devices Supports Android, iOS Android, iOS Android, iPad
Live Migration of Virtual Machines XenMotion Y vMotion
Graphics support (Protocol or technology) HDX RemoteFX PCoIP
Editions Citrix XenDesktop Microsoft Hyper-V VMware View

Option 1

Express Edition: Comprises of Desktop Delivery Controller that supports up to 10 concurrent virtual deskops; XenServer Express that limits the number of virtual machines per system to 4. VDI Standard Suite: Hyper-V Server 2008 R2, Mgmt Suite comprising of System Center Virtual Machine Manager 2008 R2, System Center Operations Manager 2007 R2, and System Center Configuration Manager 2007 R2; MS Desktop Optimization Pack; Windows Server 2008 R2 Remote Desktop Services VMware View Enterprise: vSphere Desktop 5, vCenter Standard for Desktop 5, View Manager 5, View Client;
Option 2 Standard Edition: Desktop Delivery Controller Full Edition, XenServer Standard Edition, and an Access Gateway that’s licensed for use with XenDesktop only. VDI Premium Suite: All features from the Standard Suite plus additional user rights for Remote Desktop Services, and App-V for RDS VMware View Premier: All components from Enterprise Edition plus View Persona Mgmt, View Composer, Client with Local Mode, vShield Endpoint, ThinApp 4.6 Packager and Client, with VMware Workstation 8
Option 3 Advanced Edition: Desktop Deliver Controller, XenServer Enterprise, Access Gateway that’s licensed for use with XenDesktop only, Includes provisioning capabilities for desktops, and User Profiles Manager NA NA
Option 4 Enterprise Edition: All features from the Advanced Edition plus XenApp for Virtual Desktops Enterprise edition licensed for use with XenDesktop only. NA NA
Option 5 Platinum Edition: All features of the Enterprise edition plus full Access Gateway, EdgeSight for Virtual Desktops, WANScaler, and GoToAssist. NA NA

Machine Creation Services: This is actually a collection of services to replicate the desktop image and manage storage. It is supported by Citrix XenServer 5.6 Standard and Enterprise editions, VMware vSphere 4.1 (ESX 4.1 and vCenter 4.1, and ESXi 4.1 and vCenter 4.1), vSphere 4 (with ESX 4.x), and Microsoft System Center Virtual Machine Manager 2008 R2 (with Windows Server 2008 R2 Hyper-V).

Microsoft VDI

After launching its Windows Server 2008 R2, Microsoft renamed its Terminal Services feature to Remote Desktop Services or RDS. It also introduced roles like Remote Desktop Virtualization Host. When you integrate this with Hyper-V, you can create a virtual desktop pool and different user accounts can be mapped with virtual desktops to this pool. This can be done with the help of the Active Directory Domain Service.

Another addition to Windows Server 2008 R2 with SP1 is RemoteFX. This facility offers a rich user experience for VDI by allowing 3D applications, and high-definition video to run smoothly.

Like VMware, Microsoft also has two VDI suite editions. These are the MS VDI Suite Standard and VDI Premium Suite. The latter offers all components of the former, plus additional user rights and App-V for RDS.

To setup VDI with Microsoft, there are different Windows Server 2008 roles that need to be added. These include roles for Remote Desktop Virtualization, Remote Desktop Session Host, Remote Desktop Connection Broker, Remote Desktop Web Access, and Remote Desktop Gateway. Let’s understand these in a little more detail:

Remote Desktop Virtualization: As discussed earlier, Windows 2008 server introduced this role. It allows an administrator to create virtual machines which can later be assigned to different users. Its virtual host agent service manages the connection with virtual machine on a user’s request.

Remote Desktop Session Host (RDSH): It hosts the Windows-based remote applications or desktops for the user. A user can access RDSH server using intranet or Internet using RemoteApp or Remote Desktop Connection. A user can independently work on an application, shared by others, without being affected, since every user has his own session.

Remote Desktop connection Broker: It allows a user to access the virtual desktop and also connect with resources available. It also prevents the user from being connected to a different session on disconnection.

Remote Desktop Web Access: It allows a user to connect to a remote desktop on a virtual machine that is running on Remote Desktop Virtualization host. A user can access these applications through a web browser or create shortcuts in his start menu. However, this is applicable only to systems running Windows 7.

Remote Desktop Gateway: It allows remote users to connect to a private connection using the Remote Desktop Protocol (RDP) over https, by establishing a secure and encrypted connection.

VMware View

Lastly, we come to VMware View. We’ve already explained in detail a sample deployment of VDI using VMware with all components, so we’ll not delve into too much detail here. It suffices to say that like MS, VMware VDI also comes in two editions: VMware View Enterprise and VMware View Premier. For graphics support, VMware uses a technology called PC-over-IP, or PCoIP. You can download a 60-day trial version of VMware View Premier that supports up to 100 simultaneous sessions.

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