Just did some installations of the Virtual Desktop Infrastructure solutions from Citrix and VMware and I wanted to a "versus" article to have a comparison between the two. There are some other ones there like Provision Networks (now Quest) and LeoStream, but with two large vendors like Citrix and VMware who also have direct access to the developers and code for the underlying products (like Citrix's XenApp, XenServer, Provisioning Server, and VMware's  ESX, Virtual Center, Thinstall), I just have to be realistic about the players in this space. I can't look at every solution out there and put it through its paces, so I have to work with what I have can easily access. Right now, that is Citrix's and VMware's solutions for VDI. Also I spent about 1 day reviewing the solutions, and then I wrote this article. As I spend more time with the solutions, I'll deliver more insight, but I wanted to share what I have seen so far. If I can get access to Provision Networks or Leostream anytime soon, I will update the article. Microsoft also recently bought something in this space (http://www.pcmag.com/article2/0,2817,2275524,00.asp) but there needs to be more information before we can really see what this technology does.

Virtual Desktop Concept
A virtual desktop is a desktop OS that is running virtually on server class hardware along with other virtualized desktops. In a Server Based Computing (SBC) model, you have 1 OS shared for multiple users, with a VDI model, you each have your own OS to do whatever the user wants. Now that the desktop OS is virtualized, there are some great advantages. Information security is kept within the data center. Desktop performance may be increased as the OS is in the data center with the back end applications reside. You are utilizing the latest and greatest server class hardware. Remotely access your desktop from any location. Maintenance of physical desktops is greatly decreased. 

However VDI isn't without its downfalls. If you don't have a good way to deploy applications into the desktop or patch/maintain applications and the OS itself, then VDI doesn't really solve that. Since it is a presentation layer remote display, any network outage or problems will result in uses not having access to their desktop and applications. (At least in most Server Based Computing models, their desktop OS and locally installed applications would still work when there was a network issue). Though there are some capabilities for USB devices, not all peripheral devices will be supported. VDI has really hit the market because standard desktop deployments are too costly and server based computing models (like Citrix XenApp or Microsoft Terminal Server) hasn't address all the user needs for customization, but VDI isn't cheap either. You will be buying server class hardware and storage to give a desktop that usually runs on cheap HW and cheap storage. If are planning on delivering lots of desktops and want save to save disk storage costs, you may need to acquire large to enterprise class storage de-duplication. And as always allowing for user customization (Private Desktops), the risk of something going greatly increases and users can attempt to install/uninstall applications that may jeaperdize the system.

So how did we end up here?
Standard desktop deployments have become too costly to maintain and control. All the application and operating system updates. Then because users have some form of control of their own system, they install an application or run some update that messes up their PC requiring the help desk to resolve. Then some admins remember the "good old days of mainframes" and in comes the next wave of computing: Server Based Computing.

While Server Based Computing (SBC) solutions like Citrix XenApp and Microsoft Terminal Server have solved many application deployment issues, there have always been concerns about delivering a full desktop experience to users. Users are used to having full control and access to everything they can do on their home PC. In a SBC world, users may not be able to plug-in random devices, or set desktop backgrounds or install their own applications. Users have very little to no control in a SBC world.

Because of lack of control, more computer savvy users and evolving computing requirements, SBC has had a hard time keeping up with all the demands a more knowledgeable user demands. Not that VDI fixes every one of the situations because it really only has come to market within the past year, but it can address situations for a lot of clients. So let's look at two of the solutions now.

Citrix XenDesktop Brief Description
Citrix XenDesktop is still currently in Beta. It is expected in Q2 of this year. No pricing has been announced yet. There will be 3 different flavors based on client requirements. The naming scheme is completed, but there will probably be Standard, Enterprise and Platinum edition. Platinum Edition will come with some remote support tools, a remote access plus VPN solution, a provisioning solution to lower the cost of disk storage and some WAN optimization clients.
XenDesktop will provide access to a virtualized desktop running on Citrix XenServer or VMware ESX. The connection protocol will be via Citrix's ICA. So whatever devices and capabilities you have today with the ICA protocol on XenApp, you can expect them on XenDesktop. These desktops can be shared or private desktops. Shared desktops can have their disk space requirements greatly reduced. Citrix's ICA protocol has been the standard for remote display protocol since was first developed in the 1990s but only recently has it made it any in roads to highly graphical based applications.  

VMware Virtual Desktop Manager (VDM) Brief Description
VDM was released early in Q1 of 2008. It is priced in two ways.

• If you have a VI (Virtual Infrastructure) already deployed with ESX and VirtualCenter, then you just need the VDM connection licenses which are about $50 per desktop plus Subscription and Support.
• If you do not have any VI or are planning to deploy a VI that is separate from your existing VI AND will be less than 3 ESX Hosts, you can buy VDI Starter Kits and VDI Bundles which is about $150 per desktop plus Subscription and Support.
  Note: If you don't have any VI and expect to need more than 3 ESX Hosts, then you will need to go with the top option AND buy the Virtual Infrastructure (ESX for as many servers as you need and VirtualCenter).

VDM is primarily a connection broker that allows a user to login, possibly be given a choice of desktops and have their desktop remotely displayed to them. That is it. For patching the OSes, VMware's solution is that you already have in place from a 3rd party company or that you implement VI 3.5 with Update Manager (requires VirtualCenter). For application deployment, VMware's solution is that you already have a solution in place or that you acquire their Thinstall technology (not part of VDM at this time). Disk storage can be a major cost in VDI and so VMware is highly recommending SAN solutions that can perform de-dup (De-duplication of data on the storage device since much of the OSes will be similar).

Installation: Citrix is a disadvantage right now as the installer for their product I'm testing with is currently in beta, but it is all I have access to at this time. Citrix's beta doesn't have a single installer, but rather multiple installers that must be deployed in a certain sequence. Citrix also seems to require you to use Citrix Provisioning Server. So even if you didn't want to deploy it, you couldn't keep going. I know this may change later, but beta code is all I have. VMware's installer was much easier and within just a few minutes with very minimal reading I was up and running. I like to test each technology and installer once with a cursory look at the admin guide. I fully really the admin guide before any deployment, but I look to know what areas they address during the installer versus what they address in pre-config or post-config. VMware wins.

Configuration: VMware's configuration is also very simple. Create a VM with a desktop OS in VirtualCenter, install the VMware Tools and VDM Agent, convert to a template, add VirtualCenter into VDM and away you go. From there you can decide on the minimum and maximum number of desktops always available for use, and assigning templates to users or groups of users. Users can either connect via a preinstalled VDM Client or via the ActiveX Control on the connection broker web site. Citrix's solution is a little more complex and requires multiple interfaces to get setup. One interface is for assigning a desktop. Another interface for creating the desktops. Another interface for creating the vDisk (what Provisioning Server calls its disk files). The steps to configure are about the same (create VM, install tools, make it a template, add into interface, assign to users), but due to multiple interfaces and having to know each different interface can be confusing to a new admin. VMware wins.
Note: Some may argue that less configuration means less features. Yes, that is true, but I'm addressing that later.

Display Protocol: Basically this is Citrix's ICA vs VMware's RDP. Just google for "ica rdp site:youtube.com" or "xendesktop vmware site:youtube.com" to see some of the videos. ICA blows RDP away. As the application requirements and user requirements grow, the display protocol will become more critical. With Citrix's extensible virtual channel system, not only can Citrix adapt their technology but other 3rd party companies have and wil continue to write products for it. While RDP is serviceable, it is not anywhere near ICA. Additionally, VMware has already written one add on component for Extended USB support to add additionally functionality to RDP which means VMware has identified weaknesses in the RDP protocol and may found more limitations as they continue down this path further. Citrix also has many capabilities with SpeedScreen to speed up Flash, IE, Keyboards, etc. Citrix wins hands down.

Pricing: Citrix is still in beta and has no public pricing so... VMware wins by default for now.

Application Delivery: VMware has only recently purchased Thinstall so some speculation has to come into play here. VMware will assume that you already have an application delivery system to get apps installed or deployed into the virtual desktops (think SoftGrid, Citrix, SMS, Altiris or maybe it is just part of a base template image). If not, then VMware's Thinstall will be a solution they will offer to complement their solution. Thinstall's roadmap has been fully released but I'm sure they are working on a better system to get to the apps/updates to the system and how the applications can interoperate. Until then, Citrix has a solution with XenApp or with Application Streaming technology. Though there might be additional cost for Thinstall or XenApp/App Streaming, Citrix has been delivering applications like this forever. Also since Citrix can deliver Applications only to partners or to many types of devices, they clearly standout. Citrix wins.

Administration: VDM is administered via VirtualCenter and a Web Site. Citrix's solution is administered via mutiple interfaces depending on what you have to do. Citrix will probably have way more options when it goes GA (general availability) since it will probably tie in with their End-point Analysis capabilities, Policies and Rules Engine. So do you like simple is better? or do you like more options and capabilities which means a little more complexity to the interface? I have to give the nod to VMware right now even with less options. It is a lot cleaner right now. VMware wins.  

Features:

• VMware Security Server will allow for remote access to deliver a desktop to the user from outside the corporate firewall. Citrix is planning on the same capability using its Citrix Access Gateway functionality that can also deliver a SSL VPN if necessary. I don't know if a Citrix Secure Gateway equivalent will exist but I doubt it. The Access Gateway user license may cost additional money, but the device itself sure will cost something. This part may be the most interesting since the SSL VPN with Citrix will quickly allow Citrix to add additionally functionality for offline capabilities that VMware tries to deliver with ACE. (Note: VMware ACE is different interface and has different capabilities than VDM)
• High Availability. VMware assumes you have a HW based load balancer to deliver high availability of the access mechanism and services. The desktop OS HA will be delivered with VMware Virtual Infrastructure's HA capability. Not enough citrix info on this yet other than if you use VMware VI3 to deliver the desktop OSes or if you wait until Q2 for the next XenServer.
• Resource utilization. VMware will be using its DRS and Resource Pools to control use of physical resources of the Virtual Infrastructure. If you use VMware VI3 with XenDesktop, you will gain this option, but XenServer does not deliver this at this time (Possibly Q2 or so).
• Citrix's Provisioning Server can really help to decrease SAN storage when using shared desktops. VMware will use a lot of storage no matter which desktop type you choose, unless you happen to have SAN technology that can perform de-duplication.
• Citrix also will be including a Remote Support tool via GoToAssist. That is pretty cool since you will need something to be able to remotely administer PCs and desktops.
• VMware has Update Manager to control Windows Updates (if using ESX 3.5 and VC 2.5). Citrix is assuming you update the base vDisk with all the updates and then perform the deployment. Otherwise you have to use another solution for OS updates.
• Citrix will integrate with its End-point analysis capabilities.
• Citrix's Session Reliability is a great feature to keep desktop connectivity alive during small network outages. Very critical when everything runs through the remote display protocol and any network link outage or slowness will affect the user.
• Citrix EdgeSight (probably bundled with highest version of XenDesktop) will be used to perform application and desktop monitoring for performance and usage.
  No super clear winner. But I'm going to give the slight edge to Citrix right now. I don't know if everyone is going to want pay for HA and DRS for desktops so any advantage VMware has with its hypervisor capabilities may not be necessary. Also the remote access solution from Citrix allows for additional features that will easily integrate with future solutions to deliver offline capabilities.

Wrap-up
Citrix's technology solutions are centered on application deployment is far more robust while VMware is the800 lb server/desktop OS virtualization gorilla in the room. So let's follow the money... Citrix doesn't make money from the OS virtualization, they make money from delivering the app. VMware doesn't make money from application/desktop delivery; they make money from virtualizing the OS. It can be safely assumed, that to gain market share in each other's backyard, they will basically give away what they don't do well on the message of its the complete package that is strategic interest to the client and therefore will make the client pay for what they do well. So beware of this. One company may give away its server virtualization to sell their other product and the other company may give away its application delivery mechanism in the hope of getting its other product sold. Don't buy the cow, when you only need the milk. You might not like what you are "not paying" for.

This is just the beginning of this battle and 1 product isn't even out of beta yet. There are still many things left to be decided. Is VDI the holy grail of desktop computing? Is SBC still a viable solution? Will SBC use go down in favor of VDI or will VDI be niche solution for one-offs (like developers or knowledge workers)? No easy answer right now since each solution has it's own pros and cons... Just like VMware VDM and Citrix XenDesktop each have their pros and cons.

Hopefully this article has given you some insight on the technologies and helps to defuse some of the fear, uncertainty and doubt (FUD) everyone is putting out. So grab some popcorn, and a soda... it's going to be a fun ride.

My Opinion of the VDI Space
Just to give a little background, I've been doing SBC since 1999. I came into Server Virtualization in 2001. They are both great solutions for my clients. I have been being "sold VDI" since 2006 as it being the solution for desktop deployment. I've seen the good and bad of SBC. The bad has always been around user customization and being able to install your own apps and while yes, VDI does allow for that capability... I'd rather treat that as one off than pushing everyone away from SBC to VDI. For power users, developers, applications that require a specific OS or just intensive gaming/learning applications, VDI is a very good model, but I still see that as a business owner I would want the control of the IT systems... not all of my users. Do admin assistants need to install apps? Does the kitty cat screensaver make you work better? Do you have to listen to a CD on the computer or do you have to use company assets for you iPod? I'm not saying SBC is better than VDI, just that the Total Cost of owning an SBC solution is better than VDI. Just like VDI is better to give users access to a customizable environment. Its all about requirements. What do you need now? What do you currently own now? How much is your budget? What are the issues you are trying to resolve now? What do you foresee in the near future of needing? Only questions like these can really determine what you need.