Upgrade path: Virtual Desktop Infrastructure vs. Terminal Server vs. Fat Clients

Hi experts

I would appreciate your thoughts about the possible upgrade paths for one of my client's infrastructure.

1. Redundancy and manageability of servers have to be improved
2. Update from Windows XP to Windows 7 and from Office 2000 to Office 2010. About 10-15 workstations do not reach the minimum requirements for Windows 7/Office 2010.
3. Reduce time for supporting workstation installations

Solution to problem 1 is a SAN and an upgrade to the latest VMWare-Version, which the customer is willing to invest in.

For problems 2 and 3, I see three possible paths:
1. Upgrade the workstations or buy new ones and continue working with fat clients. Implement a software distribution solution.
2. Freeze XP on the workstations and use them as ('thin') clients for a terminal server solution (TS). (Microsoft / Citrix)
3. Freeze XP on the workstations and use them as ('thin') clients for a virtual desktop infrastructure (VDI). (VMWare / Citrix)

Now for my questions:
Upgrade path 1 is obvious, but I guess one of the other two might be the better choice.
a) Will it be possible (without impairing the user experience) to run Windows 7 from a TS or VDI on a workstation, which itself does not meet the Windows 7-requirements?
b) What are the pro's and con's of a TS-solution vs. a VDI solution? What should I consider for this client's requirements? (The client will not grow very much over the next few years.)
c) Is there a difference of the user experience between a TS-solution and a VDI solution?
d) Is there a difference of the amount of installation work needed to setup a TS-solution vs. a VDI solution?
e) Is there a difference of the amount of administration work needed to run a TS-solution vs. a VDI solution?
f) How would a TS or VDI solution support notebook users on the road without internet access?

I hope, these are not too many questions for one single experts-exchange topic. ;-)



The existing infrastructure is the following:

25 Workstations (Desktops and Notebooks)
- Windows XP Pro, latest SP and patches
- Microsoft Office 2000
- Microsoft Outlook 2003
- Adobe Acrobat 8
- Document Management Software accessing small (300 MB) SQL database
- Internet Explorer / Mozilla Firefox
- some small, non business critical applications

2 identical physical servers (HP DL380 G5, 2x Xeon 1.86GHz, 10GB RAM, RAID1 for ESX, RAID5 for Virtual Servers)
- VMWare ESX 3.5
- 4 productive virtual servers running Windows Server 2003 R2 Standard Edition 32bit, latest SP and patches
 - Domain controller 1 / file server / print server
 - Domain controller 2 / backup server
 - SQL-server
 - Terminal server (maximum 5 concurrent users so far)

Exchange Server hosted at external provider (no internal Exchange Server)

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a) You might see some issues with XenDesktop (Citrix's VDI) and HDX with really low end workstations.  HDX offloads some of the processing to the client, so in theory that could be an issue.  Overall, though, you should experience no issue.

b) Neither approach is wrong and in truth you may find yourself doing a mix of both as Citrix recommends.  For example, we deliver our desktops with some of our standard applications already installed.  Other applications are delivered via XenApp to those VDI images.  A few of the key selling points for Citrix's XenDesktop were:
1. Using Provisioning Services I can delivery a multitude of VDI VMs from a single Golden Image, so now I just need to update one Golden Image when I need to update an application or the OS.
2. With a non-volatile VM, any changes the user makes (install/update application, malware, etc) are lost upon logoff.  User specific settings are still stored in their roaming profile.
3. Streaming to a VM in a centralized datacenter makes XenDesktop VDI a viable WAN technology.
4. Improved application compatibility.
5. Elimination of nearly every printer/driver issue.
6. Each user has their own "sandbox," so you can give users elevated privileges to a VM without that impacting others.
7. A single Golden Image allows greater agility for performing updates and rolling back those updates.  You can also easily insert a test OS, such as when you need to test moving from XP to 7.
8. Touchy/Feely: users are use to XP, Vista and 7.

c) Our experience is that VDI runs better, especially with multimedia.

d and e) Citrix tries to sell XenDesktop as being easier to deal with than XenApp.  Don't buy in to that.  Our VDI solution utilizes XenServer, Provisioning Services, XenDesktop and XenApp.  So you really need to know all of those solutions well to implement Citrix's VDI.  For their part, Citrix has a nice walk-through in their admin guide on how to set up a complete XenDesktop solution, so it really isn't difficult, though it IS more work than a standard TS/XenApp environment.  In my opinion.

VDI also doesn't offer the same user density per server as a TS/XenApp environment.  For example, suppose I have a server with eight core and 32 GB RAM.  I can run perhaps 25-30 VDI VMs on this server.  On the other hand if I used strictly TS/XenApp, then I could install a hypervisor on that server and run four TS VMs allowing maybe 120-150 users.

f) They wouldn't.  You would need Internet access to connect to either from a remote location.  

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Cláudio RodriguesFounder and CEOCommented:
It all gets down to what you want/need.
Technology wise VDI is still in its infancy and suffers from several problems not to mention in order to have a solution that addresses all VDI's shortcomings you will be dealing with products from several vendors (i.e. XenDesktop from Citrix, Virtualization from VMWare, OS from Microsoft, Storage/Application layering from Atlantis/MokaFive/anyone else and so on). This means when a problem happens fingerpointing will occur. No one will say 'yes it is my problem'. They will start pointing at the other vendor and you the customer, suffers.
TS on the other hand is a mature technology with several years on its back. All Fortune 100 companies do use it. There are well known, stable environments with 50,000 to 100,000 concurrent users. Again, proven and tested technology.
VDI is way more complex than TS for sure. TS is simply a component you can enable on 2003/2008 and you are ready to load the apps. VDI requires creating gold/master images, deciding how you will deal with the deltas/differences for each user, fine tuning your VM infrastructure (i.e. no more than 5-6 VMs per LUN), fine tuning I/O (for maximum IOPS) and so on. Something the average person/admin cannot do for sure.
As of today with both Windows Server 2008 R2 and Citrix XenApp 5.0 FP2, multimedia is as good on TS as it is on VDI. Scalability on TS beats VDI hands down, probably by a 10X factor. Cost per user, thanks to scalability, is MUCH lower on TS than on VDI.
Both, as of today, have no way to deal with offline users (well VDI is trying to get there using Type 1 hypervisors on the client side but his requires very specific hardware AND it is still in experimental mode). Your best option for offline users is to use Application Virtualization like Microsoft App-V or Citrix Streamed Apps (App-V is free with 2008 R2 TS CALs).
As of today, with the current state of technology I would only use VDI for very specific needs (i.e. to handle an application that does NOT work at all on TS - note these are very rare these days).
Otherwise I would stick to TS. Performance/Scalability/Costs cannot be beaten at this stage.
What the future holds I do not know but again, for today, TS wins hands down.

Cláudio Rodrigues
Citrix CTP
Fingerpointing is indeed a concern.  We went with a complete Citrix solution (XenServer, XenDesktop, XenApp, etc) to alleviate much of that.  Still, there is a bit, though.  One issue we ran in to was a XenServer technician telling us to do things according to certain XenServer best practices, though those best practices would break Provisioning Services.
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Cláudio RodriguesFounder and CEOCommented:
Sometimes people think I do not like VDI at all. That is not the case. I do see a benefit for using it but only in certain cases. Several things must happen with VDI to turn it into some mass used technology. As of today VDI is a niche in an already niche market, the TS one.
Until VDI can indeed become a physical desktop replacement, it will always be that, a niche. And to become a real replacement, several things must happen, some 100% up to Microsoft.
If we look at Windows (the OS), it was never meant to be used the way VDI uses it (relying a lot on layering - the only real way to make VDI work/scale) and that is just one item on the list. Another example, Windows was tuned on the I/O front end to use real, physical disks. When you move this to a virtual environment, the landscape changes completely.
Do not get me wrong. VDI will get there for sure. Is it there today? No. Will it be there next year? No. More time is needed.
Read my blog at http://www.wtslabs.com/blog. Tons of great information on VDI, the whole user installed apps debate, Bring Your Own PC idea (BYOPC) and so on. Worth reading and will give you a great picture of the current landscape in the SBC industry.

Cláudio Rodrigues
Citrix CTP
daniel-hAuthor Commented:
Thanks, Michael and Claudio for sharing your valuable experience. Given that I don't want to experiment with my client's infrastructure, but suggest a stable, reliable and cost-efficient solution, TS with Citrix support would probably be the better way to go according to your input.  
Do you have experience in running Windows 7 from a TS on a workstation, which itself does not meet the Windows 7-requirements (graphics requirements not met, RAM requirements not met)? (OK, it certainly would not be a problem adding a cheap graphics card or more RAM to an old workstation. Anyhow - if not needed, why should I spend money to upgrade?)  BTW - I'll certainly read your blog - but alas, now it'ss too late in Europe, so good night ;-)

You won't be able to run Windows 7 as a TS solution.  TS/XenApp is server based, so the OS your end users will experience is 2000, 2003 or 2008.  With that said, TS/XenApp offloads the processing and RAM requirements to the server, so the end client just experiences screen shots and input (mouse/keyboard) feedback.  The end user workstation does not need to be powerful at all due to this and doesn't even need to be Windows based.  
Cláudio RodriguesFounder and CEOCommented:
I do not think he means literally running Windows 7 on TS. I assume he is aware the TS would be running an OS like Windows Server 2008 R2. That said, you can enable several options on 2008 R2 that will make the 'Desktop' for the users look identical to a Windows 7 one, with Aero glass support included.

Any machine will work connecting to a 2008 R2 hosted environment and if you are on XP SP3 and the latest RDP client you will get almost Windows 7 like experience (without Aero as XP does not support it). But things like multimedia redirection will work for sure. IMHO it is good enough the way you will see it without upgrading anything and should work great. But again, as on any solution you should test for yourself.

Cláudio Rodrigues
Citrix CTP
daniel-hAuthor Commented:
Of course I should have written 'Windows 7-like'. I appreciate your time and your input and will most certainly go for a TS solution according to your comments. Thanks again to both of you for your answers to my questions.

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