Should Citrix XenApp be used to virtualize apps for XenDesktop VDI?

Posted by Jeff Pitsch on Nov 21, 2016

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As a Citrix Technology Professional, I've worked with hundreds of Citrix customers who are starting to implement VDI with Citrix XenDesktop. Most have been using Citrix XenApp for years to publish a handful of core applications to physical PCs. Surprisingly, some are thinking they'll just continue using XenApp to publish these core apps to XenDesktop virtual desktops, even though they are implementing Unidesk to streamline application and image management for the new VDI environments.

When I explain the cost, performance, managability, and network ramifications of doing this, and the different options Unidesk now gives them for both XenApp and XenDesktop, they say, "Of course, why didn't I realize that?" It's not their fault - nobody has explained it to them! That's what I'll try to do in this blog.

Ramifications of Using XenApp to Publish Apps to XenDesktop VDI

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Many IT organizations live by the saying "If it ain't broke, don't fix it." That seems like it should apply to XenApp. If you already have XenApp silos that are happily publishing apps to your physical desktops, and you're able to centrally manage the apps once without having to update every machine, why not keep doing the same thing with your virtual desktops? Here's why that's not a great idea:

  1. Double the infrastructure cost. You now have to purchase and maintain two sets of data center servers and storage - one for hosting the XenDesktop virtual desktops and another for hosting the XenApp applications.
  2. Double hop network connection. Users have to connect twice across the network - once to access their virtual desktops and a second time to access their applications. While Citrix HDX is a highly optimized protocol, this is still slower than connecting locally to apps that are already delivered with the virtual desktop.
  3. Different IT skill sets. XenApp and XenDesktop require very different skill sets. Both demand Level 2/3 administrators who cost more and are harder to replace than junior administrators.
  4. Increased network costs. Pulling bits across the network twice - once for desktops and again for apps - adds latency. To counter the performance impact on users, you may require costly network upgrades, load balancers, and caching solutions.
  5. The issue of the remaining apps. Even if you use XenApp to continue publishing the core apps, what about the many more departmental and one-off apps that are currently installed on PCs by agent-based software distribution tools or built into the PC images? These apps still need to be delivered in VDI.

Use Unidesk and Scale XenDesktop VDI Faster for Less Cost

unidesk+xendesktop.pngUsing Unidesk to package and deliver all the apps for XenDesktop VDI will reduce costs, provide a better user experience, and enable you to scale XenDesktop faster. Here's a real example.

This week I met with a big U.S. technical university. The central IT organization is running a project to consolidate the small VDI silos that have been popping up in various departments. Their goal is to offer a single managed VDI service through XenDesktop that all of the departments will leverage.

Today, XenApp is used to publish the 6-10 common applications that are used across the small VDI deployments as well as the much larger installed base of physical PCs. Central IT was thinking of keeping XenApp in place for those core apps and using Unidesk to package and deliver the 100+ other apps specific to each department.

Here's why they are now planning to use Unidesk to deliver all apps in the new XenDesktop VDI environment:

  1. Capital cost savings - XenApp infrastructure reuse. They can repurpose the servers and flash-optimized storage now being used in the XenApp environment for the XenDesktop VDI deployment. This will reduce the overall cost of VDI.
  2. Operational cost savings - app packaging efficiency. All apps can be packaged the same way with Unidesk in a lot less time, using lower cost Tier 1 IT resources.
  3. Operational cost savings - image management efficiency. Windows operating system updates can be made once each month to the shared Unidesk OS layer, instead of multiple times to XenApp Windows Server and XenDesktop Windows 7 or 10 images.
  4. Capital cost savings - network. By delivering apps as if they are locally installed on each desktop, double hop network connections and the need to upgrade network infrastructure are avoided.

Use Unidesk and Just Stick with XenApp for Even Lower Cost Desktops

unidesk+xenapp.pngJust when the university thought XenDesktop for desktop virtualization and Unidesk for application management was the best idea, I gave them another option: why not use XenApp shared hosted desktops personalized with Unidesk Elastic Layers? Then they could leverage the greater user density and lower infrastructure requirements of XenApp to deliver desktops at lower cost than XenDesktop VDI. Unidesk Elastic Layering would attach the apps that each student, faculty, and staff user needed at login based on AD entitlements to provide a personal, VDI-like user experience.

This blew their mind. They never considered XenApp because they didn't think it was possible to customize shared desktops with unique apps. Of course, the usual XenApp vs XenDesktop decision criteria still apply. In the university's case, the idea was quickly dismissed because they have too many apps that will not run properly on the multi-user Windows Server OS. They also have student labs with locally attached probes, scanners, and other devices that require the superior USB pass-through capabilities of XenDesktop VDI. But XenApp desktops personalized by Unidesk could be a viable option for other organizations who don't have these requirements.

So, keeping XenApp around to publish apps to XenDesktop VDI probably doesn't make a lot of sense. But these 3 options do:

  1. Use Unidesk to package and deliver all apps to go "all in" on XenDesktop VDI.
  2. Use Unidesk to package and deliver all apps to go "all in" on XenApp shared hosted desktops.
  3. Use Unidesk to package and deliver all apps to deploy XenDesktop VDI for some use cases and XenApp shared hosted desktops for other use cases.

What do you think? Does this make sense? Or are you even more confused? Comment and let me know!

Topics: Citrix XenDesktop, Citrix XenApp

Posted by Jeff Pitsch on Nov 21, 2016

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