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Citrix XenApp and XenDesktop on VMware vSphere: Peaceful coexistence

One way to try desktop virtualization is by running Citrix XenDesktop on VMware vSphere. Explore XenApp on VMware, too.

Citrix XenDesktop and XenApp are to desktop and application virtualization what VMware vSphere is to server virtualization:...

market leaders. If you’ve standardized on VMware vSphere for server virtualization, it’s critical to learn how technologies such as Citrix XenApp 6.5 and XenDesktop 5.5 can work in your VMware infrastructure.

Plus, running XenDesktop on VMware or XenApp on VMware is even supported. Each of these Citrix tools can help administrators consolidate hardware, improve flexibility and manage their environment better. Here’s how you can take advantage of a powerful combination:

Running XenApp on VMware

VMware’s feature set is very similar to that of XenServer 6.0 and is compatible with the latest release of XenApp 6.5. You are effectively deploying a Windows Server 2008 R2 virtual machine (VM) with XenApp installed on top of it. By running Citrix XenApp on VMware, administrators can centralize the management, administration and delivery of Windows-based applications, while using their existing server virtualization platform.

So, why deploy XenApp on VMware vSphere, rather than on bare-metal? As with any multi-tiered application, XenApp can be spread across many individual servers, or consolidated into a few. Hardware sprawl takes a toll on many environments, and admins look to offload their physical servers. Consolidation is also often driven by higher capacity server hardware and the fact that most applications cannot fully take advantage of the resources provided. With VMware vSphere, you can consolidate applications and better allocate their resources.

For the VMware administrator who’s new to Citrix’s tools, XenApp consists of the following components:

  • Licensing Server: Required for all XenApp deployments.
  • Data store: The database where information is stored, such as configuration information for published applications, users, printers and servers.
  • Data collector: This maintains information such as license usage, session status, server loads, connected users and published applications.
  • Web interface: Required when users access apps using the online plug-in or a Web browser.
  • XML service and broker: The intermediary between the Web interface and XenApp servers.
  • Application servers: These host the published applications to which users connect.

Deploying XenApp on VMware vSphere means you can isolate each role in its own VM and operating system. This allows you the greatest flexibility and number of deployment options. Using the vCenter management console, you can monitor and manage the amount of users per server and allocate resources where needed.

In addition, consider using tools such as Citrix EdgeSight for Load Testing, which can simulate user load when running XenApp on VMware vSphere. Proper load testing -- using characteristics that closely resemble the expected workload -- is critical to obtaining data about the optimal user density.

Running XenDesktop on VMware vSphere

Much like XenApp, vSphere also fully supports Citrix XenDesktop 5.5. This Citrix offering allows administrators to deliver multiple types of virtual desktops in their VMware infrastructure.   

Here are the components of Citrix XenDesktop you need to know:

  • Desktop Delivery Controller: The Desktop Delivery Controller provides the link between the Web interface and the XenDesktop site.  The controllers keep track of resources for each end user and direct user launch requests to the appropriate virtual desktop.
  • Web interface:  The Web interface provides user access to the XenDesktop environment.  It accepts user credentials and passes them on to the XenDesktop site for authentication and enumeration.  It is recommended that at least two Web interface servers are deployed per data center, for high availability.  Ideally, Citrix NetScaler should be used to load balance traffic between the Web interface servers. 
  • Virtual Desktop Agent:  The Virtual Desktop Agent (VDA) is a software agent that resides on the virtual desktop and provides the communication interface between the XenDesktop infrastructure and the Windows OS. 
  • SQL database:  The Microsoft SQL database provides the foundation for XenDesktop. It holds all the configuration, virtual desktop and resource utilization information. 
  • Citrix Licensing Server: The License Server is responsible for managing the licenses for all XenDesktop 5.5 components.
  • Citrix Receiver:  Citrix Receiver is easy-to-install client software that lets you access enterprise data, applications and desktops from devices including iPhones, Android-based smartphones, iPads, Windows Mobile devices, Blackberry; and Windows, Mac OS X or Linux desktops.
  • HDX Technology: HDX technology delivers a high-definition end-user experience  for any application, device or network.

VMware vCenter allows administrators to configure resource clusters and manage storage and high availability across the environment.  Since VMware vCenter requires a SQL database, XenDesktop and vCenter can share the same SQL server infrastructure. 

But running XenDesktop on VMware comes with a caveat: You must install VMware Tools before installing the XenDesktop VDA (Virtual Desktop Agent).  Both VMware Tools and the XenDesktop 5 VDA install a Windows Display Driver Model (WDDM) display driver.  XenDesktop requires the Citrix WDDM driver to function, and installing VMware Tools after the VDA will remove the Citrix driver.

Running XenApp or XenDesktop on VMware vSphere can help you boost performance and implement desktop or application virtualization in your infrastructure. Some tools are easier to combine with vSphere than others, and Citrix’s supported products are a good place to start.

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