Citrix XenDesktop 2.1 delivers virtual Windows XP or Vista desktops to users, thereby centralizing OS and application management tasks such as OS and application updates and patches while also significantly reducing help desk calls by preventing permanent end user tampering.
Even though XenDesktop 2.1 provides a good desktop virtualization infrastructure platform-aptly doling out clean desktops to users in a snap-my tests at eWEEK Labs showed that desktop virtualization doesn't fall into the same category of "must-do-now" technology as server virtualization. IT managers shouldn't be stampeded into thinking that just because "virtualization" appears in a product name that it will provide the same level of hardware or operational savings that the much more familiar server virtualization provides. The main reason: there are a lot more moving parts when it comes to a virtual desktop compared to server virtualization. In addition, aside from the complexity and fast-changing nature of desktops compared to servers, there are the license costs.
In particular, Citrix XenDesktop Platinum Edition clocks in at $395 per concurrent use and requires a significant physical infrastructure on the backend. The Enterprise Edition, which includes secure remote access (using Citrix's ICA protocol only) and XenApp-Citrix's application streaming and virtualization tool-is $295 per concurrency. It's worth pointing out early that the virtual desktops can be stored and run from VMware's Infrastructure 3 or Microsoft's Hyper-V environment; there is no need to exclude XenDesktop from consideration in environments not using Citrix's XenServer hypervisor.
XenDesktop 2.1, which started shipping Sept. 17, 2008, does offer the potential to mitigate desktop management costs by enabling IT staff to deliver groomed desktops to end users who can be using anything from a thin client system from vendors such as Wyse or Hewlett-Packard, any Web-enabled client or even an old fat-client system that might otherwise have been too weak to run current applications. During my tests I created master base images, much along the lines of what I would do to get a master image ready for an ESD (electronic software distribution) system like Symantec's Altiris Deployment Solution, Avocent's LANDesk Management Suite or Microsoft's System Center Configuration Management Server. The big difference is that instead of rolling out the image to hundreds or thousands of systems and then running vast numbers of reports to check on deployment success, using XenDesktop 2.1 I created pools of virtual desktops that could be accessed by users.
Of course, nothing about desktop workloads is simple, but at least VDI products, including XenDesktop 2.1, keep the images close to IT. As VDI technology develops, this closeness is what could drastically cut helpdesk calls and significantly reduce the need to dispatch technicians for desk-side support visits.
VMware ranges on the competitive landscape with View, the latest version of its VDI offering. Other tools such as Qumranet's Solid ICE, and even Roaming Profiles used in a Windows Active Directory Domain, are worth considering if users must move from PC to PC with access to their personalized settings and desktop customizations.
However, IT managers with experience using Citrix Presentation Server (now called XenApp) will likely find a lot to like in XenDesktop 2.1 when it comes to keeping users happy with responsive desktops neatly delivered. Shops that need to support mobile workers who work offline will need to get the Enterprise Edition and work it out with XenApp, which can provide applications from a central location for offline use.
XenDesktop 2.1 includes the Citrix DDC (Desktop Delivery Controller), which is software that runs on a Windows Server 2003 system (as with all XenDesktop components, this system can be a physical system or a VM) and manages the connections between users on endpoint devices and the virtual desktops. In addition, the Citrix Provisioning Server enables the product to stream a single desktop image to create multiple virtual desktops and significantly reduces the amount of storage required to create the virtual desktops. This is the thin provisioning technology that enables Citrix XenDesktop to contain backend infrastructure costs. Citrix XenCenter is basically the equivalent of VMware's VirtualCenter or Microsoft's System Center Virtual Machine Manager. In fact, these three components can be interchanged for each other, and this flexibility is what enables XenDesktop 2.1 to use either VMware's or Microsoft's hypervisor infrastructure to store and run the virtual desktops handed out by XenDesktop.
Each virtual desktop must be installed with an agent that, when paired up with a Citrix Desktop Receiver or an embedded edition of the receiver on Windows XP or Vista fat-clients, enables the sharing out of virtual desktops to users on endpoint devices.
The Advanced Edition that I tested didn't provide the XenApp for Virtual Desktops. (The Citrix Platinum Edition provides integration with the Citrix EdgeSight for Endpoints monitoring tools, WANScaler for optimizing deployment connections for branch offices, GoToAssist for remote helpdesk support, and EasyCall, because Citrix owns technology that enables voice communication from inside their virtual desktops. Other components, including Citrix Access Gateway appliance, must be purchased separately.)
How I Tested
Although not required, I used Citrix XenServer server virtualization hypervisor to create my test environment. The core components of XenDesktop require Windows Server 2003. The first VM was a Windows Active Directory Domain Controller. I point this out because VMware's VDI solution also uses Active Directory to help with user identification and authorization. The second was the Citrix DDC, basically the heart of the XenDesktop 2.1 product. The third was the Citrix Provisioning Server. The Citrix DDC-the biggest single component in the XenDesktop 2.1 release-uses Microsoft's Active Directory to store configuration information and to manage the assignment of virtual desktops to users.
The Citrix Provisioning Server is the component that used my master desktop image to creating multiple virtual desktops that were then made available to my test end users. The Provisioning Server also caches any user-initiated changes while the desktop is checked out, protecting the underlying OS from tampering.
In my test, I used the Provisioning Server to automatically create a pool of virtual desktop systems based on a master base image of volume license version of Windows XP SP2. The virtual desktop creation process went off without a hitch. When I started up my virtual desktop systems on a both a laptop running Windows XP (the fat client scenario) and a PC running the Linux Ubuntu desktop OS, I got lightening fast response, both in desktop startup and in video/mouse/keyboard response. The quick startup wasn't surprising because I configured a pool of virtual desktops to be ready to go.
Using the DDC, I configured three of the five test virtual desktops to be sitting idle but ready to go during business hours. This means that the virtual desktops were already started and waiting for a user to connect. As test users logged on, the DDC automatically spun up another virtual desktop to keep the available pool full. The pool made efficient use of my physical resources without running CPU cycles unnecessarily while also keeping my management interaction with the system at just about zero.
eWEEK Labs Technical Director Cameron Sturdevant can be reached at email@example.com.