Citrix XenDesktop 3.0 brings a small technology advantage to our Rolling Review of virtual desktop infrastructure products.

The successful integration of XenSource, now called Citrix XenServer, coupled with the dominant position of XenApp (formerly Presentation Server), helps XenDesktop 3.0 take full advantage of the ICA protocol to stream virtual desktops to clients. Its virtual desktop infrastructure, or VDI, competitors use the RDP protocol. While RDP 6.0 has closed the gap, ICA still lends itself to a better virtual desktop experience.

As is the case with VMware ESX and Microsoft's Hyper-V, it's a snap to build the back-end server virtualization components required to host virtual desktops. The XenCenter management module is noticeably speedier and more responsive than VMware's VirtualCenter client. Like VMware's VDI, Citrix doesn't tie you into using XenServer as a back end; you can use ESX or Hyper-V if you prefer.

Getting XenDesktop ready to serve out virtual desktops required some heavy lifting, though, compared with VMware VDI. Two core XenDesktop server components make the magic happen, and Citrix recommends that each be run on its own physical hardware. The Provisioning Server component manages the base virtual desktop images and provides significant deduplication capabilities.

Once we completed building our base virtual desktop with XenServer, we could quickly image it to the vDisk format that the provisioning server uses to launch subsequent static and pooled virtual desktops. As users make changes, add software, and generally bloat the size of their user profiles within the operating system, the results of those changes are added to a separate file instead of to the base image. This allows IT to freely update the global image with critical updates and patches while preserving individual user environments inside a well-compressed sandbox.

The Desktop Delivery Controller server is the second piece required to complete the XenDesktop puzzle. The DDC is responsible for authentication, connection brokering, and Web accessibility to user virtual desktops. While there are plenty of moving parts here, Citrix does a good job automating as much of the heavy lifting as possible. Admins used to managing a Citrix Presentation Server or XenApp environment will feel right at home managing a XenDesktop environment.

Rolling Review

VIRTUAL DESKTOP INFRASTRUCTURE TOOLS

Business value
We're testing several virtual desktop infrastructure products' ease of installation, functionality, and security.

Reviewed so far
• VMware VDI 2.1:
Server virtualization stalwart has strong desktop chops, too.

• Citrix XenDesktop:
Built-in multimedia enhancements ease the virtual desktop experience for clients.

Still to come
Virtual Iron, Parallels, Provision Networks, Stoneware, Sun, Synchron

More about this rolling review >>

The last step in the process is to distribute the Desktop Receiver client to all workstations. The Desktop Receiver is an offshoot of the Citrix XenApp client and deploys quickly. Based on login credentials, you can force users via single sign-on directly into their virtual desktops in full-screen mode, an experience that's indistinguishable from that of their normal desktop. Alternatively, users can launch their desktops within a traditional remote desktop-like window from their thick- or thin-client operating system.

Latency Resistant
In the lab, we found XenDesktop to be a tad more resistant to network latency than the RDP 6.0-based desktops served out by VMware VDI 2.5. But to be fair, we've yet to test VMware View 3 in the lab. In addition, the deduplication capabilities that distinguish XenDesktop 3.0 from VDI 2.5 are available in View 3.

The feature gap between core VDI infrastructure capabilities is fairly narrow among the players in this Rolling Review, but Citrix might gain an advantage in the third quarter, in the form of its HDX technology for virtual desktops. If Citrix can make good on its promise to deliver a rich 3-D user experience coupled with the ability to serve out computer-aided design and other graphically intensive applications via XenDesktop, VDI as a technology might finally get beyond being a niche solution for serving out Windows apps and other nonterminal services-friendly apps.

On the whole, we were impressed with XenDesktop 3.0, and we love that fact that Citrix has chosen to give XenServer 5.0 Enterprise away for free. But while that strategy will certainly put the squeeze on VMware, and even more so on Hyper-V, XenDesktop is still by no means cheap after you add up the hardware, storage, and Windows and XenDesktop licenses required to get up and running. XenDesktop 3.0 Standard Edition lists for $75 per concurrent user. As you add premium features like virtual application delivery and quality of service, list pricing ranges from $195 to $395 per concurrent user.

Randy George ([email protected]) is an industry analyst covering security and infrastructure topics.

Our Take

CITRIX XENDESKTOP 3.0