Citrix Addresses Performance with XenApp 5

Published: August 27, 2008

by Alex Woodie

Citrix Systems this week unveiled a new release of XenApp (formerly Presentation Server) that addresses performance concerns users have expressed when remotely accessing their Windows desktop applications. With XenApp 5, which ships September 10, Citrix says it has improved application start-up times, added a new "preferential load balancing" feature to ensure critical applications get the most resources, and simplified maintenance of user account settings. Citrix claims the improvements combine to make a "better than installed" experience when combined with other Citrix products.

If you've been around the IT space for any length of time, chances are good that the name Citrix conjures up memories of the old MetaFrame/Presentation Server product, which uses Citrix's Independent Computing Architecture (ICA) protocol to make users sitting at Windows desktops think they are working on locally installed applications, when in fact the applications are running on a Windows server thousands of miles away. Each user's mouse and keyboard clicks are sent up the wire, and the screen image is sent back down.

And if you have experience with this type of computing, chances are good you're familiar with some of the drawbacks and limitations, most notably sluggish performance compared to running on a local OS. That's not to say there aren't benefits. There are huge benefits, including the fact that administrators don't have to physically visit each location to maintain users' desktops, which is why Citrix counts 98 percent of the Fortune 500 companies as customers, and has more than 100 million users on 1 million servers. But to say the desktop experience of Citrix users was equal to that of standard Windows desktop users would overlook obvious differences.

Today, Citrix is doing its best to change that perception--as well as the underlying reality--with the "Xen-ification" of its tools. Citrix's $500-million purchase of XenSource last year was a huge step forward for the Ft. Lauderdale, Florida, company, and now the company is doing its best to bake Xen's technology into all of its tools, with the goal of providing a complete virtualization offering that extends from the desktop to the data center (which is embodied within the "Citrix Delivery Center" suite).

Citrix engineers made a giant leap toward this goal earlier this year with XenApp version 4.5, which gave customers the choice of accessing applications running on a remote Windows server, or accessing a local copy of the software that has been "streamed" down to the desktop from the server. This use of virtualization technology has arguably had the biggest impact on how Citrix customers can consume Windows applications.

With the release of XenApp 5, Citrix engineers have made iterative improvements over version 4.5, and given XenApp customers more tools to ensure performance levels, particularly for streamed applications (as opposed to traditional ICA). There's only so much Citrix can do to improve upon the core ICA offering, and it looks like most of the 50 or so enhancements in XenApp 5 deal with application streaming, which is arguably the future of desktop virtualization.

When using application streaming with XenApp 5, Citrix customers can improve their users' start-up times by up to a factor of nine, the company says. When using the Branch Repeater--a WAN acceleration device that installs at branch offices--streamed XenApp 5 applications can get to Windows desktops up to 40 times faster.

Using the Branch Repeater as a local load point makes a lot of sense for heavily used streamed applications, says Bill Hartwick, senior director of product marketing for Citrix. "In the beginning of the day, when the various branches are all coming on line, the individuals are going to want the closest location [to update their applications], as opposed to having to go all the way back to the centralized data center," he says.

Thanks to a new feature in XenApp 5 called "linked profiles," Citrix says it has reduced the server and personnel footprint required for running streamed applications by up to 25 percent. In previous releases, a single application bundle would be used for each user or desktop. Whenever there's a change to one of the applications in the package, such as SAP ERP client or Adobe Acrobat, the entire package had to be updated.

With linked profiles, only the individual application requiring the update needs to be re-streamed down to the user. What's more, only the parts of the application that have changed need updating with XenApp 5, Hartwick says. "Rather than package them together, we package them separately," he says. "This greatly simplifies the demand for the virtualization application, reduces support costs, and improves performance to the end point."

While application streaming is the focus of XenApp 5, the new version also includes an enhancement to the traditional hosted ICA form of computing. With preferential load balancing, administrators can ensure that critical Windows applications that consume higher amounts of server resources are not bundled on the same server, thereby hurting performance.

Hartwick uses a graphical X-ray application in a hospital setting as an example of a critical application. "When a new person comes on board, where would this session go?" he says. "It may end up over on the same server as this person here. But that is going to set up potential contention between those two for the resources on the server, be they CPU, graphics, etc. With preferential load balancing, you can assign prioritization. In this case, these two applications cannot run on the same machine, so it'll split them on different servers. So you get a good optimized experience for the end user, and eliminate the need to have separate servers for the applications."

XenApp 5 also includes new monitoring and management tools aimed at helping IT administrators track down problems. If performance of a hosted application or streamed application appears to be degrading, administrators can use a new "synthetic session" feature in XenApp 5 to re-create the user's session, which will help them track down the problem.

Citrix also brings support for Windows Server 2008 (including 64 bit versions) to XenApp with version 5. Customers can mix and match Windows Server 2008 and Windows Server 2003 operating systems to run their XenApp workloads, allowing them to upgrade to the new OS at their own pace and avoiding the need to perform wholesale, or "forklift" upgrades to Windows Server 2008, Hartwick says.

Citrix also enhanced the Web interface with version 5. The Web interface, which is an option in the Platinum edition of XenApp, functions mainly as a directory that enables users to access their XenApp applications from any computer or device with a Web browser. The Web interface is seamless across Windows and Mac operating systems, and allows users to access their applications regardless of the OS.

That's the ultimate goal of Citrix: to eliminate the boundaries that restrict where, when, and how users access applications and data. "From an end-user standpoint, it's "I don't know and I don't care,'" Hartwick says. "I just start them up like they were any other application."

Citrix is pushing the combination of XenApp--which is now 20 years old--with its XenDesktop (client virtualization) and XenServer hypervisor products. In fact, the combination of these products is likely to be a central theme to its big "Citrix Delivery Center Live" launch event, which is being held September 9.

Hartwick explains how the technologies come together: "One of the key advantages of using Citrix technology is using XenApp together with XenDesktop, to stream those applications to the virtual desktop in the data center, and deliver the consolidated experience out to the end point," he says. "You're able to manage fewer application images, and able to drive that out to the virtual desktop, and dynamically assemble them and deliver them out to end user, giving that sort of 'brand new PC every time' experience."

XenApp is available now. Pricing ranges from $350 per desktop for the Advanced Edition to $600 per desktop for the Platinum Edition.

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