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What application virtualization can and can't do for you

Application virtualization fixes compatibility issues for Windows 7 migrations, improves desktop application security and eases management. However, it has its limits.

IT pros virtualize as many applications as they can to make management easier and eliminate application-compatibility...

problems, particularly when they migrate desktops to Windows 7. But not every application works well -- or at all -- when virtualized.

Having a single point of management for updates and troubleshooting on the back end is simpler than managing individual workstations. That's why Ryan Koelewyn, an IT network analyst in California's public sector, said he strives to virtualize 100% of his applications. 

The problems with conflicting apps and DLL hell go away with application virtualization; you know when you start the apps, it will work no matter what you have installed or not installed.
Paul CamachoIT architect, RA-Micro Software

Koelewyn found that virtualization eases administration so much that he uses Citrix XenApp to deliver almost every application his organization runs -- even those that aren't supposed to be virtualized.

"We have run into issues where some apps don't work, but anyone who is familiar enough with Citrix can find a way to hack it and make those apps work in a virtualized environment," Koelewyn said. "They don't work super great, but well enough to get the job done."

Application virtualization tools let administrators deliver incompatible apps to new platforms with very little testing, so the technology is useful for Windows 7 migrations, especially in large shops where there are hundreds of desktops to manage.

That could be why application virtualization is used in 57% of IT shops today, according to the 2010 Virtualization Decisions Survey of more than 800 IT professionals released last month by

Paul Camacho, an IT architect at Germany-based legal software provider RA-Micro Software, uses Seattle-based Spoon Studio (formerly Xenocode Application Studio) to encrypt and secure applications. Spoon's tool has come in handy for porting legacy apps from Windows XP to Windows 7.

"The problems with conflicting apps and DLL hell go away with application virtualization; you know when you start the apps, it will work no matter what you have installed or not installed," Camacho said. "It takes care of software reverse-engineering issues and takes weight off of IT team, so it's a great cost saver in that respect."

Application virtualization limitations

Unfortunately, some apps can't or shouldn't be virtualized. For instance, kernel-based device drivers won't work with any of the application virtualization products on the market today. Adobe Acrobat, for example, which has a printer driver, can't be virtualized.

Product Options

Several products are available for virtualizing applications. The most widely used are Citrix XenApp, VMware ThinApp and Microsoft App-V, according to the Virtualization Decisions Survey.  

When asked which desktop virtualization technologies they use, 29% of respondents said XenDesktop and XenApp, about 6% said they use Microsoft's App-V tool and Med-V tools, and 9% said they use VMware ThinApp, commonly used with VMware View, which 33% of respondents also said they use.

There are a number of sideline players with application virtualization products as well, including Novell's ZENworks tool, LANDesk Software and AppZero.

Microsoft advises against virtualizing Office plug-ins because they can cause technical glitches. Applications that require operating system integration are tough to virtualize as well.

In addition, 16-bit apps can't be virtualized at all. Though most apps are 32-bit and 64-bit, many shops still have 16-bit apps without even realizing it. A 32-bit process called ntvdm.exe is used to run 16-bit applications, but most IT pros don't know that unless they look for it, said desktop virtualization expert and blogger Brian Madden. Administrators can configure a Perfmon log to search for running instances of that exe file, he said.

Users can also find out which apps are compatible with different OSes and specific application virtualization products using a third-party tool such as App-DNA's Apptitude or Microsoft Application Compatibility Tool Kit.

Watch your licenses

Enterprises also need to be careful to not violate licensing rules with application virtualization. For instance, when licenses are tied to the machine's hard disk serial number, virtualizing that app could be a violation.

There has also been some chatter about whether virtualizing Internet Explorer (IE) 6 is a violation of Microsoft licensing, since IE6 is technically part of the Windows operating system, not an application.

Many IT pros use application virtualization tools from InstallFree Inc. to run IE6 on Windows 7, but according to Gartner Inc.'s interpretation of Microsoft's licensing rules, IE shouldn't be virtualized with any application virtualization tools.

It's a balancing act to figure out which applications to virtualize, but the flexibility benefits outweigh the complexities, said Jim Sanzone, a desktop and application virtualization consultant with a major integrator in New York.

Let us know what you think about the story; email Bridget Botelho, News Writer.

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