David Coyle, research vice president at Gartner, detailed the seven side effects at the research firm's Infrastructure, Operations and Management Summit, which drew nearly 900 attendees. While virtualization promises to solve issues such as underutilization, high hardware costs and poor system availability, the benefits come only when the technology is applied with proper care and consistently monitored for change, Coyle explained.

Here are the reasons Gartner says virtualization is no IT cure-all:

1. Magnified failures

In the physical world, a server hardware failure typically would mean one server failed and backup servers would step in to prevent downtime. In the virtual world, depending on the number of virtual machines residing on a physical box, a hardware failure could impact multiple virtual servers and the applications they host.

"Failures will have a much larger impact, effecting multiple operating systems, multiple applications and those little tiny fires will turn into big fires fast," Coyle said.

2. Degraded performance

Companies looking to ensure top performance of critical applications often dedicate server, network and storage resources for those applications, segmenting them from other traffic to ensure they get the resources they need. With virtualization, sharing resources that can be automatically allocated on demand is the goal in a dynamic environment. At any given time, performance of an application could degrade, perhaps not to a failure, but slower than desired.

3. Obsolete skills

IT might not realize the skill sets it has in-house won't apply to a large virtualized production environment until they have it live. The skills needed to manage virtual environments should span all levels of support, including service desk operators who may be fielding calls regarding their virtual PCs. Companies will feel a bit of a talent shortage when moving toward more virtualized systems, and Coyle recommends starting the training now.

"Virtualized environments require enhanced skill sets, and virtual training across many disciplines," he said.

4. Complex root cause analysis

Virtual machines move -- that is the part of their appeal. But as Coyle pointed out, it is also a potential issue when managing problems. Server problems in the past could be limited to one box, but now the problem can move with the virtual machine and lull IT staff into a false sense of security.

"Is the problem fixed or did you just lose it? You can't tell in a virtual environment," Coyle said. "Are you just transferring the problem around from virtual server to virtual server?"