Small to medium-size businesses have been behind the curve when it comes to adopting virtualization, but this technology can deliver significant benefits to companies of nearly any size because it allows the enterprise to make more efficient use of IT resources. A virtual machine consists solely of software, yet it has all the components of a physical machine: It has a motherboard, a CPU, a hard disk, a network controller, and so on. The operating system and other applications run on a virtual machine just as they would on a physical machine--they see no difference between the two environments.
How does virtualization make more efficient use of your IT resources? Servers are designed to accommodate peak--versus average--loads, so they’re underutilized most of the time. In fact, the typical server utilizes only between 5 and 15 percent of its overall resources. Running several virtual machines on one physical server uses those resources more efficiently, boosting utilization to between 60 and 80 percent.
Virtualization eliminates the need for additional physical servers, and the tech-support overhead, power, cooling, backup, physical space, and other requirements that go along with them.
Here are the reasons why virtualization is no IT cure-all. 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.
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, affecting multiple operating systems, multiple applications and those little tiny fires will turn into big infernos fast," Coyle said.
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 creates a dynamic environment without such guarantees. At any given time, performance of an application could degrade, perhaps not to a failure, but much slower than desired.
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.
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?"
No standardization. Tools and processes used to address the physical environment can't be directly applied to the virtual world, so many IT shops will have to think about standardizing how they address issues in the virtual environment.
"Mature tools and processes must be revamped," Coyle said.
Virtual machine sprawl. The most documented side effect to date, virtual server sprawl results from the combination of ease of deployment and lack of life-cycle management of virtual machines. The issue could cause consolidation efforts to go awry when more virtual machines crop up than there are server administrators to manage them.
"The virtualized environment is in constant flux," he said.
May be habit forming. Once IT organizations start to use virtualization, they can't stop themselves, Coyle said. He offered tips to help curb the damage done from giving into a virtual addition.
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