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Virtual Sprawl
That's not to say that virtualization projects are easy. Myriad issues need to be ironed out before more CIOs consider virtualizing their mission-critical applications and, ultimately, their entire data center. First, some applications don't perform well in virtualized environments, such as large databases, anything I/O intensive, and large-scale applications that require their own machines. Virtual machines are also another layer of software and have their own resource requirements; thus there's an additional drain on I/O performance. Some IT vendors can add to the problem. "They'll promise that 12 virtual machines can be put on a processor, and the reality is about six" in most cases, says Brudzynski.
Another pitfall surrounds licensing. "We have talked to a few executives who were breaking the law, and they didn't even know it," says Brudzynski. "Basically, it has to do with CPU charges. Your host, your physical server, might have four CPUs, even though the virtual machine has one."
Licensing is often married to the number of instances, or images, a company is allowed to run, or the number of processors per machine, explains Al Gillen, an analyst at IDC. "If your license says you can only put one image down, you can't put two images down just because you have two virtual machines," Gillen says. Most vendors' pricing works this way.
But in 2005, Microsoft launched a per-instance instead of a per-processor licensing policy. EMC'sVMware has the lion's share of the virtualization market; EMC is aware of the potential licensing problems for CIOs and has begun working with several vendors to change licensing structures, he says.
Still, complying with licensing requirements is one task that can stymie busy midmarket CIOs. "From a CIO's perspective it's a very complex thing,'' says Gillen. "Here's the real zinger: You may have figured out which licenses you have in place, and tomorrow you decide you are going to move one application from a machine to another and find out your licensing is not compatible with your new scenario."
Though many CIOs report few problems with their server virtualization projects, Gillen says that many could be headed for licensing headaches. "That euphoria you are hearing is associated with virtualization 1.0. Virtualization 2.0 is going to mean you have to manage these systems. As soon as you start talking about moving stuff from one machine to another, that ugly licensing issue comes back to haunt you."
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