Server Virtualization: 6 Management Myths

Hint: You don't really know what hypervisors you're running, or what it all costs. Consider some expert advice on 6 common management mistakes.

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2. That big ROI will drop off.

Virtual servers continue to work more efficiently than physical servers, and make better use of the hardware that's already bought and paid for. But the huge return on investment many companies get when they first convert P to V in one department or data center — and usually repeat in each stage of a multi-phase migration — does not renew itself every year or every time the company has to replace its servers, according to James Staten, vice president and principal analyst at Forrester Research.

"When you're doing lots of physical to virtual migrations you're getting massive cost savings. When you get beyond the point of taking lots of servers out, that drops off," Staten says.

Business units get used to the high payoff from a drop in capital costs, and usually don't pay much attention to the portion of the operational budget that often has to rise to accommodate virtual infrastructures, Chen says.

The dropoff in ROI and increase in operational costs that happen when IT finishes the last stage of a phased-migration to virtual servers and begins simply to support them can make IT look as if it's suddenly costing the company more money, Chen says.

"IT ends up having to explain, hopefully ahead of time, why support or ops costs might go up," he says.

3. Licensing costs can multiply.

Virtual servers are cheaper to move and store, but they're still servers and still cost as much as any other server for software, operating systems and management, Staten says.

In fact, even licensing costs can get out of control for companies that go hog wild on the power and flexible capacity virtual servers can deliver by launching more servers and application instances than their budgets will bear.

"If you've paid for 500-servers worth of one license, and used 600 and the trend is toward a lot more, you see a big bill coming," Staten says. "There is a lot of renegotiating of enterprise license agreements going on for that reason."

The volume of servers involved was a key reason Target decided to use Microsoft's Hyper-V as its primary virtual-server product, rather than VMware."Cost actually is a big part of the reason we opted to go with Hyper-V," Target's Thompson says. "Every store has its own, relatively small footprint, and costs involved with the applications and servers. If you multiply it by 1,755 stores, that becomes a very large number quickly if you don't pay attention to controlling costs."

Even after the money saved from replacing seven physical servers with two, paying additional licenses for the Windows licenses for two host machines and the OS on each VM, multiplied by almost 1,800 stores, is a big bill, though Thompson wouldn't say how big.

Running Hyper-V, which comes free as a feature in Windows Server 2008, "saves us millions in operating expenses per year, and it uses the same management tools, with the same skill sets, we use already," Thompson says.

"Every server has a base license — for Windows or VMware — and another for every guest OS and application," Chen says. "It's virtual; it's not free."

4. Management chores will change, not evaporate.

One of the major theoretical benefits of virtual servers is that they're easier to manage than physical servers because they can be launched, reconfigured and monitored remotely more easily than physical servers, reducing the workload and size of the staff required to maintain them. "That's the assumption, but what our surveys show is that the number [of respondents] saying virtualization has made management easier has been stuck at around half for three years," Olds says.

Specifically, according to Olds' data, only 52 percent of x86-based virtual server users said VMs made their overall server-management load lighter, while 25 percent say VMs made server management harder. Almost as many, 22 percent, aren't sure whether management is easier or harder.

"What's not clear is whether that's because it gets more difficult to manage the servers when customers jam more and more workloads on the same systems, or if the management tools that are available aren't up to the job," Olds says.

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