As the global economy is recovers, pent-up business demand for new apps and market initiatives is driving server investments. Forrester finds that 25
percent of organizations expect server spend to grow by 5 percent to 10 percent, and 6 percent expect it to grow by 10 percent or more. And to reduce
operating and capital costs, improve disaster recovery, and accelerate time-to-market for new apps, organizations are turning to server virtualization.
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But a new motivator to expand and improve the use of server virtualization is bubbling to the surface: reducing energy consumption. Why? Forrester
finds that there are three primary motivators:
• Financial. The costs to power and cool a server over its life may actually exceed its purchase price. Virtualization reduces the overall energy
consumption of your server footprint, thereby allowing the same workload to run on fewer physical, energy-consuming servers.
• Resiliency. To ensure that uptime and service-level agreements are maintained, virtualization alleviates out-of-space, power, and cooling
• Green. Virtualization reduces the overall server footprint and cuts energy-related carbon dioxide emissions as well as the electronic waste from
purchasing and then disposing server equipment in the future.
To cut server energy costs by up to 65 percent and exploit your energy savings potential from virtualization, Forrester recommends three process
1. Increase your overall virtual-to-physical server footprint.
There are significant opportunities for organizations to increase their overall virtualization footprint across all server environments and platforms. We found
that, while approximately 90 percent of firms are virtualizing or planning to virtualize their servers, only 37 percent of their x86 operating system instances
are virtual servers. In two years time, this is expected to increase to 65 percent.
Additionally, the extent of virtualization varies significantly based on the server environment, and the platform. The first step to maximizing energy
savings is to increase the overall virtualization footprint across all environments and platforms. To ensure you’re actually saving energy, be sure to turn off
or decommission servers that are no longer running any workloads. Forrester’s Green IT maturity assessment
methodology prescribes the following virtualization targets to achieve one of four levels of green IT maturity: 1) Needs improvement (1 percent to 25
percent virtualized); 2) Improving (26 percent to 50 percent virtualized); 3) Robust (51 percent to 75 percent virtualized); and 4) Best-in-class (76
percent to 100 percent virtualized).
2. Maximize your virtual machine to physical host and utilization ratios.
Virtualization alone is not enough. In addition to increasing the overall server virtualization footprint, drive additional energy savings by virtualizing more
efficiently. Server virtualization ratios are not keeping pace with modern hardware and virtualization platform capabilities. It’s common to break even on
the purchase of a new server with a 4-to-1 virtual machine (VM)-to-physical host ratio, but most servers can accommodate 15 VMs. Virtualizing more
efficiently can help you avoid three new server purchases, not to mention the additional power, cooling, and space expenses from this new equipment.
A key ratio that administrators use to determine the acceptable number of VMs per physical host is server CPU utilization. There is a direct
relationship between CPU utilization, VMs per physical host, and energy savings. A standalone unvirtualized server might run at an average of 10 percent
to 15 percent utilization, whereas virtualized servers could theoretically approach 100 percent. However, Forrester finds that most administrators are
hesitant to push the utilization of their physical host servers beyond 25 percent to 50 percent — limiting both the number of VMs per physical host
and energy savings potential. Underutilized servers still consume considerable amounts of energy.
If you increase the number of VMs per physical host, you can decrease the total number of physical servers and reduce energy consumption. As
server teams become more comfortable with higher server virtualization utilization ratios, they can safely add more VMs per physical server without
diminishing service levels.
3. Source more energy-efficient servers and architectures.
Sourcing more energy-efficient servers and architectures may be your only remaining option to reduce energy consumption if you’ve maxed out
virtualization ratios or realized that youre going to need higher-end server infrastructure. Energy consumption will be higher on a per-server basis
— but total server energy consumption will be lower due to the reduced number of overall servers. If your risk tolerance doesn’t allow you to push
the limits of virtualization ratios, then these more efficient server environments may be your only viable option.
Forrester recommends seeking newer models of the same servers your organization already purchases. The simple act of server refresh will reduce
server energy consumption. New server architectures, such as blade systems and converged infrastructure, are not only more energy-efficient by nature
but also facilitate aggressive virtualization.
The energy savings can be impressive, as noted by a VP of an online services company who said about his converged architecture: “We achieved 70
percent space savings, 25 percent operational expense savings, 30 percent to 40 percent heat dissipation improvements, and 40 percent power
Doug Washburn is an Analyst a Forrester Research, where he
serves Infrastructure and Operations professionals.
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