The Virtues of Virtualization

Virtualization is a technology that provides benefits in many areas. Specific areas where you may realize positive gains include:

• Server consolidation
• Improved Energy Efficiency
• Better Utilization of Resources
• Improved Operational Flexibility
• Improved Disaster Recovery and Security

Server Consolidation

Virtualization makes it possible to provision multiple workloads onto fewer physical machines. This change can reduce the number of servers, the number of locations where servers are installed, the quantity of software licenses required, and the number of points where management resources are needed. A reduction in the number of physical machines reduces energy consumption and improves energy efficiency.

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Improved Energy Efficiency

Virtualization is a principle factor in increasing energy efficiency within the data center. Common estimates attribute up to 25% improvement in energy efficiency after virtualization technology and practices are applied.

Data centers have many complex, interconnected systems when analyzed from an energy supply and demand perspective. The IT equipment (demand) requires energy in the form of power and cooling from the infrastructure (supply).

Reductions in energy requirements on the demand side result in a cascade effect which produces an energy savings in the supply infrastructure that is greater than the demand savings. A common estimate is that for every watt saved on computing infrastructure, 1.5+ watts are saved on power and cooling infrastructure (see Figure 2).

Virtualization reduces the number of servers necessary to service a given number of workloads, and it more efficiently uses the resources of each virtualized server.

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Better Utilization of Resources

Many of today's servers use 60–70% of their maximum power even while at idle. With modern, multi-core processors, it is easy to establish a ratio of one workload to one processor core, which, when compared to the common "one workload per box" provisioning standard for an average, dual-socket server, translates to a consolidation ratio of 8 to 1.

Virtualized servers use energy very efficiently. They can service many workloads for a relatively small, incremental increase in power consumption. In addition, server consolidation allows power supplies to operate in their highest efficiency ranges (many server switching power supplies don't reach peak efficiencies until power output is 50% of max or greater).

With virtualized servers, each server is more likely to be using a majority of its physical resources: it is less likely that one server will be running out of processor resources while another has processing capacity to spare. Having fewer servers creates an opportunity for fewer software licenses, or the opportunity to ensure better utilization of software licenses. Many server operating systems allow for more than one virtual OS install with the purchase of a single physical OS license.

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Improved Operational Flexibility

Virtualization allows IT administrators to spend less time on repetitive tasks such as configuration, provisioning, monitoring, and maintenance. Hardware is abstracted from the virtual machine, allowing multiple operating systems to be natively installed onto server hardware that might otherwise have compatibility issues. Older operating systems and legacy applications can be installed onto newer, more reliable hardware.

Migrating virtual environments can be accomplished with greater efficiency and no interruptions in service. Workloads can be placed on the most appropriate system. Applications can be encapsulated into virtual entities with their operating system, performance parameters, and security environment.

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Improved Disaster Recovery and Security

Traditional system-level disaster recovery relies on a backup, usually to a tape device, or over the network to a tape or backup volume. When a disaster happens, the recovery process often takes a considerable amount of time, and depending on the application, may require matching hardware to successfully recover the failed system. With virtualization, backup can be accomplished at the host level, with the whole virtual machine being copied, even while the system is running. The backup is an image of the virtual machine, which can be restored quickly and effectively to another virtual machine on another system. Because hardware is abstracted in the virtual environment, it is not necessary to have matching hardware on the target restoration system, nor is it necessary to prepare the target system at the service level to match the original system. This saves time, which is often the most critical factor in disaster recovery.

Virtualization can offer greater security and stability through application isolation. Because a single application can be encapsulated into a virtual machine, issues of stability, resource waste, and security can be isolated and not result in a system crash, application compromise, or system compromise. When a virtualized application is compromised, the underlying operating system is not affected, which allows administrators to quickly restore the system image and return the server to production.