Server Virtualization Simplified

'Virtualization’ is a broad term that refers to the abstraction of computer resources (1). Virtualization, also sometimes referred to as server consolidation, is the concept of one physical computer servicing several applications and allowing each to use the same underlying hardware without interference with one another. Virtualization allows for different applications to have sufficient hardware resources - central processor units, memory and I/O, the essential physical resources to run an application. Virtualization also lets you host multiple operating systems on the same hardware. The general idea is analogous to time sharing – each application has shared use of the hardware.

Virtualization was developed initially for the mainframe hardware in the 1960’s to increase utilization. In the 1990’s a company named VMware developed the capability on x86 hardware or Intel processor based hardware. Only approximately 5% of servers have been virtualized, but the technology has matured and is becoming more main stream.

Most servers today are in use only 8-15% of the time, yet they consume 60-90% of the workload power even when idle (2). Typically, a server will host a single application and is sized for peak load (e.g. month end processing), but will sit idle for much of the day (e.g. when users are off shift). As the servers idle they still require significant power and this is wasted energy. Estimates show that a single server virtualized can save as much as 7,000 kilowatt hours per year. With a million servers virtualized this results in an aggregate power savings equal to the electricity consumed in New England for one year (2). Several utilities within the United States offer financial incentives for server consolidation, based on the net reduction in power usage.

There are several other benefits of virtualization, such as the agility of deployment and the ability to quickly deploy virtual images to alternate hardware (e.g. after a hardware failure). For example, rather than waiting on hardware purchasing lead time, a new image/application can be deployed within minutes using existing hardware resources. This can be a very beneficial feature for application testing purposes.

Some of the challenges, or downside, with virtualization includes increased complexity, potential for compatibility issues (i.e. where certain workloads cannot co-exist) and a new set of IT skills.

Below are some sites to visit for more information about virtualization.

VMware

Microsoft 

Xen 

References

(1) Wikipedia

(2) VMWare http://www.vmware.com/solutions/consolidation/green/

By Jamie Johnson

Jamie Johnson is an associate partner at IBM and an active volunteer in the promotion of renewable energy and sustainability of our planet. Jamie writes articles and whitepapers for the GreenITTools.com website.

Virtualization plays a signification role in reducing the environmental impact of your IT resources.  Check out the Green IT Guide and Toolkit for Sustainable Business for more about the energy and cost savings Green IT offers.