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The Mainframe Energy Efficiency Value: Part 2

Note: This is the second part in a two-part series. The first installment appeared in last month’s EXTRA, locatedhere.

In the first part of this article, we discussed the mainframe’s design advantages and component efficiency and how they increase the system’s overall energy efficiency. In this article, we’ll delve further into the mainframe’s energy efficiency by exploring virtualization.

The Ability to Virtualize

With more than 40 years of virtualization experience, IBM mainframes have gotten pretty good at the virtualization game. (Virtualization is simply the pooling of unused resources.) Mainframes set the industry tone for virtualization—all other virtualization schemes are followers of the path that mainframes have already blazed.

Voluminous books can be written about how mainframe virtualization works, how flexible mainframe virtualization is and how efficient virtualization enables a mainframe to become. But for the purposes of this article, consider only these two aspects of mainframe virtualization: granularity and virtual I/O capability.

System virtualization is all about finding unused computing power and exploiting it. So if a processor is available for work then that processor should be pooled and made available to process other workloads. Mainframes not only make entire processors available to process work, they make portions of processors available for work. So, if a small workload comes along and there is 10 percent of a processor not being utilized, a mainframe will make that processor available to process that small workload. This isn’t the case with several other virtualization schemes on the market. And the bottom line is, the busier you can keep a system that’s already burning energy, the wiser you are about using your electric power.

Virtual I/O is also important as it relates to energy savings. Virtual I/O enables a mainframe to share I/O and network resources with clients. By doing this, administrators can use fewer physical adapters to communicate over the network or through an I/O subsystem with other devices (disk adapters and disk drives). The primary benefit of Virtual I/O is to reduce costs associated with acquiring a wealth of redundant devices in order that each virtual machine have a physical network or disk interface through which to communicate with the outside world. But Virtual I/O also saves energy in that additional devices need not be physically present and need not constantly burn power while waiting to serve virtual machines.

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