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Computerworld - Many of our past columns have centered on a recurring theme: increasing the value of IT without scaling cost, all while ensuring minimal risk to the business. In keeping with this theme, in this column we'll profile the concept of server virtualization as well as some potential uses in your organization.
Although virtualization has been available in the mainframe world for many years, it's a relatively new concept in the commodity hardware space. Server virtualization abstracts IT services (such as e-mail) from their respective network, storage and hardware dependencies -- all the factors that are traditionally overly complex, and costly to operate. Specifically, server virtualization enables multiple virtual operating systems to run on a single physical machine, yet remain logically distinct with consistent hardware profiles. The "host" operating system creates an illusion of partitioned hardware by executing multiple "guest" operating systems.
In the past year or so, key players have been aggressive about establishing their market presence. Albeit early, we're already seeing consolidation of the market. In February 2003, Microsoft Corp. acquired several Connectix products and established an immediate market presence with Virtual PC and Virtual Server (see story). Recently, EMC Corp. announced its acquisition of VMware (see story).
With these large players involved, this technology is likely to move fast, despite initial limitations on immediate adoption. Server virtualization will not be geared immediately for services that require a high degree of computational or network throughput. Cost might be a factor because most operating system and application licensing policies require one license per instance -- so you'll have to buy four software licenses if you operate four virtual servers. And since virtualized servers also require management of physical hosts, any shortcomings in systems management practices will need to be addressed quickly.

	Christopher Burry is technology infrastructure practice director and a fellow at Avanade Inc., an integrator for Microsoft technology that's a joint venture between Accenture Ltd. and Microsoft Corp. Craig Nelson is a systems engineer at Avanade. Readers can send comments or questions to Burry at Christopher.Burry@avanade.com.

Nevertheless, the long-term advantages of server virtualization outweigh the short-term costs. Where should you start?
In a past column, we discussed the topic of server consolidation. Clearly, server virtualization is ripe for the consolidation market. Many organizations operate with a "one server, one application" mind-set. As processors evolve and add new technologies (such as hyper-threading and 64-bit computing), this is often wasteful -- and will ultimately lead to unnecessary expense.
Where else does server virtualization fit into your IT plans? For 2004, Gartner