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Server room menu: Server virtualization in four styles

Virtualization is set to cut a large swath of headlines this year, but users would be wise to understand each virtualization style in turn before taking the plunge into a virtual server world.

By all reports -- from tea leaves to star charts -- server virtualization on x86 architecture will become one of the most disruptive technologies to storm the data center this year.

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However, any user entertaining the idea of moving servers into a virtual world are best served by avoiding the urge to get caught up in the hype that will inevitably arrive throughout 2006. Instead, analysts advise that a critical evaluation of resources and an ironclad grip on understanding the behavior of the server workloads and styles is necessary before they even utter the word virtualization.

"Virtualization is fundamentally sharing resources; it is changing the way resources are allocated and if customers are not careful, they can get performance issues," said Rye Brook, N.Y.-based Ideas International Ltd. analyst Tony Iams. "Make you're your servers are overrutilized before going to virtual machines."

Without further ado, here are today's virtualization choices:

VMware: GSX Server and ESX Server

The fundamental problem addressed by virtualization is running multiple operating systems at the same the time on the one server. The problem was decades ago on the mainframe, but it was only within the past few years that market leader VMware Inc. was able to accomplish a working model with x86 architecture.

"VMware is really the company that got the interest in virtualization started," said Ideas International's Iams. "The whole reason we're talking about it today is that [VMware was] able to change the rules of the game and bring virtual machine capabilities to the Intel platform."

Price had been a stigma attached to VMware, but the company had effectively neutralized that criticism with the release of a free version of its GSX Server in February. GSX works by letting multiple operating systems run on top of it as a host, thereby linking them as a virtual whole.

VMware ESX Server is not free, but Iams said that for customers who use that application, price is a non-issue. "In the grand scheme of things, pricing isn't too critical because for people going with a virtualization application, the quality of the implementation is the most critical component."

While the free GSX offering is representative of VMware's awareness that XenSource Inc. and Microsoft are now competitors, Iams said that free (Xen) or competitively priced (Virtual Server) products are only a door-opener. "Strategically, users remain willing to pay for an application that has been proven to handle today's high production server workloads."

Goes best with: Customers who want to virtualize heterogeneous workloads and who also require mature virtualization management tools.

IBM: IBM Advanced POWER Virtualization

Today, Big Blue finds itself in the middle of a fairly substantial, multi-year endeavor to turn the POWER family of processors into an alternative that can attack the virtualization market on multiple levels.

In the past, IBM created such applications as part of an effort to compete with high-end rivals Sun Microsystems Inc. and chip maker Intel Corp. Today, however, IBM has shifted gears so that it can also address x86 chips like Intel's Pentium and Advanced Micro Devices' (AMD) Opteron.

To Nashua, N.H.-based Illuminata Inc. senior analyst Gordon Haff, the effort has paid off in a fairly advanced product, in part because of IBM's experience in hardware and software.

"IBM Advanced POWER Virtualization is obviously specific to POWER -- just as IBM mainframe virtualization is specific to zSeries because being able to develop hardware and software in concert has advantages.

Historically, Haff said, IBM's POWER Virtualization came from "logical partitioning" LPARs technology, which is a bit different from virtual machines. But the two categories have approached such closeness that it's no longer a meaningful distinction.

Goes best with: Customers who want to virtualize their Unix workloads.

Microsoft: Virtual PC and Virtual Server 2005

As the number two player in the virtualization space, Microsoft has recognized the success of VMware and the inevitable trend toward more virtualization in the data center.

Microsoft acquired Virtual PC in 2003 to kickstart its presence in virtualization. Today, the support for Virtual PC has been extended to Virtual Server 2005, a product which Iams believed has attained some of the value of VMware's products -- but not all of it.

"Microsoft does not have any equivalent to [VMware] ESX and will not have that capability for a few years, but it does have a similar [hypervisor-like] offering to the GSX server," Iams said.

Virtual Server 2005 is a relatively new product, but is still a key component of Microsoft's autonomic computing plan, called the Dynamic Systems Initiative. It requires a host -- Windows Server 2003 -- and exchanges performance for installation and broad hardware support. It is the young age of the product that allows Microsoft to market and price it aggressively against VMware GSX, Iams said.

The aggressive pricing only carries Virtual Server 2005 to a point, however, and then the charges for the server, storage, host and guest OS, middleware and applications begin to chip away at that advantage.

Goes best with: Customers who want to virtualize primarily Windows workloads.

XenSource – XenOptimizer

The fact that a significant player like VMware decided to give away one of its core applications for free is a testament to the influence of Xen virtualization and the open source community model.

VMware is still the technology leader in virtualization, and it has a substantial lead in maturity over XenSource -- the brainchild of a handful of Xen developers. But many industry experts see Xen coming on strong as Red Hat Inc. and Novell Inc. build support for the technology into their Linux distributions.

XenOptimizer automates the transformation from physical to virtual servers on Linux. It provides a dashboard for monitoring computing resources and allows drag-and-drop provisioning of virtual machines. It is this functionality that many believe will bring a much wider audience to Xen than just experts and enthusiasts.

"[Xen] is still in the realm of the startups and systems providers contributing technology, like the Linux distros, and it is late to the gate as it were. But by bringing in open source, there's a lot of interest in that," Iams said.

Xen was also given a boost recently with the release of Xen 3.0, the first update to the technology in over a year. The version supports Intel's hardware-based virtualization technology, Intel-VT, which will be a significant key in overcoming Xen's current inability to virtualize Windows.

Xen 3.0 will be distributed in Red Hat Enterprise Linux 5 and Novell and Novell SuSE Linux Enterprise Server 10 later this year. XenOptimizer is available in beta form, and product availability is scheduled for early 2006.

Goes best with:Customers who virtualize Linux workloads, but there's no Windows support yet.

There are more virtualization options out there, so send me your thoughts at Jack Loftus, News Writer.

This article originally appeared on

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