While EMC subsidiary VMware has garnered the bulk of attention regarding server virtualization, a slew of vendors are looking to address what they see as rising demand for this server consolidation technique.

At the top of that list is Microsoft, which several months ago aired plans for Virtual Server 2005. Like other server virtualization technologies, Virtual Server 2005 lets users divvy up servers so that they can support multiple operating system instances and applications. The software, scheduled to ship next year, is based on technology obtained via the acquisition of Connectix early last year that works on Windows, Linux and Macintosh servers and workstations.

Also entering the market are a gaggle of lesser-known players, such as Leostream and PlateSpin, whose products offer management, security and other such capabilities for virtualized systems.

"Virtualization is moving from a niche market into the mainstream, especially since Microsoft entered the market," says David Crosbie, CEO of Leostream, whose software manages virtualization servers attached to storage-area networks (SAN).

But it is VMware, which EMC paid US$635 million to acquire earlier this year, that sparked the server virtualization movement. Recently, the EMC subsidiary held its first annual customer conference, where VMware and others announced the latest developments in server virtualization.

VMware announced that it would extend the capabilities of its Virtual SMP offering to dual-core and four-processor symmetrical multiprocessing servers. The company, which already offers dual-processor SMP software, is doing this for two reasons. First, VMware officials say that even though most server workloads run fine on two-processor servers, 15 percent to 20 percent of customers require machines with four processors. Also, VMware is trying to keep pace with next-generation servers powered by Advanced Micro Devices (AMD) and Intel processors.

"If you look at processor trends, both Intel and AMD have shifted from increasing the clock speed of their processors to increasing the number of processor cores on a single chip," says Michael Mullaney, vice president of marketing for VMware. "Going forward, you are going to find out that even a two-CPU server actually has four processors."

VMware, which was founded in 1998, has partnerships with Citrix Systems, Dell, Hewlett-Packard, IBM, Oracle and Red Hat, among others. Gartner says VMware owns the bulk of the virtualized server market and will control about 80 percent of it by the end of next year, though the research firm figures Microsoft will start to challenge VMware over the next couple of years.

Here's a look at some of the other companies vying for attention in server virtualization:

Leostream, a VMware partner, started in 2001 and makes the Virtual Machine Controller (VMC). The software is designed for managing server virtualization products from VMware and Microsoft, presenting each virtual server on a Web-based display. Its latest offering, VMC SAN edition, is for managing virtualized servers attached to a SAN. It costs US$2,800, plus US$300 per processor managed.

"One of the biggest features of Leostream's VMC SAN Edition is the ability for your virtual machines to fail over," says Leo Frisino, computer systems programmer for the New York State Division of Housing and Community Renewal. "If a virtual machine is executing in a server and that box fails, the virtual machines will come up on the other ESX box. VMware does not have similar failover capability," says Frisino, who virtualizes five production servers with VMware's ESX Server.

PlateSpin recently launched software that lets IT automatically convert Windows and Linux servers back and forth from physical servers to virtualized servers. PlateSpin's PowerP2V 3.6, which runs on a desktop PC, starts at US$3,000 for a version that allows 25 conversions.

Softricity partnered with Aurema to let customers manage, streamline and optimize their virtual machine environments running VMware's ESX Server and Citrix MetaFrame. Softricity's software enables applications to be spread across virtual machines, while Aurema's ArmTech is workload management software that monitors, optimizes and dynamically allocates processors and memory for applications running in virtual machine environments.

Dave Williams, senior systems engineer for the Government Employees Hospital Association, uses ArmTech on his servers to balance application loads. "Once our Citrix servers were rebooting, locking up and had the processors running to 100 percent," he says. "ArmTech balances the workload of applications with the (server's) memory and processor, so one user can't steal 100 percent of the processing capability."