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Understanding Microsoft's Virtualization Strategy

Microsoft jumped into the virtualization market several years behind its competitors. Being relatively new to the virtualization space, Microsoft had some catching up to do.

Acquisition of Virtual PC

Microsoft jumped into the virtualization market through the acquisition of a company called Connectix in 2003. At the time of the acquisition, Virtual PC provided a virtual session of Windows on either a Windows system or on a Macintosh computer system. Virtual PC was used largely by organizations testing server software or performing demos of Windows systems on desktop and laptop systems. Virtual PC for the Mac enabled Macintosh users to run Windows on their Macintosh computers.

Microsoft later dropped the development of Virtual PC for the Mac. However, they continued to develop virtualization for Windows systems with the release of Virtual PC 2007. Virtual PC 2007 enables users running Windows XP or Windows Vista to install, configure, and run virtual guest sessions of Windows Server or even non-Windows operating systems.

Microsoft Virtual Server

Virtual PC is targeted at those operating under an operating system that is typically optimized for personal or individual applications. It does not scale for a data center wanting to run four, eight, or more sessions on a single system. At the time of the acquisition of Connectix, Connectix was developing a virtual server solution to allow for the operation of virtualization technologies on a Windows 2003 host server system.

Because a Windows Server 2003 system provides more RAM availability, supports multiple processors, and generally has more capacity and capabilities than a desktop client system, Microsoft Virtual Server provided organizations with more capabilities for server-based virtualization in a production environment.

Virtual Server 2005

Although the initial Virtual Server acquired through the Connectix acquisition provided basic server virtualization capabilities, it wasn't until Virtual Server 2005 that Microsoft had its first internally developed product. Virtual Server 2005 provided better support and integration into a Windows 2003 environment, better support for multiprocessor systems and systems with more RAM, and better integration and support with other Microsoft server products.

In just two years, Microsoft went from having no virtual server technologies to a second-generation virtual server product; however, even with Virtual Server 2005, Microsoft was still far behind its competitors.

Virtual Server 2005 R2

Over the subsequent two years, Microsoft released two major updates to Virtual Server 2005 with the release of an R2 edition of the Virtual Server 2005 product and a service pack for the R2 edition. Virtual Server 2005 R2 Service Pack 1 provides the following capabilities:

  • Virtual Server host clustering—This technology allows an organization to cluster host systems to one another, thus allowing guest sessions to have higher redundancy and reliability.
  • x64 host support—x64 host support means that organizations had the capability to use the 64-bit version of Windows 2003 as the host operating system, thus providing better support for more memory and system capacity found in x64-bit systems. Guest operating systems, however, are still limited to x86 platforms.
  • Hardware-assisted virtualization—New to processors released from Intel (Intel VT) and AMD (AMD-V) are processors that provide better distribution of processor resources to virtual guest sessions.
  • iSCSI support—This technology allows virtual guest sessions to connect to iSCSI storage systems, thus providing better storage management and storage access for the guest sessions running on a virtual server host.
  • Support for more than 16GB virtual disk sizes—Virtual disk sizes can reach 2TB in size, thus enabling organizations to have guest sessions with extremely large storage capacity.

These capabilities—among other capabilities of the latest Virtual Server 2005 product—brought Microsoft closer to its competition in the area of server virtualization.

Integration of Hypervisor Technology in Windows Server 2008

To leap beyond its competition in the area of server virtualization, Microsoft had to make some significant changes to the operating system that hosted its next-generation virtual server technology. With Windows 2008 in development, Microsoft took the opportunity to add in a core technology to Windows 2008 that provided the basis of Microsoft's future dominance in server virtualization. The core technology is called hypervisor, which effectively is a layer within the host operating system that provides better support for guest operating systems. Microsoft calls their hypervisor-based technology Hyper-V.

Before the inclusion of Hyper-V in Windows 2008, the Virtual Server application sat on top of the host operating system and effectively required all guest operating systems to share system resources, such as network communications, video-processing capabilities, and memory allocation. In the event that the host operating system has a system failure of something like the host network adapter driver, all guest sessions fail to communicate on the network. This monolithic approach is similar to how most server virtualization technologies operate.

Technologies such as VMware ESX and Hyper-V leverage a hypervisor-based technology that allows the guest operating systems to effectively communicate directly with system resources without having to pass through the host operating system. In some instances, the hypervisor manages shared guest session resources, and in other cases passes guest session requests directly to the hardware layer of the system. By ensuring better independence of systems' communications, the hypervisor-supported environment provides organizations better scalability, better performance, and ultimately, better reliability of the core virtual host environment.

Hyper-V is available in Windows 2008 Standard, Enterprise, and Datacenter editions. Each of these SKUs is available with and without Hyper-V; so from product launch in February 2008, Windows 2008 has been ready to be a virtual server host system.

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