History of Windows Virtualization

Microsoft’s position in the virtualization marketplace prior to the release of Windows 2008 R2 wasn’t one where Microsoft particularly had a bad product; it was because Microsoft jumped into the virtualization space just four to five years before the release of Windows 2008 R2 virtualization. Being relatively new to the virtualization space, Microsoft had some catching up to do.


Acquisition of Virtual PC
Microsoft jumped into the virtualization marketplace 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—or in the case of Virtual PC for the Mac, the ability for a Macintosh user to run Windows on their Macintosh computer. Microsoft later dropped the development of Virtual PC for the Mac; however, it continues 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, however, is targeted at operating under an operating system that is typically optimized for personal or individual applications, so Virtual PC 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 in development of a virtual server solution that allows 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 very 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 provided 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 allowing organizations the ability 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.

Source of Information : Sams - Windows Server 2008 R2 Unleashed