Server virtualization is the ability for a single system to host multiple guest operating system sessions, effectively taking advantage of the processing capabilities of a very powerful server. Most servers in data centers run under 5%--10% processor utilization, meaning that there is excess capacity on the servers that is unused. By combining the capabilities of multiple servers, an organization can better utilize the processing power available in the networking environment.
Some might suggest that an organization should just put more users on existing server systems to take advantage of the excess server capacity. However from a load-balancing perspective, most organizations prefer to not combine more users on a single system, but rather have multiple systems distributing the workload to provide some level of distributed processing. This also minimizes single points of failure for an organization and provides distribution of processing across multiple systems. Server virtualization can provide server consolidation while still providing multiple physical host systems to distribute the processing load.
History of Windows Virtualization
Microsoft's position in the virtualization marketplace prior to the release of Windows 2008 wasn't one where Microsoft particularly had a bad product, it was because Microsoft jumped into the virtualization space just 4 to 5 years before the release of Windows 2008 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 allows 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.
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.
Prior to 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, memory allocation, and system resources. 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 like VMware ESX as well as Hyper-V leverage a hypervisor-based technology that allows the guest operating systems to effectively bypass the host operating system and communicate directly with system resources. In some instances, the hypervisor will manage shared guest session resources, and in other cases will pass guest session requests directly to the hardware layer of the system. By providing 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 are available with and without Hyper-V, so from product launch in February 2008, Windows 2008 is ready to be a virtual server host system.
What's New in Hyper-V
There are many long-awaited features and technologies built in to Hyper-V that provide Microsoft the ability to compete with other server virtualization products on the market. Some of the key additions to Hyper-V include the following:
- Support for x64-bit guest sessions -- Finally, Microsoft supports 64-bit guest sessions with Hyper-V. On a Windows 2008 server running Hyper-V, the system can host 32-bit and 64-bit guest sessions. .
- Support for greater guest session memory -- Windows 2008 virtualization supports guest session memory allocation greater than 32GB of memory per session. .
- Support for up to four cores per guest session -- Windows 2008 virtualization provides the capability to have up to four core processors allocated to a single guest session, providing individualized guest session performance enhancements.
Microsoft Hyper-V Server as a Role in Windows Server 2008
As much as Windows 2008 x64-bit has the hypervisor built in to the core operating system, Microsoft has chosen to release the virtual server capability as a separate download. As a download, the virtual server installation option will be enabled as a server role just as Windows 2008 Terminal Services, Network Access Protection, or SharePoint services are added to the server as a separate server role.
The installation of the Microsoft Hyper-V Server role is covered later in this chapter in the section "Installation of the Microsoft Hyper-V Server Role."
Use the following table of contents to navigate to chapter excerpts
|ABOUT THE BOOK:|
|Windows Server 2008 Unleashed covers the planning, design, prototype testing, implementation, migration, administration and support of a Windows 2008 and Active Directory environment, based on more than three and a half years of early-adopter experience in full production environments. This book addresses not only what is new in Windows 2008 compared with previous versions of the Windows Server product, but also what is different and how the similarities and differences affect an organization's migration to Windows 2008. Chapters are dedicated to the migration process from Windows 2000/2003 to Windows 2008, how to properly use Group Policies in Windows 2008, and tips and tricks on managing and administering a Windows 2008 environment. Purchase the book from InformIT.|
|ABOUT THE AUTHORS:|
|Rand Morimoto has been in the computer industry for more than 30 years and has authored, co-authored or been a contributing writer for dozens of bestselling books on Windows 2003, Exchange 2007, security, BizTalk Server, and remote and mobile computing. Michael Noel has been involved in the computer industry for nearly two decades and has significant real-world experience with enterprise information technology environments. Michael has authored several major publications, such as SharePoint 2007 Unleashed and Exchange 2007 Unleashed Omar Droubi has been in the computer industry for more than 15 years, has co-authored one of Sams Publishing's bestselling books, Windows 2003 Unleashed, and has been a contributing writer and technical reviewer on several other books on Windows Server 2003 as well as Exchange 2000, 2003 and 2007. Ross Mistry is a seasoned veteran in Silicon Valley and has spent more than a decade in the computer industry. As a principal consultant and partner with Convergent Computing (CCO), he had the opportunity to work with Windows Server 2008 for three years before the product was released to the public. Chris Amaris is the chief technology officer and co-founder of CCO. He has more than 20 years' experience consulting for Fortune 500 companies, leading them in the selection, design, planning and implementation of complex information technology projects. Chris worked with Windows 2008 for three years before its release to the general public.|