Virtualization is the means by which you can isolate one computing resource from another. In a traditional software stack, each resource is linked with the other. For example, a traditional application usually runs on specific hardware, physically tying the application to the resources that make it operate.

Network resources are tied to specific locations; storage is tied to specific containers; operating systems are assigned to specific hardware; network interfaces are bound to specific processes; and applications are installed on specific hardware and run on a specific operating system.

When you virtualize various components in the datacenter, you release them from these traditional bindings. Because of this, virtualized components often result in more efficient resource utilization, provide greater flexibility of operation, and simplify change management:

• You can virtualize networks to localize dispersed resources.
• You can virtualize storage to bring together various distributed containers into one single view.
• You can virtualize machines to run any operating system.
• You can virtualize presentation services to provide access to them from any connected location.
• You can virtualize applications to support computing on demand models.
• You can virtualize user profiles to give them access to their data from any location.

These various layers of virtualization can work together to create a completely dynamic datacenter—one where IT can respond rapidly and efficiently to the changing needs of the organization it supports.

Microsoft products are designed to work together to provide support for each layer of the virtualization stack. In fact, Microsoft provides a complete stack of products in support of virtualization in datacenters of all sizes. Table below outlines each product and its target virtualization layer.

Product	Purpose
Windows Server 2008	Supports the Hyper-V role. Supports traditional network workloads in virtual machines. Supports virtual networking.
Windows Storage Server	Supports network-attached storage (NAS).
Windows Unified Data Storage Server	Supports NAS. Acts as a front end for storage area networks. Supports virtual hard disks (VHDs) as iSCSI targets.
System Center Data Protection Manager	Provides disk-to-disk backups. Provides remote-site backups. Backs up physical and virtual machines.
Windows Hyper-V Server	A free download that supports the Hyper-V role in a stand-alone configuration only.
Microsoft Virtual Server	Supports server-based virtual machine operation but requires an existing operating system.
Virtual PC	Supports desktop-based virtual machine operation but requires an existing operating system.
Microsoft Enterprise Desktop Virtualization (MED-V)	Supports centralized virtual machine image management. Supports virtual machine life-cycle management. Supports the application of usage policies for desktop virtual machines as well as data control policies. Publishes applications inside virtual machines seamlessly to the user’s desktop. Requires Virtual PC to run.
Virtual Desktop Infrastructure (VDI) and Vista Enterprise Centralized Desktop (VECD)	Runs end-user desktops in centralized virtual machines using the Hyper-V server-based virtual machine engine. Relies on VECD for Windows Vista or downgraded operating system licensing of centralized desktop virtual machines.
Windows Server 2008 Terminal Services	Provides next-generation presentation virtualization services through server-based computing.
Microsoft Application Virtualization (App-V)	Supports application virtualization, transforming applications into centrally managed virtual services that are never installed and don’t conflict with other applications. Supports application streaming and local application caching as a delivery mechanism.
Windows Server 2008 with Active Directory	Supports profile virtualization through a combination of Group Policy Objects (GPOs) running Folder Redirection and the Roaming Profile.
System Center Virtual Machine Manager	Supports centralized management of server-based virtual machine engines such as Hyper-V and Virtual Server. Supports virtual machine libraries. Provides self-service virtual machine provisioning. Provides physical-to-virtual and virtual-to-virtual machine conversion.
System Center Operations Manager	Supports monitoring and proactive rehabilitation of both physical and virtual machines.
System Center Configuration Manager	Supports inventorying and configuration management for both physical and virtual machines. Supports virtualized application deployment.

The products listed in Table above list the entire software stack Microsoft provides in support of virtualization. However, the virtualization industry moves at such a pace that it is very likely that new products will be made available by the time you read this.

In fact, IDC, an international research firm, estimates that only 17 percent of the worldwide server market will be virtualized by 2010, compared to 5 percent in 2005 (Information Week, October 2007). This leaves a lot of room for the market to grow over the next few years.