Hyper-V implementations

Windows Server 2012 R2 includes the Hyper-V role only in the Standard and Datacenter editions. The Hyper-V role is required for the OS to function as a computer’s primary partition, enabling it to host other VMs. No special software is required for an OS to function as a guest OS in a VM. Therefore, although Windows Server 2012 R2 Essentials does not include the Hyper-V role, it can function as a guest OS. Other guest OSs supported by Hyper-V include the current Windows workstation OSs and many other non-Microsoft server and workstation products.

Hyper-V licensing
The primary difference between the Standard and Datacenter editions of Windows Server 2012 R2 is the number of VMs they support. When you install a Windows Server 2012 R2 instance on a VM, you must have a license for it, just like when you install it on a physical machine. Purchasing the Datacenter edition allows you to license an unlimited number of VMs running Windows Server 2012 R2 on that one physical machine. The Standard license allows you to license only two virtual instances of Windows Server 2012 R2.

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Note: READERAID HEADER
Readeraid. You might find that reports vary on the specific minimum requirements of Windows Server 2008. This is not uncommon for new operating systems because the minimum requirements change as the operating system moves from beta to the release candidate stage to the final RTM version. The requirements outlined in Table 1-1 are not finalized. You might be able to get Windows Server 2008 to install on a computer that does not meet these specifications, but the experience will be less than optimal.

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Hyper-V hardware limitations
The Windows Server 2012 R2 version of Hyper-V contains massive improvements in the scalability of the system over previous versions. A Windows Server 2012 R2 Hyper-V host system can have up to 320 logical processors, supporting up to 2,048 virtual CPUs and up to 4 terabytes (TB) of physical memory.
One server can host as many as 1,024 active VMs and a single VM can have up to 64 virtual CPUs and up to 1 TB of memory.
Hyper-V can also support clusters with up to 64 nodes and 8,000 VMs.

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NOTE: WINDOWS POWERSHELL
Another major improvement in the Windows Server 2012 and Windows Server 2012 R2 versions of Hyper-V is the inclusion of a Hyper-V module for Windows PowerShell, which includes new cmdlets dedicated to the creation and management of the Hyper-V service and its VMs.

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Hyper-V Server
In addition to the Hyper-V implementation in Windows Server 2012 R2, Microsoft provides a dedicated Hyper-V Server product, which is a subset of Windows Server 2012 R2.
Hyper-V Server 2012 R2 includes the Hyper-V role, which it installs by default during the OS installation. With the exception of some limited File and Storage Services and Remote Desktop capabilities, the OS includes no other roles, as shown in Figure 3-3.

FIGURE 3-3 Roles available in Hyper-V Server

The Hyper-V Server is also limited to the Server Core interface, althoughas with all Server Core installations it includes SCONFIG, a simple, script-based configuration interface, as shown in Figure 3-4. You can manage Hyper-V Server remotely by using Server Manager and Hyper-V Manager, just as you would any other Server Core installation.

FIGURE 3-4 The Server Core interface in Hyper-V Server

Unlike Windows Server 2012 R2, Hyper-V Server is a free product, available for download from Microsoft’s website. However, Hyper-V Server does not include any licenses for virtual instances. You must obtain and license all the OSs you install on the VMs you create.