1. Guest OS Licenses—One of the most important differences to note between Hyper-V Server 2012 and Windows Server 2012 Hyper-V is the fact that Hyper-V Server 2012 doesn't include any guest OS licenses. (For more information about Windows Server 2012 licensing, see the Windows Server 2012 Volume Licensing Buyer's Guide.) Hyper-V Server 2012 is a great option when you want to run Linux or for virtual desktop infrastructure (VDI) scenarios in which the licensing advantages of the Windows Server 2012 Standard and Datacenter editions don't apply.
2. Host Scalability—Hyper-V Server 2012 provides the same scalability that you can get from Windows Server 2012 Hyper-V. Hyper-V Server 2012 supports 320 logical host processors, 4TB of host RAM, 2,048 virtual CPUs per host, and 1,024 active virtual machines (VMs) per host.
3. Guest Scalability—The free Hyper-V Server 2012 supports the same high levels of guest scalability that are found in Windows Server 2012 Hyper-V. Hyper-V Server 2012 provides support for 64 virtual CPUs per VM, support for guest Non-Uniform Memory Access (NUMA), and support for up to 1TB of RAM per VM.
4. Cluster Support—Hyper-V Server 2012 systems can fully participate in Microsoft Windows failover clusters. There's full support for up to 64-cluster nodes and up to 8,000 VMs.
5. Storage Capabilities—Hyper-V Server 2012 shares most of the new Windows Server 2012 storage enhancements. Hyper-V Server 2012 supports up to four virtual Fibre Channel adapters per VM. Hyper-V Server 2012 also supports the new VHDX format with up to 16TB virtual hard disks. In addition, Hyper-V Server 2012 provides Offload Data Transfer (ODX) support for high-performance SAN data transfers and Windows Server 2012 Storage Spaces.
6. Advanced Networking—Microsoft introduced NIC teaming using heterogeneous network adapters in Windows Server 2012. Hyper-V Server 2012 inherits the same NIC teaming ability, which you can configure with the Hyper-V PowerShell cmdlets. Hyper-V Server 2012 also supports single root I/O virtualization (SR-IOV). For high-performance VM networking, HyperV Server 2012 supports quality of service (QoS), providing the ability to specify the minimum bandwidth available to a VM or a port.
7. Dynamic Memory—Hyper-V Dynamic Memory was first introduced with Windows Server 2008 R2 SP1. Dynamic memory increases the server consolidation ratio that are possible. Hyper-V Server 2012 fully supports memory overcommit. However, like Windows Server 2012 Hyper-V, the guest OS must support hot-add RAM in order to take advantage of dynamic memory.
8. VM Mobility—Microsoft first introduced live migration in Windows Server 2008 R2 and significantly enhanced this feature in Windows Server 2012. Hyper-V Server 2012 supports all of the live migration options that are provided in the full Windows Server 2012 Hyper-V implementation. Hyper-V Server 2012 supports Shared Storage Live Migration, Server Message Block (SMB) Live Migration, Shared-Nothing Live Migration, and Storage Live Migration. Multiple concurrent live migrations are supported and all can be run with no end-user downtime. There is also full support for Hyper-V Replica.
9. Hyper-V Extensible Switch—The new Hyper-V Extensible Switch is fully supported in Hyper-V Server 2012. The Hyper-V Extensible Switch supports internal, external, and private switches. There's also support for Private VLANs (PVLANs) and DHCP Guard. Like Windows Server 2012 Hyper-V, Hyper-V Server 2012 is fully extensible and supports multiple filter extensions, capture extensions, and forwarding extensions.
10. Network Virtualization—Microsoft first introduced network virtualization in Windows Server 2012; this feature allows you to extend your networks across different subnets and from your on-premises networks into the cloud. Network virtualization enables you to seamlessly move VMs from on-premises into the cloud and back, with no downtime and no need to change the VM or application's networking.