What's New in Windows 8 for Hyper-V Based Cloud Computing (Part 1) - Hyper-V Key Features

by [Published on 18 Oct. 2011 / Last Updated on 18 Oct. 2011]

In this article, you will learn about new key Hyper-V features in Windows Server 8.

If you would like to read the other parts in this article series please go to:

This article is the first of an 11 part series that provides a comprehensive look at the new features in Windows Server 8 and Client that support virtualization and cloud computing.

The Multi-Tenant Cloud

At the Microsoft Build conference held September 13 – 16, 2011 in Anaheim, Microsoft provided a first look at Windows Server 8 features, including Hyper-V, which will enable organizations to support Infrastructure as a Service (IaaS) deployments using public, private and hybrid, multi-tenant cloud architectures. A multi-tenant cloud is a cloud infrastructure that is capable of hosting services (workloads) for multiple, distinct organizations (i.e., distinct departments within a single company in a private cloud, or distinct companies in a public cloud) while maintaining secure workload isolation amongst the various tenants. In addition, a multi-tenant cloud infrastructure is capable of dynamically placing and redistributing tenant workloads on any available host in the cloud without compromising the secure workload isolation. Finally, the multi-tenant cloud infrastructure must be able to provide and guarantee distinct Service Level Agreements (SLAs) that are based on organizational requirements, and provide resource metering that allows proper chargeback for the use of cloud resources to each organization. In order to enable multi-tenant cloud infrastructures, Windows Server 8 includes a slew of new features that span Hyper-V, storage, network, high-availability, disaster recovery, and manageability.

Hyper-V Core Features in Windows Server 8

In Windows Server 8, Hyper-V features are enhanced, improving virtual machine performance and providing a scalable virtualization base for cloud deployments. Table 1 provides a comparison of Hyper-V key features between Windows Server 2008 R2 and Windows Server 8.

Hyper-V Features

Windows Server 2008 R2

Windows Server 8

Host Memory

1 TB

2 TB

Logical Processors

64 (Max)

160 (Max)

Guest VM Memory

64 GB (Max)

512 GB (Max)

Guest Virtual Processors

4 per VM (Max)

32 per VM (Max)

Guest NUMA



Host Failover Cluster

Y (16 nodes)

Y (63 nodes)

VM Support - Failover Cluster

1000 (Max)

4000 (Max)

Live Migration

Y (serial)

Y (concurrent)

Live Migration (no cluster or shared storage)



Live Storage Migration



Table 1: Hyper-V Feature Comparison

Hyper-V now supports 2 TB of physical memory and a maximum of 160 logical processors. In Hyper-V, it is not only cores that are included in the logical processor count, so are threads if a core is Simultaneous Multi-Threading (SMT) enabled. Therefore, the following formula is handy to calculate the number of logical processors that Hyper-V can see on a given physical server:

# of Logical Processors = (# of Physical Processors) * (# of Cores) * (# of Threads per Core)

The increase in memory and logical processor support in Windows Server 8 provides the basis upon which to build dense virtual machine populations for private and public cloud infrastructures. In addition, Hyper-V in Windows Server 8 supports enhanced virtual machine performance by enabling the assignment of up to 512 GB of RAM and 32 virtual processors to a virtual machine. That can easily accommodate scale up of high-performing workloads especially coupled with intelligent resource management features like dynamic memory, and new networking and storage management features that you will discover later in this article.

For systems and applications that are built on top of a non-uniform memory access (NUMA) architecture, Windows Server 8 provides guest NUMA. Guest NUMA means that Hyper-V ensures guest virtual machine processor and memory affinity with physical host resources.

Another upgraded feature in Windows Server 8 is the expansion of failover clusters to 63 nodes (from 16 nodes in Windows Server 2008 R2), effectively quadrupling the size of a cluster and the number of running virtual machines to 4000 (from 1000 in Windows Server 2008 R2) per cluster.

With Windows Server 8, Hyper-V also supports multiple, concurrent live migrations of virtual machines. The number of concurrent live migrations is bounded only by the inherent resource constraints of the infrastructure rather than the serial limitation imposed in Hyper-V on Windows Server 2008 R2.

And while Live Migration has been a cluster-centric feature requiring shared storage, the story gets significantly better in Windows Server 8 with the support for live migration of a virtual machine between any two hosts without requiring clustering, shared storage, or any shared resources other than a network connection. You can control which Hyper-V hosts participate in this Live Migration mode, as well as the number of concurrent live migrations allowed by a host, and the network to use to perform the live migration. Furthermore, there is additional granularity in the selection of virtual machine components to migrate, allowing you to choose all components, including the VHD files, current configuration, snapshots, and second level paging, or only some of these components. You also have the ability to move the virtual machine data to a single location, or to specify individual locations for every selected virtual machine component.

As if all this goodness wasn’t enough, Hyper-V also provides Live Storage Migration that supports moving virtual machine storage resources between physical storage units without service interruption.

Hyper-V Key Storage Features in Windows Server 8

One of the main new Hyper-V storage features is the addition of a virtual Fibre Channel HBA adapter for virtual machines. This allows a virtual machine to connect to a Fibre Channel SAN, and enables new scenarios like guest clustering, use of MPIO, and other multipathing solutions for workloads that require high-performing SAN and application availability. This feature is available to existing Windows virtual machines like Windows Server 2008 R2 running on Hyper-V on Windows Server 8.

Another new storage feature is the VHDX format, a new virtual hard disk (VHD) format that is introduced in Windows Server 8. With VHDX, the maximum size of a VHD increases to 16 TB, instead of the current 2 TB limit with the current VHD format which forces the use of pass-through disks to meet larger virtual disk storage requirements. The VDHX format also provides large sector support, and allows embedding user-defined metadata.

Along with the increase in virtual disk size is an impressive performance boost when creating or managing large VHDX-based formats using the Offloaded Data Transfer (ODX) features of storage systems. Hyper-V support for ODX in Windows Server 8 allows handing off operations like data transfers and file creations to the storage system which can perform the actions with much higher performance while reducing the impact of associated operations on the Hyper-V host processor.

Hyper-V Key Network Features in Windows Server 8

On the networking side, one the of the key Hyper-V features in Windows Server 8 is the extensible Hyper-V switch. The Hyper-V switch is the component that controls the configuration and creation of external, internal, and private networks that support virtual machine connectivity to physical networks, to other virtual machines and the Hyper-V host, or to a subset of virtual machines, respectively. In Windows Server 2008 R2, the Hyper-V switch functionality cannot be modified. In Windows Server 8, an API exists that enables extension of the Hyper-V switch functionality. Microsoft’s goal is to enable security vendors to develop new security appliances as pluggable switch modules, enable switch vendors to create switch extensions that unify virtual and physical switch management, and enable network application vendors to create network monitoring extensions for the Hyper-V switch. Taking advantage of the Hyper-V switch extensibility, Cisco Systems has already announced support for Windows Server 8 Hyper-V with its Cisco Nexus 1000V switch.

Probably one of the most requested networking features included in Windows Server 8 and supported by Hyper-V is NIC teaming. Up through Windows Server 2008 R2, NIC teaming has only been available as a third-party option. Windows Server 8 provides native NIC teaming that is configurable at the host (parent partition) or virtual machine (guest partition) level in either load balancing or failover mode. As a bonus, this new NIC teaming feature even works across different vendor network adapters.


In this article, you learned about some key features introduced in Windows Server 8 that are supported by Hyper-V. However, they represent only a drop in the ocean of new capabilities and functionality that Microsoft has built into Windows Server 8 to make it a robust, high-performance, and flexible base upon which to build scalable cloud infrastructures. In Part 2 of this series, you will learn about the Hyper-V features in Windows 8 Client. In upcoming articles in this series, you will learn about the cloud scenarios that Microsoft supports with Windows Server 8, before learning in detail about the range of new storage, networking, and management features that Microsoft is betting on to make Windows Server 8 the preeminent virtualization and cloud platform.

If you would like to read the other parts in this article series please go to:

Featured Links