What's new in Windows Server 2008 R2 Hyper-V

by [Published on 8 Sept. 2009 / Last Updated on 8 Sept. 2009]

Looking at the latest features included in Windows Server 2008 R2 Hyper-V.

Introduction

In this article, you will learn about the new features that are included in Windows Server 2008 R2 Hyper-V. Although, the Live Migration feature is probably the most anticipated new Hyper-V feature, there are many other improvements geared towards expanding Hyper-V functionality in the areas of performance, networking, and dynamic configuration.

Core Features of Microsoft Windows Server 2008 R2 Hyper-V

In the table below, you can see a list of the core features in Windows Server 2008 R2 Hyper-V and Microsoft Hyper-V Server 2008 R2. One of the evolutionary changes is the support for up to 64 processor cores to accommodate servers with eight eight-core physical processors. If you recall, Windows Server 2008 Hyper-V supports a maximum of 16 cores (out of the box) and 24 cores with the installation of KB 956710.

 

Windows
Server 2008 R2 Standard

Windows Server 2008 R2 Enterprise

Windows Server 2008 R2 Datacenter

Microsoft Hyper-V

Server 2008 R2

x86 Support

Guest OS Only

Guest OS Only

Guest OS Only

Guest OS Only

x64 Support

Host and Guest

Host and Guest

Host and Guest

Host and Guest

# of VMs—x64 Host

192 (Max)

384 (Max)

384 (Max)

384 (Max)

Host Memory Support

32 gigabytes

1 terabyte

1 terabyte

1 terabyte

Host Processor Support

32 Cores (Max)

64 Cores (Max)

64 Cores (Max)

64 Cores (Max)

Virtual Networks

Unlimited

Unlimited

Unlimited

Unlimited

Guest VM Memory

32 GB (Max)

64 GB (Max)

64 GB (Max)

64 GB (Max)

Guest Virtual Processor

4 per VM (Max)

4 per VM (Max)

4 per VM (Max)

4 per VM (Max)

Guest Virtual NICs

4 Legacy

8 Synthetic

4 Legacy

8 Synthetic

4 Legacy

8 Synthetic

4 Legacy

8 Synthetic

Guest Storage Adapters

2 IDE

4 SCSI

2 IDE

4 SCSI

2 IDE

4 SCSI

2 IDE

4 SCSI

Guest Storage Devices

4 IDE

256 SCSI

4 IDE

256 SCSI

4 IDE

256 SCSI

4 IDE

256 SCSI

Cluster Support

N

Y

Y

Y

Quick Migration

N

Y

Y

Y

Live Migration

N

Y

Y

Y

As you can tell from the table, Hyper-V Server 2008 R2 core features are comparable to Windows Server 2008 R2 Enterprise Edition including failover clustering that enabling Quick Migration and Live Migration. However, it is important to remember that unlike Windows Server 2008 R2 which allows a full installation of Hyper-V, Hyper-V Server 2008 R2 is similar to a Server Core installation that provides only a local command-line and text-based configuration utility for management. That said, Hyper-V Server 2008 R2 can be managed remotely using the Hyper-V Manager and Failover Cluster Manager consoles.

As you read through the list of new features in the following section, keep in mind that they apply to Windows Server 2008 R2, as well as Hyper-V Server 2008 R2.

Live Migration

Live Migration provides the ability to move a virtual machine across cluster nodes within a single failover cluster without data loss or service interruption. Live Migration does not depend on either guest operating system or application failover clustering support. A live migration of a virtual machine can be initiated using the Failover Cluster Manager, System Center Virtual Machine, or a WMI or PowerShell script. However, you will need System Center Virtual Machine Manager R2 to initiate and manage Live Migration for Windows Server 2008 R2 Hyper-V and Hyper-V Server 2008 R2 servers.

Live Migration consists of a multistep process that includes the following phases:

  • Transfer of the virtual machine configuration data from the source node to the destination node. The data is used to create a new virtual machine with identical settings on the destination cluster node.
  • Transfer of the memory pages on the source node to the destination node. Hyper-V tracks modifications to the memory pages and iteratively copies the modified pages to the destination node. The process continues until an iteration threshold is reached or all modified memory pages are copied to the destination node.
  • Pause execution of the virtual machine to copy remaining modified memory pages, and transfer the processor register and device state from the source node to the destination node.
  • Assign the virtual machine storage, including virtual hard disks and pass-through disks, to the destination node.
  • Resume execution of the virtual machine on the destination node once the virtual machine is in a consistent state.
  • Update the physical network switch tables with the new port to direct the network traffic for the virtual machine.
  • Remove the virtual machine from the source node.

If you want to optimize the shared storage configuration of the failover cluster, and therefore the performance of Live Migration, you can implement Cluster Shared Volumes.

Cluster Shared Volumes

Cluster Shared Volumes (CSV) implements and presents a consistent file namespace to all failover cluster nodes and allows multiple cluster nodes to concurrently access a LUN on a shared storage system. To a virtual machine, a CSV volume appears as if it is stored on its own LUN. However, all of the virtual machine storage resides on a single LUN, and every cluster node can access the volumes using the same fully qualified path. Some of the other benefits of CSV include:

  • Full compatibility with NTFS (no need to reformat media)
  • Support for SAN, NAS, and iSCSI-based storage devices
  • Reduction in the number of drive letters implemented to store multiple VMs.

Second Level Address Translation

Windows Server 2008 R2 Hyper-V R2 leverages the Second Level Address Translation (SLAT) functionality that is implemented in AMD-V and Intel VT processor hardware architectures. AMD-V implements SLAT through a mechanism named Nested Page Tables (NPT), also referred to as Rapid Virtualization Indexing (RVI). The Intel VT SLAT technology is named Extended Page Tables (EPT). Using NPT or EPT, AMD-V and Intel VT processors can maintain and perform the two levels of address space translations required for each virtual machine in hardware, reducing the complexity of the Windows Hypervisor and the context switches needed to manage virtual machine page faults. As a result, Windows Server 2008 R2 Hyper-V provides better scalability of Hyper-V servers.

Core Parking

Windows Server 2008 R2 Hyper-V implements a new power management feature, Core Parking, that provides the ability to place processors into deep C-states (low power states) when the server workload can be managed by a fewer number of processor cores than are allocated to it. Instead of optimizing the scheduling of virtual machines across all available processor cores, the management partition kernel determines the set of processor cores to park and provides the information to the Windows Hypervisor. When the Windows Hypervisor schedules virtual machines for execution, it uses the Core Parking information to determine if it can avoid selecting processors that are parked. If the workload requires additional processor cores, processors are brought out of the C-state and back online to support virtual machine workloads.

Authorization Manager - Virtual Machine Snapshot Operation

There is a new Authorization Manager (AzMan) operation in Windows Server 2008 R2 Hyper-V, Allow Virtual Machine Snapshot, which you can use to delegate the permission to create virtual machine snapshots. This new operation provides the permission to create virtual machine snapshots without the privilege to start and stop a virtual machine, as is necessary in Windows Server 2008 Hyper-V.

Dynamic Addition and Removal of Storage

Windows Server 2008 R2 supports adding and removing virtual hard disks and pass-through disks to a running virtual machine without requiring a reboot, if Integration Services are installed and the disks are attached to virtual SCSI controllers.

TCP Offload Support

The TCP Offload feature in Windows Server 2008 R2 Hyper-V allows a virtual machine to push TCP/IP processing down to supported physical network adapters. Although this functionality is available in Windows Server 2008, it was not supported for virtual machines. In most cases, the networking offload support in Windows Server 2008 R2 Hyper-V reduces the load on processor cores, freeing processor time and improving overall virtual machine network performance.

Virtual Machine Queue Support

Windows Server 2008 R2 Hyper-V provides support for Virtual Machine Queue (VMQ) to help reduce the complexity and overhead associated with delivering network packets received by a physical network adapter to the target virtual machine. Specifically, a virtual machine queue is created on a network adapter for each virtual machine, and a VMQ identifier is assigned to each virtual machine. When a network packet arrives, the VMQ identifier is used for quick identification of the target virtual machine. In addition, network packets are directly copied into the target virtual machine memory, providing an increase in performance.

Jumbo Frames

In Windows Server 2008 R2 Hyper, jumbo frame support is extended to virtual network adapters. A jumbo frame is an Ethernet frame with up to 9000 bytes of payload data, as opposed to the Ethernet standard of up to 1500 bytes. Using jumbo frames reduces the overhead incurred for each transferred byte of network data. The results are additional performance enhancements due to significant processor and TCP/IP overhead reduction.

MAC Address Range

Another network-related feature in Windows Server 2008 R2 Hyper-V is the ability to manage the MAC address pool through the Virtual Network Manager. By default, there are only 256 virtual network adapters which can be concurrently assigned a dynamic MAC address. If you require more than 256 concurrent dynamic MAC address assignments on a single Hyper-V server, or you need to modify the MAC address pool to avoid duplicate MAC address assignments, you can use this new feature to affect the changes, without resorting to a more risky registry manipulation.

Hyper-V Default Folder Changes

There are two new default folders that Windows Server 2008 R2 Hyper-V creates during installation to store virtual machine–related files:

  • %SystemDrive%\ProgramData\Microsoft\Windows\Hyper-V\Snapshots Cache
  • %SystemDrive%\ProgramData\Microsoft\Windows\Hyper-V\Virtual Machines Cache

These folders are used to store XML files that contain the globally unique identifier (GUID) and the common name associated with a specific virtual machine. This allows Hyper-V to resolve and display the common name of a virtual machine, rather than just the GUID, even if the virtual machine storage location is offline or the virtual machine configuration file is not readily accessible.

Conclusion

As you can see, the new features in Windows Server 2008 R2 Hyper-V result in expanded functionality (Live Migration, Cluster Shared Volumes, and so on), and improved performance (Second Level Address Translation, TCP offloading, and so on). Download Windows Server 2008 R2 Hyper-V from here or Microsoft Hyper-V Server 2008 R2 here.

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