Hyper-V Features

New in Windows Server 2008 R2 with SP1, Dynamic Memory enables customers to better utilize the memory resources of Hyper-V hosts by balancing how memory is distributed between running virtual machines. Memory can be dynamically reallocated between different virtual machines in response to the changing workloads of these machines. Dynamic Memory thus enables more efficient use of memory while maintaining consistent workload performance and scalability. Implementing Dynamic Memory means that higher levels of server consolidation can be achieved with minimal impact on performance. Dynamic Memory also means larger numbers of virtual desktops per Hyper-V host for VDI scenarios. The net result for both scenarios is more efficient use of expensive server hardware resources, which can translate into easier management and lower costs. Historically, different methods have been used to deploy operating systems and applications to physical and virtual computers. For virtual computers, the .vhd file format has become a de facto standard for deploying and interchanging preconfigured operating systems and applications. Hyper-V in Windows Server 2008 R2 supports two important updates concerning .vhd files.

Windows Server 2008 R2 with Hyper-V includes the much-anticipated live migration feature. Data-centers with multiple Hyper-V physical hosts can move running virtual machines, VMs, to the best physical computer for performance, scaling, or optimal consolidation without affecting users; thereby reducing costs and increasing productivity. Service and maintenance can now be done in a controlled fashion during business hours increasing productivity for users and server administrators. Data centers can now also reduce power consumption by dynamically increasing consolidation ratios and powering off un-used physical hosts during lower demand times.

Windows Server 2008 R2 now supports up to 64 logical processors in the host processor pool. This is a significant upgrade from previous versions and allows not only greater VM density per host, but also gives IT administrators more flexibility in assigning CPU resources to VMs. Also new, Hyper-V processor compatibility mode for live migration allows lmigration across different CPU versions within the same processor family (for example, "Intel Core 2-to-Intel Pentium 4" or "AMD Opteron-to-AMD Athlon"), enabling migration across a broader range of server host hardware.

With Windows Server 2008 R2, Hyper-V uses Cluster Shared Volumes (CSV) storage to simplify and enhance shared storage usage. CSV enables multiple Windows Servers to access SAN storage using a single consistent namespace for all volumes on all hosts. Multiple hosts can access the same Logical Unit Number (LUN) on SAN storage. CSV enables faster live migration and easier storage management for Hyper-V when used in a cluster configuration. Cluster Shared Volumes are available as part of the Windows Failover Clustering feature of Windows Server 2008 R2.

Because of the architecture of CSV, there is improved cluster node connectivity fault tolerance that directly affects VMs running on the cluster. The CSV architecture implements a mechanism, known as dynamic I/O redirection, where I/O can be rerouted within the failover cluster based on connection availability.

Windows Server 2008 R2 includes a Best Practices Analyzer (BPA) for all major server roles, including Failover Clustering. This analyzer examines the best practices configuration settings for a cluster and cluster nodes.

Even with all the efficiency gained from virtualization, VMs still need to be managed. The number of VMs tends to proliferate much faster than physical computers because machines typically do not require a hardware acquisition. Therefore, management of virtual data centers is even more imperative than ever before.

The new Hyper-V leverages several new networking technologies contained in Windows Server 2008 R2 to improve overall VM networking performance.

Hyper-V in Windows Server 2008 R2 adds enhancements that reduce virtual machine power consumption. Hyper-V now supports Second Level Address Translation (SLAT), which uses new features on today's CPUs to improve VM performance while reducing processing load on the Windows Hypervisor. New Hyper-V VMs also consume less power by virtue of the new Core Parking feature implemented in Windows Server 2008 R2.

In Windows Server 2008 R2 there are three new networking features that improve the performance of virtual networks. Support for Jumbo frames, previously available in non-virtual environments, has been extended to work with VMs. This feature enables VMs to use Jumbo Frames up to 9014 bytes if the underlying physical network supports it. Supporting Jumbo frames reduces the network stack overhead incurred per byte and increases throughput. In addition, there is a significant reduction of CPU utilization due to the fewer number of calls from the network stack to the network driver. The Virtual Machine Queue (VMQ) feature allows physical computer network interface cards (NICs) to use direct memory access (DMA) to place the contents of packets directly into VM memory, increasing I/O performance.

Windows Server 2008 R2 Hyper-V supports hot plug-in and hot removal of storage. By supporting the addition or removal of Virtual Hard Drive (VHD) files and pass-through disks while a VM is running, Windows Server 2008 R2 Hyper-V makes it possible to reconfigure VMs quickly to meet changing workload requirements. This feature allows the addition and removal of both VHD files and pass-through disks to existing SCSI controllers for VMs.

Broad support for simultaneously running different types of operating systems, including 32-bit and 64-bit systems across different server platforms, such as Windows, Linux, and others.

Hyper-V includes new virtual switch capabilities. This means virtual machines can be easily configured to run with Windows Network Load Balancing (NLB) Service to balance load across virtual machines on different servers.

With the new virtual service provider/virtual service client (VSP/VSC) architecture, Hyper-V provides improved access and utilization of core resources, such as disk, networking, and video.

Hyper-V provides the ability to take snapshots of a running virtual machine so you can easily revert to a previous state, and improve the overall backup and recoverability solution.

Standards-based Windows Management Instrumentation (WMI) interfaces and APIs in Hyper-V enable independent software vendors and developers to quickly build custom tools, utilities, and enhancements for the virtualization platform.