Windows Server 2008 R2 : Hyper-V feature focus - Introduction to Virtualization and Hyper-V, Hyper-V Changes

1. Introduction to Virtualization and Hyper-V

Virtualization technologies have been around the computing world for years; however, the technology has only become a key component to the ever-growing datacenter in the past few years. In recent years, organizations began noticing that the advancement of server CPUs and memory was outpacing operating systems. Many companies found themselves deploying servers where CPU and memory utilization was less than 20% on a regular basis. This is where server virtualization comes in. Server virtualization is a technology that provides the ability to run multiple, isolated operating systems on a single piece of server hardware allowing a much higher level of resource utilization.

Many IT organizations are finding their datacenters with less available power to deploy new server hardware, more expensive network connections, and increased cost in administering hundreds or thousands of servers. As an IT administrator, you have to face the fact that deploying hardware is not cheap. This has sparked the demand for server virtualization technologies. So much that some organizations choose to make virtual machines (VMs) the first option when deploying new systems. Today you can find server virtualization solutions supporting a wide array of systems in development, quality assurance, and production environments. If you have not considered server virtualization, you may want to take a deeper look. Figure 1 depicts how a hypervisor works to host VMs.

Figure 1. Server virtualization.

Microsoft openly expressed that it was committed to being a leader in the server virtualization market with the release of its first true bare-metal type 1 hypervisor in Windows Server 2008 R1. Microsoft further expressed this commitment by evolving Hyper-V by adding new features such as Live Migration with the Windows Server 2008 R2 release. With the addition of new features, and a price tag lower than competitive virtualization technologies, adoption of Hyper-V is seeing a steady increase with each version.

Before deploying Hyper-V, you may find it helpful to understand some of the basics of the hypervisor’s architecture. Hyper-V’s architecture involves a parent partition that manages the virtualization layer including the VMs running on the server. Hyper-V also installs the device drivers in each guest operating system opposed to the hypervisor. This allows the hypervisor to remain small and optimized for performance. The Hyper-V architecture is depicted in Figure 2.

Figure 2. Hyper-V architecture.

Notes From the Field

Hyper-V for disaster recovery

Many organizations use server virtualization technologies to support their disaster recovery plans. Using Hyper-V allows administrators to quickly and easily bring up new servers on demand. Additionally, VM disks are also stored as VHD files on the host. This allows easy backup of the entire VM.

2. Hyper-V Changes

Windows Server 2008 R2 includes several new enhancements to Hyper-V virtualization services. These enhancements include Live Migration, hot adding and removal of virtual disks, new processor features, and support for jumbo frames on VMs.

Live Migration

Windows Server 2008 R2 includes a much welcomed feature to enhance the process of moving VMs from one Hyper-V host to another. Windows Server 2008 R1 includes a feature known as Quick Migration, which suspends VMs and quickly transfers them to another host. This process does however cause a brief outage to any VMs being moved. When using Quick Migration to move a VM, some applications on that VM may time-out and need to be restarted because of their sensitivity to network or machine disruptions.

Live Migration allows Hyper-V to overcome these limitations when moving VMs by removing the need for them to be temporarily suspended thus removing downtime for applications running on the VMs being moved. Live Migration uses a process to transfer memory pages from the current host to the destination host and then simply transfers ownership of the VM’s virtual disks to the destination host.

Live Migration allows administrators to easily, on the fly, add new hosts to a Hyper-V cluster instantly increasing resources needed for VM workloads. Live Migration can also be used to allow administrators to service hosts during normal business hours without impacting on business services and applications. For example, an administrator might want to add additional memory to a Hyper-V host. He could use Live Migration to move any active VMs from the host to another host in the cluster. He could then turn off the host to add additional memory. After adding memory, the administrator could use Live Migration to move the VM workloads back to the host.

Live Migration requires that Hyper-V be deployed on a Windows Server 2008 R2 fail-over cluster. Additionally, Live Migration requires a dedicated network adapter on each Hyper-V host for migration traffic. It is also recommended that processors on all hosts are from the same manufacturer and of the same processor family. This ensures that all processor features can be used.

Processor enhancements

Windows Server 2008 R2 Hyper-V includes several new processor enhancements including support for 64 processor cores per physical host. Hyper-V can also take advantage of Windows Server 2008 R2 Core Parking features. Hyper-V moves VM CPU loads to the fewest required number of processor cores, allowing Windows to suspend the cores not being used. As workloads require more CPU resources, the cores are no longer suspended and Hyper-V moves VM workloads to those cores.

Storage enhancements

Windows Server 2008 R2 Hyper-V adds new storage features that allow administrators to easily add and remove VM storage. Hyper-V now allows administrators to add or remove virtual and physical storage hot while the VM is still running. This feature allows administrators to easily reconfigure VM storage without requiring downtime. For example, assume that a production SQL server needs additional storage space for more databases. As the administrator, you can add a new virtual disk drive to store new databases without taking the server offline.

Network enhancements

Hyper-V takes advantage of some of the new networking technologies in Windows Server 2008 R2 including TCP offload, also known as VM Chimney, and jumbo frames. These technologies provide better performance of VMs needing to access data on iSCSI SANs.