Experts analyze the differences between Microsoft Hyper-V virtualization architecture and VMware

The technological advances in virtualization have become a common topic. What progress will be made in the near future is also a question worth figuring out. Microsoft's Virtualization product Hyper-V, formerly known as Viridian and WSVWindows Server Virtualization alization), provides a completely new Virtualization architecture and will be released as a component of the Windows Server 2008 platform.

Although the ultimate version of Hyper-V is only available for a while, the preview version of this technology is available. Anil Desai, a special virtualization expert in TechTarget China, will describe the Hyper-V Technical Architecture and explain what IT means for IT organizations. The latest Microsoft Hyper-V Server is the only hypervisor-Based Server Virtual Product.

Hyper-V hypervisor Architecture

In the Microsoft Hyper-V model, the hypervisor layer runs directly on the physical server hardware. All virtual partitions communicate with hardware through the hypervisor. The hypervisor is a very small and efficient code set that coordinates these calls.

Figure 1 shows the structure of Hyper-V.

Microsoft Hyper-V Architecture Overview

In the figure, each partition represents a virtual machine. The parent partition must run Windows Server 2008, which contains a virtual heap virtualization stack ). This heap contains management tools and automatic operation components, such as WMIWindows management specifications) interface. Each sub-partition can have its own sub-operating system. Note that all operating systems run in partitions, including the operating system of the parent partition that may be considered as the primary operating system.

So far, this may seem very simple. However, it also has some important architectural differences with the current virtualization method.

Rely on VMBus

Hypre-V contains a very small microkernel structure, which allows multiple partitions to access the same physical hard disk resource. Keeping hypervisor small helps reduce the security attack area and also help to maintain efficiency. Sub-partitions need to communicate with the parent partition for management. This can be done by using the logical point-to-point VMBus. Employees process service management operations and requests for each sub-partition, such as starting or monitoring virtual machines. VMBus uses shared storage to securely communicate with virtual machines on the same host server.

Driver differences

A very annoying part of dealing with virtual machines is the hardware driver. In most cases, you are restricted by the virtual hard disk layer, which is exposed by your virtualization platform. Due to compatibility, most virtualization solutions simulate the hardware environment. If it was in the middle of 1990s, the simulated hardware environment would be very popular, but it is similar to the modern server, it is similar to the TRS-80. This means that you have two dependencies:

1) physical hardware must support the virtual simulation layer;
2) The sub-operating system must have a simulated hardware driver. Generally, you have the necessary drivers to support physical hardware, but there is no driver for Virtual Hardware.

The biggest difference between the Hyper-V method and other hypervisor-based products, such as the VMware ESX Server platform, is that the drive operates differently. In Hyper-V, the drive is installed in the sub-operating system, not in the hypervisor layer. In this way, the vendor and administrator can use the driver designed for the physical hardware of the server, rather than the virtual hardware drive.

Enlightenment: Sub-OS type

At present, most potential sub-operating systems are not aware of virtualization. They thought they were running directly on the server hardware, so they needed to use the hardware simulation provided by hypervisor. Each partition that supports "No hypervisor-aware Operating System" uses the Hyper-V simulation layer. This applies to legacy operating systems as well.

To make full use of the Hyper-V architecture, the sub-operating system can use "enlightenments enlightenment". This is what Microsoft currently calls it ). A enlightened sub-operating system remembers virtualization and can communicate effectively with hypervisor. The enlightened child machine runs its own driver, which can communicate with the physical hardware of the server. For example, a disk-related call can be directly connected to the underlying direct storage array that uses SCSI connections. IHVs and OEMs can create their own operating system drivers.

Which operating system can be considered as an inspiration? Although official details have not yet been released, Windows Server 2008 is absolutely feasible. Windows Server 2003 and Windows Vista may be enlightened after they are updated. Microsoft has also partnered with Citrix XenServer, formerly known as XenSource, to provide a new Hyper-V driver for Linux-based release. Over time, more operating systems will support these enlightenment to improve performance, security, and compatibility.

Related Articles]

• Virtualization: How does Xen face VMware and Hyper-V?

• Virtualization: How does Xen face VMware and Hyper-V?

• High Availability Real-Time Migration Technology for Hyper-V and VMware

• Topic: Windows Server 2008