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Microkernelized hypervizor
In the last post from the series “Virtualization types”, I’m gonna explain you microkernelized hypervizor, model that is used in Windows Server 2008 for server virtualization. Comparing to monolithic hypervizor, microkernelized hypervizor has no drivers running within it. Instead, all drivers are run in each partition so that each guest OS running within a virtual machine can access the hardware through the hypervizor. This arrangement makes each virtual machine a completely separate partition for greater security and reliability.
A partition is the basic unit of isolation supported by hypervizor. A partition is made up of a physical address space together with one or more virtual processors, and administrators can assign specific hardware resources to the partition. The parent partition is the partition that creates and manages the child partitions, and it contains a virtualization stack that is used to control these child partitions. The parent partition is also the root partition because it is the partition that is created first and owns all resources not owned by hypervizor. And being the default owner of all hardware resources means the root partition is also in charge of power management, plug and play, managing hardware failure events, and even loading and booting the hypervizor.
This partition is our Windows Server 2008 installation. So, first we have to install Windows Server 2008, then we have to install Hyper-V role, which will load hypervizor above hardware and beneath Windows Server 2008, and will create partition for Windows Server 2008. That means that Windows Server will become “virtual“. And now, using Virtual Machine Manager tool from Windows Server 2008 (parent, root) we can create other virtual machines (child), which can be either Windows Server 2008, or any other operating system.
Performance of this model is great, because child partition does not have to go through host OS (Windows Server 2008) to access hardware, it just have to go through Hyper-V hypervizor (which is aroung 600kb in size). Because size of hypervizor is very small, there is small footprint, and security is much higher comparing to monolithic hypervizor because there is smaller attacking surface. These are the reasons why mickrokernelized hypervizor is used in Windows Server 2008, but also it is used in WMWare ESX Server.
Resources:
Monolithic hypervizor
Type 1 virtualization
Hybrid virtualization
Type 2 virtualization
Does server virtualization reduce costs?
Why should you use OS virtualization?
Virtualization today
Virtualization on brajkovic.info
Introducing Windows Server 2008 by Mitch Tulluch
By Ilija Brajkovic | December 4, 2008
Tags: hyper-v, microkernelized, tutorial, virtualization
Category: virtualization | Comments
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