Choosing a Server Virtualization Platform - Part 2 (Types of Hypervisor Technology)
<< Part 1 - Understanding Virtualization
Types of Hypervisor Technology.
Depending on their implementation, there are basically two types of ways in which Hypervisors work. They are called Type I and Type II hypervisors. All products that implement Hypervisor technology fall into one of these two types.
Type I Hypervisors run directly on the Hardware. Instead of the Operating system, they are fully in charge of the management of system resources. The operating systems run on top of the Hypervisor which intercepts their requests and manages them in such a way that they are completely independent of each other.
Figure 1
A Type I approach to Hypervisors
As can be seen in Figure 1, the three guest operating systems (OS’s) are running on top of the
hypervisor. The OS’s see only those resources that the Hypervisor presents to them.
As can be seen from the above figure, the guest operating systems run at the second level above the hardware.
Type II Hypervisors run on an existing operating system that provides the interface. The guest operating systems then run on the Type II hypervisor at the third level above the hardware as can be seen in Figure II.
Figure 2
A Type II approach to Hypervisors
Once more, as in Type I, the three guest OS’s are unaware of the fact that they are running on anything but the hardware directly.
Comparison of the two Types of Hypervisors.
For speed and efficiency, the Type I Hypervisors are definitely better. Since they run directly on the hardware and manage it face to face, they are able to work without cutting through the various layers that hamper the speed of the Type II Hypervisors.
Type II Hypervisors run on client systems where considerations of speed are less important. They can be installed directly on the Operating system and are thus much easier to setup. In addition, Type II Hypervisors support a much broader range of hardware since the hardware resources are provided by the underlying Operating System on which it runs.
Examples of Type I Hypervisors are Microsoft’s Hyper-V and ESX Server. Examples of Type II Hypervisors are VMServer and Microsoft’s Virtual Server
This entry was posted on Thursday, November 13th, 2008 at 12:38 pm and is filed under Blog Posts, Server Virtualization. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
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