Introduction to Virtualization Technology (reprint learning)

Virtualization of

Virtualization means that computer components run on a virtual basis rather than on a real basis. Virtualization technology can expand the capacity of the hardware, simplifying the software reconfiguration process. CPU Virtualization technology can simulate multi-CPU parallelism on a single CPU, allowing one platform to run multiple operating systems at the same time, and applications can be run independently of each other, thereby significantly increasing the productivity of the computer.

several kinds of virtualization software

1. RedHat KVM
Virtualization approach: Full virtualization

Architecture: Alien Architecture (Linux kernel); Naked Metal Architecture rhev-h

Features: Naked metal architecture rhev-h or support semi-virtualized virtio on critical hard drives and network cards for optimal performance.

I/O stack: KVM reuses the entire Linux I/O stack, so KVM users naturally get the latest driver and I/O protocol stack improvements.

Architecture diagram:



2. VmWare ESX
Virtualization approach: Full virtualization

Architecture: Bare Metal architecture

I/O stack: VMware chooses performance, but puts the I/O protocol stack into the hypervisor. Unfortunately, VMware Kernel is proprietary, which means that VMware has to develop and maintain the entire protocol stack, resulting in slower development, and your hardware may take some time to get VMware's support.

Architecture diagram:



3. Citrix XenServer
Virtualization: Semi-virtualized (Linux installation Linux), full virtualization (Linux installation Windows), hardware-assisted virtualization

Architecture: Bare Metal architecture

I/O stack: Xen chooses to maintain the road, which puts all I/O operations into the Linux guest, the so-called domain-0 inside. By reusing Linux for I/O, Xen maintainers do not have to rewrite the entire I/O protocol stack. Unfortunately, this sacrifices performance: each of these breaks must be scheduled by Xen to switch to domain 0, and everything has to go through an additional layer of mapping.

Architecture diagram:



4. Microsoft Hyper-V
Virtualization approach: Semi-virtualized

Architecture: Bare Metal architecture Hyper-V Server; Alien Architecture Windows 2008

Features: The location of the parent partition (host operating system) is moved to the sub-partition (virtual machine operating system) next to the host operating system and the virtual machine operating system is peer, no one who is attached to the relationship above.

I/O stack: All the devices The virtual machine sees are no longer virtual, and some of the hardware resources are real physical devices.

Architecture diagram:



Hardware Virtualization

Virtualization is a broad term that is a solution for simplifying management and optimizing resources. Like now open, transparent office buildings, the entire floor can hardly see the wall, the user may use the same cost to build more self-applicable office space, thereby saving costs and maximizing the utilization of space. The idea of re-planning a limited set of resources according to different needs to achieve maximum utilization is called virtualization technology in the IT field.

Hardware virtualization
The CPU virtualization technology is a hardware solution that enables virtual technology CPUs with specially optimized instruction sets to control virtual processes, which can easily improve performance compared to purely software-based virtualization technologies that are significantly more performance-based.

Virtualization Technology for Pure software
In a pure software virtualization solution, the operating system in the virtual machine is actually an application under the operating system, so the application on the virtual operating system will go through a communication layer more than the usual application.

Classification of virtualization technologies:
Platform Virtualization (Platform virtualization)
Virtualization for computers and operating systems.

Resource Virtualization (Resource virtualization)
Virtualization of specific system resources, such as memory, storage, network resources, and so on.

Application Virtualization (Application Virtualization)
Including simulation, simulation, interpretation technology and so on.

What we typically call virtualization is the platform virtualization technology that hides the actual physical characteristics of a particular computing platform by using control programs (control program, also known as virtual machine Monitor or Hypervisor), providing users with abstract, A unified, simulated computing environment (called a virtual machine). The operating system running in the virtual machine is called the guest OS, and the operating system running the virtual machine monitor is known as the host OS, and of course some virtual machine monitors can run directly above the hardware (such as VMWARE's ESX products) from the operating system. The real system that runs the virtual machine we call the host system.

Introduction to Virtualization Technology (reprint learning)