四种虚拟化技术(简述虚拟化技术分类)

The most common server virtualization is KVM-QEMU (OpenStack uses this most), VMWare's ESX, Citrix's Xen, Microsoft Hyper-V, etc., Docker, a lightweight container technology, is also popular now.

Virtualization technology (Virtualization) and partition (Partition) technology are closely integrated
Since the birth of Unix in the 1960s Since then, virtualization technology and partitioning technology have begun to develop, and have experienced the development process from "hardware partition" -> "virtual machine" -> "paravirtual machine" -> "virtual operating system". The earliest partitioning technology was born out of people's need to improve mainframe utilization. For example, in fields such as finance and science, large Unix servers are usually worth tens of millions or even hundreds of millions of dollars. However, in actual use, multiple departments cannot share their computing power well, which often results in departments that need computing unable to obtain computing power. Departments that don't require a lot of computing power take up too many resources. At this time, partitioning technology appeared, which can divide a large server into several partitions, which are provided to the production department, testing department, R&D department and other departments respectively. In order to improve the performance of virtual machine technology (VirtualMachineMonitor), a new para-virtualization technology (Para-Virtualizion) technology was born. This virtual technology is represented by Xen, which is characterized by modifying the kernel of the operating system and adding a XenHypervisor layer. It allows multiple systems installed on the same hardware device to be started at the same time, and resource allocation is performed by XenHypervisor. In this virtual environment, it is still necessary to simulate hardware devices, install the Guest operating system, and modify the kernel of the operating system. Compared with the traditional Virtual Machine Monitor, Xen's performance is slightly improved, but it is not very significant. In order to further improve performance, Intel and AMD developed VT and Pacifica virtual technologies respectively, adding virtual instructions to the CPU. Using the hardware virtualization technology supported by the CPU, there is no need to modify the operating system kernel, but the CPU's unique instruction set performs the corresponding conversion operations. ——Compared with individual physical resource units, virtual resources can be allocated in smaller units. Compared with physical resources, virtual resources can recover faster after a crash because they do not have hardware and operating system problems.

Virtual reality technology has been recognized by more and more people. Users can experience the most realistic feeling in the virtual reality world. The authenticity of its simulated environment is difficult to distinguish between true and false in the real world, making people feel... An immersive feeling; at the same time, virtual reality has all the perceptual functions that humans have, such as hearing, vision, touch, taste, smell and other perceptual systems; finally, it has a super powerful simulation system, truly realizing the human-computer interaction Interaction allows people to operate at will and get the most realistic feedback from the environment during the operation process. It is the existence, multi-perception, interactivity and other characteristics of virtual reality technology that make it loved by many people