Shulou(Shulou.com)06/01 Report--

This article will explain in detail the relevant knowledge about how to understand virtualization and cloud computing. The content of the article is of high quality, so the editor will share it with you for reference. I hope you will have some understanding of the relevant knowledge after reading this article.

OpenStack is a cloud operating system, to learn OpenStack, we first need to master some relevant knowledge of virtualization and cloud computing.

Virtualization

Virtualization is the foundation of cloud computing. To put it simply, virtualization makes it possible to run multiple virtual machines on a physical server, and virtual machines share CPU, memory and IO hardware resources of physical machines, but logically the virtual machines are isolated from each other.

The physical machine is generally called the Host, and the virtual machine above the host is called the Guest.

So how does Host virtualize its hardware resources and make them available to Guest?

This is mainly achieved through a program called Hypervisor.

According to how Hypervisor is implemented and where it is located, virtualization can be divided into two types:

Type 1 virtualization and type 2 virtualization

Type 1 Virtualization

Hypervisor is installed directly on the physical machine, and multiple virtual machines run on the Hypervisor. The implementation of Hypervisor is generally a special customized Linux system. Both Xen and VMWare's ESXi fall into this type.

Type 2 Virtualization

Regular operating systems, such as Redhat, Ubuntu and Windows, are first installed on the physical machine. Hypervisor runs as a program module on OS and manages the virtual machine. KVM, VirtualBox, and VMWare Workstation all fall into this type.

In theory:

Type 1 virtualization generally optimizes hardware virtualization functions, and its performance is higher than that of type 2.

Type 2 virtualization is more flexible because it is based on a common operating system, such as supporting the nesting of virtual machines. Nesting means that you can run KVM again in the KVM virtual machine.

KVM

The following focuses on KVM, a type 2 virtualization technology.

Basic concept

The most popular and widely used virtualization solution on x86 platform is KVM. OpenStack also supports KVM best, and our tutorials naturally choose KVM as the Hypervisor of the lab environment.

KVM's full name is Kernel-Based Virtual Machine. In other words, KVM is implemented based on the Linux kernel.

KVM has a kernel module called kvm.ko, which is only used to manage virtual CPU and memory.

So who implements the virtualization of IO, such as storage and network devices?

This is left to the Linux kernel and Qemu to implement.

To put it bluntly, as a Hypervisor,KVM itself, it only focuses on virtual machine scheduling and memory management. The task of IO peripherals is left to the Linux kernel and Qemu.

Libvirt

You must often see Libvirt when you read KVM-related articles on the Internet.

What is Libvirt?

In short, it is the management tool of KVM.

In fact, Libvirt can manage not only Hypervisor such as KVM, but also Xen,VirtualBox and so on.

Libvirt is also used at the bottom of OpenStack, so it is necessary to learn.

Libvirt contains three things: background daemon program libvirtd, API library and command line tool virsh

Libvirtd is a service program that receives and processes API requests

The API library allows others to develop advanced tools based on Libvirt, such as virt-manager, a graphical KVM management tool, which we will discuss later

Virsh is the KVM command-line tool we often use, and there will be examples to use later.

As implementers of KVM and OpenStack, virsh and virt-manager must be able to use them.

This is the end of the knowledge about how to understand virtualization and cloud computing. I hope the above content can be helpful to you and learn more knowledge. If you think the article is good, you can share it for more people to see.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.