OpenStack has become a reality standard for cloud computing, and an important core of its reliance is virtualization technology

(1) The concept of virtualization

Virtualization is the simultaneous running of multiple virtual machines on physical devices that share the CPU, memory, and network of physical devices, but these VMs are isolated from each other.

The physical machine is called host (host), and the virtual machine is called guest.

(2) Classification of virtualization

Virtual machine scheduling management relies on hypervisor software, according to the location of hypervisor, can be divided into 2 major categories:

1, install hypervisor directly on hardware, the software is usually a customized Linux system. More commonly used are xen,vmware isxxx.

2, install hypervisor software on the general operating system, and then create the virtual machine on it, more commonly used kvm,virtualbox,vmware workstation.

(3) KVM

KVM is kernel-based Virtual machine, which is the implementation of KVM based on the Linux kernel,

(4) Libvirt

When it comes to KVM, I have to mention Libvirt, which is a KVM management tool. Libvirt not only manages KVM, but also manages Xen,virtualbox. The Libvirt is also used by the OpenStack bottom. It consists of 3 things:

The first part is the daemon program LIBVIRTD, used to come out hypervisor sent the request.

The second part is the API library, where developers can develop advanced tools based on libvirt, such as an example of a Virt-manager interface.

The third part is Virsh is the command line tool for KVM.

OpenStack has become a reality standard for cloud computing, and an important core of its reliance is virtualization technology