An introduction to virtualization
Virtualization refers to the operation of computer elements on a virtual basis rather than a real basis. Virtualization technology can expand the capacity of hardware and simplify the process of software reconfiguration. The virtualization technology of the CPU can simulate multiple CPUs in parallel on a single CPU, allowing one platform to run multiple operating systems at the same time, and applications can run in independent spaces without affecting each other, thereby significantly improving the work efficiency of the computer.
2. Application scenarios
Virtualization technology is the foundation of cloud computing. Cloud computing is the product of the integration of traditional computer technologies and network technologies such as grid computing, distributed computing, parallel computing, utility computing, network storage, virtualization, and load balancing.
Second, the common virtualization technology
1. Open source virtual machine KVM
KVM (full name is Kernel-based Virtual Machine) is a full-featured virtualization solution on the x86 hardware platform under Linux, including a loadable kernel module kvm.ko provides and virtualized core architecture and processor specification modules.
Using KVM allows multiple, including Linux and Windows, to have proprietary hardware per virtual machine, including network cards, disks, and graphics adapters.
2. Open source virtual machine Xen
Xen is an open source hypervisor developed by the University of Cambridge. It is intended to run up to 100 fully featured operating systems on a single computer. The operating system must be explicitly modified ("ported") to run on Xen (but provide compatibility with user applications). This enables Xen to achieve high-performance virtualization without special hardware support.
3. Linux virtualization technology OpenVZ
OpenVZ is an operating system-level virtualization technology based on the Linux kernel and operating system . OpenVZ allows physical servers to run multiple operating systems, known as virtual private servers (VPS, Virtual Private Server) or virtual environments (VE, Virtual Environment).
Compared with VMware 's virtual machine and Xen 's para -virtualization technology, OpenVZ's host OS and guest OS must be Linux (although different Linux distributions can be used in different virtual environments). However, OpenVZ claims there are performance advantages to doing so. According to the OpenVZ website, there is only a 1-3% performance penalty for using OpenVZ compared to using a standalone server.
OpenVZ is the basis for Virtuozzo , a proprietary software developed by SWsoft, Inc. OpenVZ is licensed as GPLv2 .
OpenVZ consists of two parts, a modified operating system kernel and user tools.
4. Open source virtual machine VirtualBox
VirtualBox is a powerful x86 virtual machine software, which not only has rich features, but also has excellent performance. Even more gratifying is that VirtualBox went open source a few days ago, becoming a free software released under the GPL license.
5、Lguest
Lguest is a virtualization project initiated by IBM engineer Rusty Russell (Australian developer). It is a thin hypervisor (virtual machine management program) with only 5000 lines of code, which has been included in the latest version of the kernel. Similar to KVM, it supports the latest virtualization technologies from Intel and AMD chips. But unlike VMware's ESX Server, the operating system in the virtual machine created by Lguest knows that it is virtualized. So when invoking CPU cycles it can make requests directly to the real hardware instead of acting as an intermediary which reduces efficiency, so this architecture greatly improves efficiency. Lguest is licensed under GPL.