虚拟化技术比较 —— Virtualization

以下主 要列出 不影响 Ubuntu Server 性能的虚拟化技术

List of pages in CategoryVirtualization

Popular virtual machine applications

On the Ubuntu 10.04 > Ubuntu Server Guide > Virtualization

The default virtualization technology supported in Ubuntu is KVM , a technology that takes advantage of virtualization extensions built into Intel and AMD hardware . For hardware without virtualization extensions , Xen and Qemu are popular solutions.

 

KVM

Ubuntu uses KVM as the backend virtualisation technology and libvirt as its toolkit/API. Libvirt frontends for managing VMs include virt-manager (GUI) or virsh (CLI). Alternative management options include convirt (GUI) or convirt2 (WWW).

Notes

The use case targeted when KVM was moved into main is "server virtualization" . This means that even though KVM can be used to serve other purposes, it has been designed to be run on Ubuntu Server Edition to host non-graphical server operating systems . If you are looking for software to serve graphically-based virtual machines , VirtualBox , Parallels Workstation (or Parallels Desktop for Mac), or VMware Player/Server are more suitable alternatives.

 

Linux-KVM (for Kernel-based Virtual Machine ) is a full virtualization solution for Linux on x86 hardware containing virtualization extensions (Intel VT or AMD-V). It consists of a loadable kernel module , kvm.ko , that provides the core virtualization infrastructure and a processor specific module , kvm-intel.ko or kvm-amd.ko . KVM also requires a modified QEMU although work is underway to get the required changes upstream.

Using KVM, one can run multiple virtual machines running unmodified Linux or Windows images. Each virtual machine has private virtualized hardware : a network card, disk, graphics adapter, etc.

Installation

Check that your CPU supports hardware virtualization

To run KVM, you need a processor that supports hardware virtualization . Intel and AMD both have developed extensions for their processors, deemed respectively Intel VT-x (code name Vanderpool) and AMD-V (code name Pacifica). To see if your processor supports one of these, you can review the output from this command:

egrep -c '(vmx|svm)' /proc/cpuinfo 

If 0 it means that your CPU doesn't support hardware virtualization.

If 1 (or more) it does - but you still need to make sure that virtualization is enabled in the BIOS.

 

 

 

LXC

Linux Containers (LXC) provide lightweight virtualization that lets you isolate processes and resources without the need to provide instruction interpretation mechanisms and other complexities of full virtualization.

Notes

 

• Upstream libvirt support LXC.
• KVM + LXC can function properly on same host.
• LXC inside KVM works properly on same host.
• LXC take advantage of KMS feature of new Kernels.
• 64bit OS using a 32bit container.
• LXC works well with btrfs.
• No special hardware required.
• No patch is required to the kernel, since LXC is already integrated into the Kernel .
• OpenVZ Containers run on LXC, only Config modification required.

 

Xen

Xen is an open-source virtual machine layer which runs on the bare hardware , allowing multiple operating systems to run on the same hardware at the same time . It does this without emulation or instruction translation, and provides near-native ( ~97% ) CPU performance.

Xen is optimized for servers -- running many instances of Linux or other operating systems, each with their own kernel, securely and cleanly partitioned from each other, on one piece of server hardware . If you just want to run a virtual instance of windows on your workstation, then KVM or VirtualBox is probably what you want instead.

Xen is what has made " cloud computing " possible, including Amazon's EC2 . One of Xen's strengths is the ability to make this old hardware (circa Pentium III or later) usable again in a modern data center.

Server Virtualization with the Xen Hypervisor

 

Xen Cloud Platform - Advanced Virtualization Infrastructure for the Clouds