Xen Virtualization Technology
Classification of virtualization technologies:
(1) Simulation: Emulation:
Qemu,PearPC,Bochs
(2) full Virtualization: Full Virtualization,Native Virtualization
HVM
VMware Workstation,VirtualBox,VMWare Server,Parallels Desktop,KVM,XEN
(3) paravirtualization: ParaVirtualization
GuestOS: know that you are running Virtualization
Hypercall
(4) OS-level virtualization:
Divide user controls into multiple, isolated from each other
Container-level virtualization
OpenVZ,LXC (LinuX Container), libcontainer,Virtuozzo,Linux V Servers
(5) Library-level virtualization
WINE
Type-I,Type-II
IaaS:Infrastructure, Infrastructure Servic
PaaS:Platfrom, platform as a Service
Xen:
University of Cambridge, open source VMM
Xen components: (1) Xen Hypervisor allocates CPU, Memory, Interrupt (2) Dom0 privilege domains, and Icano allocates network equipment net-front (GuestOS) Net-backend Block device block-front (GuestOS) Block-backend Linux Kernel: 2.6.37: start to support running Dom0 3.0. key features are optimized to provide management DomU toolstack to add, start, snapshot, stop, delete and other operations on virtual machines (3) DomU non-privileged domain, according to its virtualization implementation, there are many types of PV: paravirtualized HVM: hardware-assisted virtualization
Xen's PV technology:
Does not rely on the HVM feature of CPU, but requires the kernel of GuestOS to make changes to know that it is running in a PV environment
OS:Linux (2.6.24 +) running in DomU, NetBSD,FreeBSD,OpenSolaris
Xen's HVM technology:
Rely on Inter VT or AMD AMD-V, and also rely on Qemu to simulate IO devices
OS running in DomU: almost all that support this X86 platform
PV on HVM:
CPU runs in HVM mode
The IO device runs in PV mode
OS running in DomU: as long as OS can drive IO devices of PV interface type
Net-front,blk-front
Xen's tool stack:
Xm/xend: start the xend service in Xen Hypervisor's Dom0 traditional Chinese medicine
Xm: command line management tool with many sub-commands
Create,destroy,stop,pause...
Xl: based on the lightweight command line toolstack provided by libxenlight; xe/xapi: provides api for xen management, so it is mostly used in cloud environments, Xen Server,XCP virsh/libvirt:
XenStore:
A shared information storage space for each Domain, with a hierarchical namespace located in Dom0
CentOS support for Xen:
RHEL 5.7 Murray: the default virtualization technology is xen
Kernel version:2.6.18
Kernel-
Kernel-xen
RHEL 6: only kvm is supported
Dom0: not supported
DomU: support
How to use Xen on CentOS 6.6:
(1) compile the kernel version 3.0 and start the support for Dom0
(2) compiling xen programs
Projects related to the production of related programs:
Xen4centos
Xen made easy
Para Virt
Xen Para-virtualization Architecture
Xen tool:
