Overview of Xen Virtualization

1. What is Xen?

Xen virtual machine, or Xen VMM, is an open source project developed by the University of Cambridge Computer Lab, which enables users to create more virtual machines, each of which is an instance running on the same operating system.

2. There are two ways to run the Xen virtual machine

Fully virtualized (full virtualization)

Semi-virtualized (para virtualization)

Full virtualization provides the full abstraction of the underlying physical system and creates a new virtual system in which the client operating system can run. There is no need to modify the client operating system or the application (the client operating system or application runs as usual, unaware of the existence of the virtual environment).

Semi-virtualized requires modifications to the guest operating system running on the virtual machine (these guest operating systems realize that they are running in a virtual environment) and provide similar performance, but the performance of semi-virtualized is superior to full virtualization.

3. Features of Xen

1) Virtual machine performance closer to real hardware environment

2) free switching between platform and virtual platform of real physical environment

3) Support to 32 virtual CPUs per client virtual machine

4) X86/32,X86/64 platform supporting PAE instruction set

5) with Intel Virtual support VT support to use the virtual original operating system

6) Excellent hardware support, almost all Linux device drivers

4. The application scope of Xen

1) Server consolidation: Install multiple servers on a single physical host for demonstration and fault isolation

2) No hardware dependencies: allows the application and operating system to migrate new hardware to test

3) Multi-os configuration: Run multiple operating systems at the same time for development and testing purposes

4) Kernel development: Do kernel testing and debugging, do not need to set up a separate machine for testing

5) Cluster operations: Compared to individual management of each physical host, VM-level management is more flexible and easier to control and isolate in load balancing

6) hardware technical support for guest operating systems: New operating systems can be developed to benefit from extensive hardware support for existing operating systems

5. Hardware Support x86 series architecture

Intel series

Xecon 71xx 7041 7030 7020 5100 5050

Pentium D 920 930 940

Pentium 4 662 672

Core Duo T2600

On Core 2 Duo E6300

AMD series

AMD Athlon

AMD Duron

Intel series

6. Does the CPU support full virtualization

[Email protected] ~]# Cat/proc/cpuinfo |GREP Flags

FLAGS:FPU VME de PSE TSC MSR PAE MCE cx8 APIC Sep MTRR PGE MCA cmov Pat PSE36 clflush DTS MMX fxsr SSE SSE2 SS Syscall NX rdtscp lm constant_tsc up Ida Nonstop_tsc Arat pni vmx ssse3 cx16 sse4_1 sse4_2 popcnt lahf_lm

Note: ensure that the CPU supports Xen virtualization. Para-virtualization requires PAE, and full virtualization requires Intel VT or AMD PT support. Includes PAE, then it supports semi-virtualized. If you include VMX (Intel) or SVM (AMD), then full virtualization is supported.

Overview of Xen Virtualization