What is KVM

First, what is KVM

* The shorthand for kernel-based virtual machine is the latest virtualization technology launched by rhel5.4, which currently supports only 64-bit rhel5.4 running KVM, hardware needs to support VT technology, and KVM must be used in 64 bit environments.

Use the command to see if the system supports VT

Cat/proc/cpuinfo | grep ' VMX '

*KVM, formerly known as Qemu,08, was bought by Red Hat and acquired a technical hypervisor, but Redhat KVM is believed to be the mainstream of future Linux hypervisor.

Second, the composition of the KVM

* One is the device driver that manages the virtual hardware, which uses the string device/DEV/KVM as the management interface.

There are two modes of the *linux process: Kernel and user mode, and a new client mode for KVM addition.

Third, the role of KVM

* Increase resource utilization for physical servers (less input on hardware)

* Can be deployed in bulk

* Implement real-time Snapshot technology

* Support cloning technology

* Enable offline migration and dynamic migration of virtual machines (increase the flexibility of it deployments)

* Can dynamically adjust resources (traditional It architecture resources are fixed, cannot be dynamically allocated)

Four, the advantages of KVM

Advantages of *KVM and VMware

The bottom of the ESX is Vmkernel + linux,vmkernel start to take over the hardware management, then start the first Linux virtual machine, assist Vmkernel to manage and dispatch hardware resources together.

KVM is a direct turn Linux kernel into hypervisor, only need to boot from the standard Linux kernel, Linux kernel features can be fully utilized. The advantages of the KVM architecture make it very concise and are merged into the standard kernel within three months of development.

The advantages of *KVM and Xen

The biggest difference between KVM and Xen is the architecture, the KVM is built directly on top of the Linux kernel, the Linux kernel into the hypervisor, is the use of kernel existing functions based on the development of KVM does not have the functionality.

Xen hypervisor is built from scratch, scheduling management of hardware resources, management of virtual machines, and many interfaces incompatible with Linux kernel, and then for Xen,hypervisor to provide hardware access driver support for virtual machines through Domain0.

Although the 3.0 kernel is now combined with Xen, most Linux OS cores are 2.6, and even some new release OS, or 2.6 of the kernel, will have to be upgraded separately.

Listed above two examples, are compared with the KVM, but not on behalf of other virtualization technology is not good, everyone to do the technology are aware that the best for their own.

V. Development trend of KVM

*KVM Development Trend

With the development of virtualization technology, today's virtualization technology has moved towards the enterprise's key business areas. Red Hat launches a virtualization series based on the KVM kernel virtual machine technology, designed to apply virtualization technology to enterprise deployments, heterogeneous platform management, and cloud computing architectures.