Virtualization Concepts: Difference between revisions
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Revision as of 20:41, 23 June 2017
Internal
Virtualization
Virtualization represents running software, usually multiple operating systems, concurrently and in isolation from other programs on a single system, called host. The software entity that controls virtualization is called hypervisor. The virtual machines executing on the host under the control of the hypervisor are known as guests or guest operating systems.
There are several types of virtualization: full virtualization allows for an unmodified version of the guest operating system. The guest addresses the host's CPU and other hardware resources via a channel created by the hypervisor. This is the most performant virtualization type, because the guest operating system communicates directly with the physical CPU. Paravirtualization requires a modified guest operating system, which communicates with the hypervisor. The hypervisor passes the unmodified calls from the guest to the CPU and other devices. Software virtualization or emulation uses binary translation and other emulation techniques to run unmodified guest operating systems. The hypervisor translated the guest calls to a format that can be understand by the host operating system.
Virtualization Platforms
- Red Hat Enterprise Linux as Virtualization Plaform
- Red Hat Virtualization
- Red Hat OpenStack Platform
- VMware vSphere
- Microsof Hyper-V
Hypervisor
The software entity that controls virtualization is referred to as hypervisor. The hypervisor manages the hardware resources of the host system and makes them available to the guest operating systems.
Hypervisors: KVM, Xen, VMware ESX.
Host Operating System
The host operating system (or the host OS) is the operating system of the physical computer on which the hypervisor is installed.
Guest Operating System
The guest operating system (or the guest OS) is the operating system that is running inside the virtual machine.
Virtual Machine
Hardware Virtualization Extensions
Hardware Devices and Virtualization
Migration
Migration describes the process of moving a guest virtual machine from one host to another. There are two types of migration: Offline migration suspends the guest virtual machine and then moves the image to the destination host. The virtual machine is then resumed on the destination host. Live migration is the process of migrating an active virtual machine from one host to another.