Virtualization Concept

VirtualizationReal: it exists, you can see it.

Transparent: it exists, you cannot see it

Virtual: it does not exist, you can see it

Gone: it does not exist, you cannot see it

Virtualization in Computing SystemsThe process of providing another image (logical grouping or

subset) of underlying computing resources

change computing system organization and profile

Computing system: CPU, memory, network, hard disk, software, user organization, ……

Methods: HW/SW partitioning (space-sharing), time-sharing, simulation, emulation, QoS, …

Why virtualization?Get a easy access interface and management interface

Get more powerful resource profile

Support multiple clients

Scenarios of Virtualization in computing systemHardware virtualization

Process level virtualization

High level language virtualization

OS level virtualization

Resource virtualization

Application virtualization Hardware/system

Process level

Language level

OS level

Application level

reso

urce

Hardware virtualization One server support multiple virtual machines

VMM (virtual machine monitor) or hypervisor

Granularity: virtual machine

We will focus this topic later

Process level virtualizationProvide the guest process with some runtime software

User could access a platform independent runtime environment

Granularity: process

Example: java executable

High level language virtualization Languages could be executed on multiple computing

architectures

Supported by compiler and runtime environment

Based on popular programming language: C, C++ and Fortran.

Granularity: language

Example: MPI, PVM

OS level virtualization A physical server is divided into multiple virtual servers

Guest OS is the same with original one

Supported by the OS kernel

Granularity: OS

Examples: Solaris Zones supports multiple guest OSes running under the same OS (such as Solaris 10)

Application level virtualization build application level virtualization in data management,

software library, programming interface, execution environment

Granularity: application environment

Example: Virtual Data System

Resource virtualization Organizing resource in a logical way

Present an easy use/management interface or powerful resource image

Granularity: resource image

Example: VPN, RAID, Cluster OS

almost all the computing resource interfaces are virtualized: memory, harddisk, network …

Philosophy of VirtualizationResource consolidation

Multiple resource items -> one resource image Example: Computer Cluster, Grid, RAID

Philosophy of VirtualizationResource multiplexing

One resource -> multiple resource instances Example: CPU, memory, VPN, Virtual machine