Virtualization Concept

Virtualization  Real: 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 Systems  The 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 system  Hardware 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 resource

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 virtualization  Provide 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 Virtualization  Resource consolidation  Multiple resource items -> one resource image  Example: Computer Cluster, Grid, RAID

Philosophy of Virtualization  Resource multiplexing  One resource -> multiple resource instances  Example: CPU, memory, VPN, Virtual machine