Bare metal environment

A virtual environment where the virtualization product is directly installed on physical hardware, acting like a host OS. The opposite of hosted environment.

Binary Translation (BT)

Technique used by virtualization softwares to translate instruction set guest OSes send to virtual hardware in instruction set understandable by physical hardware. It's an alternative approach to paravirtualization.

Blade

A hot-pluggable motherboard, equipped with processors, memory and disks for use in a Blade Server.

Blade Server

An emerging modularized server configuration made by a standard rack featuring an embedded networking subsystem and several bays, where blades can be plugged while the system is turned on.

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Capacity Planning

The operation of calculating how many resources a physical server will need for hosting a certain amount of virtual machines. It's a critical task to be achieved at very beginning of any virtualization project.

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Emulation

A software technology allowing an operating system or an application to run on hardware other than the one for which it was developed.

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Grid Computing

An emerging computing model where a large amount of geographically separated, networked computers work like one single abstract infrastructure, able to compute multiple, complex tasks in parallel, required by multiple customers at a time.

Guest OS

The operating system installed inside a virtual machine (or a partition). In a virtualization solution the guest OS can be completely different from the host OS.

In a partitioning solution the guest OS must be identical to the host OS.

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Hypervisor

The virtualization software layer managing hardware requests from a guest OS, simulating answers from a real hardware. Used as VMM (Virtual Machine Monitor) synonymous.

Host OS

The operating system hosting one or more virtual machines (or partitions) and sharing physical resources with them. It's where the virtualization product or the partitioning product is installed.

Hosted Environment

A virtual environment where the virtualization product is installed on top of a host OS, instead of being installed on physical hardware.

The opposite of bare metal environment.

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Live Backup

The operation of copying a whole virtual machine, while powered on, at the host OS level, for archiving purposes.

Live Migration

The operation of moving a virtual machine, while powered on, from a host OS to another host OS, for maintenance or server consolidation purposes.

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P2V (Physical to Virtual) migration

The operation of migrating an operating system and every application installed on it from a physical computer to a virtual machine (or a partition), without reinstalling anything.

The opposite of V2P (Virtual to Physical) migration.

Para-virtualization

An enhancement of virtualization technology, where guest OSes need to be adapted (recompiled) before being ready for installation inside virtual machines.

It reduces virtualization overhead and improves performances.

It's an alternative approach to Binary Translation (BT).

Partitioning

A software technology able to create multiple instances of the same host OS, called partitions, instead of reproducing multiple different physical machines like in virtualization.

Partition

An isolated, new instance of the host OS, lying on it, and featuring autonomous characteristics like host name, network settings and installed applications.

Partitions are management by a partitioning solution.

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SAN (Storage Area Network)

A high-speed, high-available storage system, able to serve multiple computers at a time, dedicated to backup and archival purposes.

It can be reached by Fibre Channel (FC) or iSCSI protocols.

Server Consolidation

The operation of mitigating the so called server sprawl by optimizing resource usage and simplifying management of available computers.

Consolidation can be logical (managing distributed computers with central management) physical (moving several computers in a central location) or rationalized (migrate several computers in virtual machines or partitions, hosted by a single physical computer).

Server Sprawl

The irrational proliferation of multiple computers inside a company infrastructure.

SLA (Service Level Agreement)

An agreement between a service provider and a customer regulating offered service in several aspects, from amount of resources available to time availability, up to faults recovery timeframe.

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Utility Computing

An emerging business model where customers don't buy computer hardware but pay for its usage. Service providers own computer hardware leasing computation time on demand.

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V2P (Virtual to Physical) migration

The operation of migrating an operating system and every application installed on it from a virtual machine or a partition to one or multiple physical computers, without reinstalling anything.

The opposite of P2V (Physical to Virtual).

V2V (Virtual to Virtual) migration

The operation of migrating an operating system and every application installed on it from a virtual machine or partition hosted in a virtual infrastructure to another virtual machine or partition hosted in a different virtual infrastructure, without reinstalling anything.

Mainly used when working with different virtualization technologies in the same environment.

Virtual Machine

An empty, isolated, virtual environment, lying on top of a host OS, equipped with virtual hardware (processor, memory, disks, network interfaces, etc.) and managed by a virtualization product.

It's where the guest OS is installed.

Virtualization

A software technology allowing an operating system to run unmodified on an isolated virtual environment, called virtual machine, where a platform's physical characteristics and behaviours are reproduced.

VMM (Virtual Machine Monitor)

The virtualization software layer managing hardware requests from a guest OS, simulating answers from a real hardware.

Used as Hypervisor synonymous.

VSMP (Virtual Symmetric Multiprocessing)

The feature of mapping two or more virtual processors inside a single virtual machine or partition.

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Workload Management

The operation of handling computation power demand and computation power unavailability.

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