The first major provider of infrastructure as a service (IaaS) was Amazon in 2008. IaaS is a cloud computing service model by means of which computing resources are supplied by a cloud services provider. The IaaS vendor provides the storage, network, servers and

virtualization In computing, virtualization or virtualisation (sometimes abbreviated v12n, a numeronym) is the act of creating a virtual (rather than actual) version of something at the same abstraction level, including virtual computer hardware platforms, stor ...

(which mostly refers, in this case, to emulating computer hardware). This service enable users to free themselves from maintaining an on-premise

data center A data center (American English) or data centre (British English)See spelling differences. is a building, a dedicated space within a building, or a group of buildings used to house computer systems and associated components, such as telecommun ...

. The IaaS provider is hosting these resources in either a public cloud (meaning users share the same hardware, storage, and network devices with other users), private cloud (meaning users does not share these resources), or hybrid cloud (combination of both). It provides the customer with high-level APIs used to

dereference In computer programming, the dereference operator or indirection operator, sometimes denoted by "*" (i.e. an asterisk), is a unary operator (i.e. one with a single operand) found in C-like languages that include pointer variables. It operates ...

various low-level details of underlying network infrastructure like backup, data partitioning, scaling, security, physical computing resources, etc. A

hypervisor A hypervisor (also known as a virtual machine monitor, VMM, or virtualizer) is a type of computer software, firmware or hardware that creates and runs virtual machines. A computer on which a hypervisor runs one or more virtual machines is called ...

, such as Xen,

Oracle VirtualBox Oracle VM VirtualBox (formerly Sun VirtualBox, Sun xVM VirtualBox and Innotek VirtualBox) is a type-2 hypervisor for x86 virtualization developed by Oracle Corporation. VirtualBox was originally created by Innotek GmbH, which was acquired by ...

, Oracle VM, KVM,

VMware ESX VMware ESXi (formerly ESX) is an enterprise-class, type-1 hypervisor developed by VMware for deploying and serving virtual computers. As a type-1 hypervisor, ESXi is not a software application that is installed on an operating system (OS ...

/ESXi, or

Hyper-V Microsoft Hyper-V, codenamed Viridian, and briefly known before its release as Windows Server Virtualization, is a native hypervisor; it can create virtual machines on x86-64 systems running Windows. Starting with Windows 8, Hyper-V superseded W ...

runs the virtual machines as guests. Pools of hypervisors within the cloud operational system can support large numbers of virtual machines as well as the ability to scale services up and down according to customers' varying requirements.

Overview

Typically IaaS involves the use of a cloud orchestration technology like

OpenStack OpenStack is a free, open standard cloud computing platform. It is mostly deployed as infrastructure-as-a-service (IaaS) in both public and private clouds where virtual servers and other resources are made available to users. The software pl ...

Apache CloudStack CloudStack is open-source cloud computing software for creating, managing, and deploying infrastructure cloud services. It uses existing hypervisor platforms for virtualization, such as KVM, VMware vSphere, including ESXi and vCenter, and X ...

OpenNebula OpenNebula is a cloud computing platform for managing heterogeneous distributed data center infrastructures. The OpenNebula platform manages a data center's virtual infrastructure to build private, public and hybrid implementations of Infrastru ...

. It manages the creation of a virtual machine and decides on the hypervisor (i.e. physical host) in order to start it whilst enabling VM migration features between hosts, allocates storage volumes, and attaches them to VMs that track usage information for billing and more. An alternative to hypervisors is Linux

containers A container is any receptacle or enclosure for holding a product used in storage, packaging, and transportation, including shipping. Things kept inside of a container are protected on several sides by being inside of its structure. The ter ...

, which run in isolated partitions of a single

Linux kernel The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU ...

running directly on the physical hardware. Linux

cgroups cgroups (abbreviated from control groups) is a Linux kernel feature that limits, accounts for, and isolates the resource usage (CPU, memory, disk I/O, network, etc.) of a collection of processes. Engineers at Google started the work on this ...

and namespaces are the underlying Linux kernel technologies used to isolate, secure and manage the containers. Containerisation offers higher performance than virtualization because there is no hypervisor overhead. IaaS clouds often offer additional resources such as a virtual-machine disk-image library, raw

block storage In computing (specifically data transmission and data storage), a block, sometimes called a physical record, is a sequence of bytes or bits, usually containing some whole number of records, having a maximum length; a ''block size''. Data t ...

, file or

object storage Object storage (also known as object-based storage) is a computer data storage that manages data as objects, as opposed to other storage architectures like file systems which manages data as a file hierarchy, and block storage which manages data a ...

, firewalls, load balancers, IP addresses, virtual local area networks (VLANs), and software bundles. The

NIST The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into physical sci ...

's definition of

cloud computing Cloud computing is the on-demand availability of computer system resources, especially data storage ( cloud storage) and computing power, without direct active management by the user. Large clouds often have functions distributed over mu ...

defines infrastructure as a service like: According to the

Internet Engineering Task Force The Internet Engineering Task Force (IETF) is a standards organization for the Internet and is responsible for the technical standards that make up the Internet protocol suite (TCP/IP). It has no formal membership roster or requirements an ...

(IETF), the most basic cloud-service model offered by the providers is

IT infrastructure Information technology infrastructure is defined broadly as a set of information technology (IT) components that are the foundation of an IT service; typically physical components (computer and networking hardware and facilities), but also vario ...

–

virtual machine In computing, a virtual machine (VM) is the virtualization/ emulation of a computer system. Virtual machines are based on computer architectures and provide functionality of a physical computer. Their implementations may involve specialized h ...

s and other resources – as a service to subscribers. IaaS-cloud providers supply these resources on-demand from the large pools of equipment installed in

data centers A data center (American English) or data centre (British English)See spelling differences. is a building, a dedicated space within a building, or a group of buildings used to house computer systems and associated components, such as telecommun ...

. For wide-area connectivity, customers can use either the Internet or

carrier cloud In cloud computing a carrier cloud is a class of cloud that integrates wide area networks (WAN) and other attributes of communications service providers’ carrier grade networks to enable the deployment of highly complex applications in the cl ...

s (dedicated

virtual private network A virtual private network (VPN) extends a private network across a public network and enables users to send and receive data across shared or public networks as if their computing devices were directly connected to the private network. The b ...

s). To deploy their applications, cloud users install operating-system images and the application software on the cloud infrastructure. In this model, the cloud user patches and maintains the operating systems along with application software. Cloud providers typically bill IaaS services on a utility computing basis: cost reflects the number of resources allocated and consumed.

References

{{Cloud computing As a service Cloud computing

Overview

See also

References