Infrastructure as a Service (IaaS) is also sometimes referred to as Hardware as a Service (HaaS). It is one of the three fundamental layers of cloud computing, the other two being Software as a Service (SaaS) and Platform as a Service (PaaS) .

IaaS is essentially defined as realigning the paradigm of infrastructural investment from an upfront capital outlay archetype to an ongoing operational expense in the form of virtualized utility. In other words, instead of categorizing computers, servers and software programs investments as capital expenditures, organizations are now able to conveniently participate in a pay-as-you-go model, leaving the infrastructural investments in the hands of cloud service providers.


Some may argue that the concept of IaaS have been utilized in the industry as far back as 20 years ago, and they will be partial justified in saying so. The precursor of IaaS is in the form of traditional data centers and web hosting services. However, compared to its prehistoric ancestors, IaaS, despite sharing the basic technology applications, has evolved into a completely different creature. It has become more and dynamically interactive creature, allowing theoretically unlimited offsite expansion and collaboration between providers and end users.

IaaS is typically characterized as:

• Web Based
• Offsite
• System Virtualization
• Maximum Redundancy
• Utility Economics
• Instant Scalability



Amazon Web Services and GoGrid are among the pioneers in the industry and despite their contrasting approach, easily provide the largest IaaS facility in the industry. However, of late, Rackspace has been making significant strides in the area and with its superior unallocated CPU cycles held in reserve, by as much as 3500% according to a report, they bear close scrutiny.
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