A couple of weeks back, I wrote about what Cloud computing is and we discussed a few examples of SaaS. Today I will talk about IaaS(Infrastructure as a Service)
IaaS is the most basic of the cloud computing services. Putting it simply, servers are rented out to the users for virtual use. Computers are provided by the cloud service providers to the end user, to use sometimes as physical but mostly as virtual resources. The user runs these virtual machines as a guest using a hypervisor.
A hypervisor also known as a Virtual Machine Manager (VMM) is a hardware virtualisation technique that allows multiple operating systems to run concurrently on a host computer. Some examples of a hypervisors that are used in IaaS are Xen and KVM (Kernel based Virtual Machine).
The cloud computing service providers manage pools of hypervisors in order to manage to cater to a large number of virtual machines. Some more examples of Iaas could include songs in a virtual machine music library, file-based storage and IP addresses. VLANs are also one such example. A Virtual Lan is a group of hosts , that even though they might not belong to the same physical location, communicate with each other as part of the same broadcast domain.
The hypervisor pools are usually installed in data centers. From here the cloud service providers supply the required resources on demand. Mostly for the Wide area connectivity, the Internet is used. However, in some scenarios Carrier Clouds are used.
Unlike SaaS, Cloud users have to install the operating system images along with the application software on their machines. Here it is the cloud user who is responsible for maintenance of the operating system and the software.
Iaas services are typically billed on a utility computing basis. Utility computing is basically the packaging of resources as a metered service. The advantage is that there is almost no cost to aqcuire the computer resources, and the computational resources are rented.
Some examples of IaaS include Amazon CloudFormation, Rackspace Cloud and Google Compute Engine
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