The components of the Cloud Infrastructure
This article will address the question of what is required to ‘create’ a cloud? A very simple but not altogether correct answer is exactly what is required to build and run any computer network.
The idea that the Cloud is some form of ethereal non existent body full of computer technology and databases is, alas, a myth.
The backbone of a Cloud Infrastructure is a server, or more usually a cluster of interconnected servers in data centres frequently spanning several countries, if not several continents. These servers have vast computational capabilities and provide the means by which Cloud customers can access network and storage resources. Typically a server would run a hypervisor, which in turn would run a virtual machine manager (VMM). The VMM in turn would control the starting, stopping and restarts of virtual machine (VM).
VMs provide almost instantaneous expansion and contraction of the Cloud Infrastructure to meet the Cloud users business requirements. VMs run a guest OS which allows the machine to run its specific software (applications).
Cloud Infrastructures rely on virtualisation to provide the flexibility and scalability that Cloud users require. The two recognised forms of virtualisation are full virtualisation and guest OS/VM models.
Full virtualisation is where the VM emulates the underlying hardware. The VMs remain independent and not aware of each other. A hypervisor is used as an intermediary for the communications between the guest OS and the underlying hardware
Figure 1 – Guest OS/VM model
In this model of virtualisation the operating system software is installed into the hardware as normal. The operating system is referred to as host operating system as it provides the execution environment for visualised applications.
Virtualisation software is then installed into the host operating system (similar to a hypervisor, but the virtualisation software runs on the host operating system (OS). Applications then run on the VM and again appear to the user as a real machine.
Besides all of the components above the following elements are also required to complete the Cloud Infrastructure. Infrastructure management tools such as cost tracking, provisioning and automation as well as cloud management. As with all IT systems security tools will need to be in place, including some Cloud specific security applications. Frequently overlooked when a move to Cloud computing is considered is the fact that users’ applications will need to be capable of running in the Cloud and accessing data stored on the Cloud servers.
In the next article the various types of Cloud deployment will be looked at.