This module introduces the key concept of virtualization and the role this plays in effectively delivering cloud services, before defining the four different cloud deployment models.
The objectives of this course are to provide you with and understanding of:
- what virtualization is and how it relates to cloud computing.
- the four cloud deployment models and the application of each model.
The course is aimed at anybody who needs a basic understanding of what the cloud is, how it works and the important considerations for using it.
Although not essential, before you complete this course it would be helpful if you have a basic understanding of server hardware components and what a data center is.
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Virtualization is not a new concept, but without it, cloud services wouldn’t be possible.
We use virtualization every time we access the cloud and cloud services. But to understand it, you’ll first need to understand what a virtual machine – or VM – is.
What is a virtual machine?
A physical machine is a computer, like this Windows machine we’re all familiar with. It has a CPU, memory, a hard drive and a network connection. It could also be a laptop, tablet or other device. In the context of virtualization, the physical computer is called a ‘host’.
Virtualization is the process of using special software on a physical machine – the host – to create virtual machines. This special software is called a hypervisor and a virtual machine is called a ‘guest’. Modern virtualization tends to be hardware-based rather than software-based, which means we can use the host resources more efficiently.
A virtual machine is really just a file sitting on the hard drive and to users it appears and acts no differently to a physical computer. It can be configured to use any operating system with any amount of things like CPU capacity and storage space from its host. The only limit to how many virtual machines can be created and run is the host CPU, RAM and other resources. RAM especially is almost always the main limiting factor.
So together, all the virtual machines share the same resources of the host, but each virtual machine works independently of each other.
How does virtualization work?
Imagine a data center containing a large number of servers, each running a different application.
Some servers aren’t being used to their full capacity because the demand for that particular application is low, or the server capacity exceeds the potential demand. However, there’s still the associated cost of energy and resources to run the server, maximise its uptime, keep it updated and prevent it from crashing or overheating.
Virtualization eliminates this waste by enabling cloud providers (or any organization for that matter) to virtualize – or consolidate – the physical servers into fewer, more powerful and energy efficient servers. A virtual machine can then run separate operating systems and applications which are all installed on one physical server. Multiple virtual machines can run at the same time and share the underlying hardware resources, so they’re utilizing them much more efficiently.
This sharing of hardware resources is achieved through the hypervisor, which creates the virtualized environment, enabling multiple virtual machines to run on the same host.
The hypervisor sits between the physical server hardware and the virtual machines and creates a shared pool of virtual hardware resources for each of them to access. Any request to the hardware goes through the hypervisor, which ensures the resources are shared between all the virtual machines as they’re needed.
Benefits of virtualization
Virtualization provides the basis for cloud services because it allows providers to optimize their resources, which enables utility pricing and on-demand services.
There are obvious cost benefits of virtualization including reduced capital expenditure – less hardware’s needed because multiple virtual machines can run on a single host. And operating costs are lower because less space, power and cooling is required in the data center.
The isolation of each guest system in a virtual environment means a problem with one guest machine doesn’t affect the others and a security attack on one guest is unlikely to affect a host machine.
System back-up and recovery
Virtual machines are simply programs, so they can be easily copied and restored. ‘Snapshots’ enable multiple, identical copies of one virtual machine to be created so, if something happens to the system, the copy can be restored to its original state.
The optimisation of resources through virtualization means that cloud providers can offer an efficient and safe environment, and user organisations should expect to share those benefits through a flexible and cost-effective service.
There’s more information about what virtualization is and how it works in the TechTarget guide. You’ll find the link in the Cloud Literacy Resources.
Daniel Ives has worked in the IT industry since leaving university in 1992, holding roles including support, analysis, development, project management and training. He has worked predominantly with Windows and uses a variety of programming languages and databases.
Daniel has been training full-time since 2001 and with QA since the beginning of 2006.
Daniel has been involved in the creation of numerous courses, the tailoring of courses and the design and delivery of graduate training programs for companies in the logistics, finance and public sectors.
Previous major projects with QA include Visual Studio pre-release events around Europe on behalf of Microsoft, providing input and advice to Microsoft at the beta stage of development of several of their .NET courses.
In industry, Daniel was involved in the manufacturing and logistics areas. He built a computer simulation of a £20million manufacturing plant during construction to assist in equipment purchasing decisions and chaired a performance measurement and enhancement project which resulted in a 2% improvement in delivery performance (on time and in full).