What is the Cloud?

What is the Cloud?

What is the Cloud? Well Cloud Computing is the latest in a long line of IT buzz words, but what does it really mean? Over the last week I was asked to explain what the Cloud was in layman’s terms a discovered that while I understood the technology behind Cloud computer and how it works I haven’t explained it in sufficient detail to a lay person before.  So I figured it would be a great topic for an article.

In traditional Micro-computing (as apposed to mainframes) you have an Operating System (Windows, Linux, UNIX, OSX) installed on a single computer (an example being for Windows or Mac desktop).  This can either be used as a Desktop, Workstation (high powered desktop) or a Server.  A server if you do not already know provides various services to end user devices like Desktops, Tablets Phone etc, whether it servers a files (File Server), shares a printer (Print Server), a website (Web Server) or various other functions.  In this case the Server Operating System was similar if not identical to the Operating System on your Desktop. Now the issue with this sort of computer is two fold. Firstly if something critical fails at the hardware level the computer goes offline and secondly the computer resources largely go unused.  The average file server for example uses only 5% of the capacity of the machine which of course is a waste of resources.


IBM Mainframe

IBM 704 mainframe from the 1960s

In the mainframe world things have been different for some time. With a mainframe each user connects to the main computer via a dumb terminal and everything the user does is handled by the central computer. To overcome the complexity of a single Operating System handling multiple users they had technology called Virtualisation, which provided a VM (Virtual Machine) for each logged in user, so in effect they had what appeared to be their own private computer.  This both allowed more efficient use of the central computer but also in time would prevent the task of one user effecting other users.

Now fast forward to the late 1990s where a company called VMware introduced this concept to personal computers. VMware was an instant hit for software developers because you could create a virtual machine as a test bed for their software and when something went wrong it would have minimal effect on the underlying system. They could also install various different versions of an operating system or a completely different operating system to test how the software ran on different platforms.

This technology has come a long way in the last 15 years to the point where most corporate systems are running on top of either VMware Virtualisation software or one of their competitors including Citrix (Xen) and Microsoft (Hyper-V). An example of one of these Cloud Solutions is Amazon Web Services (AWS) which is a massive Citrix Xen Cluster (multiple computers tied together to perform the same task) where Virtual Servers are created for people to use.

Confused yet? As one of my teachers said “a picture paints a thousand words”.  See below for further explanation.


A simplified diagram of the Cloud

A simplified diagram of the Cloud


To explain this diagram you have three (3) levels of cloud computing which are as follows:

IAAS – Infrastructure As A Service

With this service you get remote access to a Virtual Server.  In all respects this looks and behaves like a physical server though in fact it is a Virtual Machine running in whatever Virtualisation System the provider uses. This can be advantages if you require the flexibility or a dedicated server but no not have the resources to have an Enterprise grade physical compliment of server.

The primary disadvantages of this type of Cloud Service are twofold, firstly you still have to manage the server operating system which means taking care of software upgrades, patches and security.  The other disadvantage is that you are sharing the underlying computer so may not always get the best performance.

PAAS – Platform As A Service

This is where a developer who wants to run their software within a server environment without the cost and complexity or managing the underlying hardware and operating systems.  Microsoft, Google and Amazon supply these services. This can be a good alternative for people to try their latest web startup platform.  We also provide this service.

SAAS (Software As A Service)

These are the web services that the end user connects into, examples being Facebook, LinkedIn, Google, Gmail, the list is Virtually endless. This is the part of the Cloud infrastructure that the end user is receiving and is largely what most people are talking about when they refer to the Cloud.

For further reading you can try these articles:

Cloud computing – Wikipedia
With long history of virtualization behind it, IBM looks to the future – NetworkWorld

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