What is Cloud?
Introduction
The use of the term "Cloud" has been thrown about for a few years now, and I'm sure all of you now understand to some level what it means, and how you are able to use it.
There may however be some uncertainty on when and where to use it best, as well as detailed knowledge of the various offerings available, which keep changing at such a drastic rate. Books or documents you may have read a year or two ago about service offerings would more than likely have become obsolete now.
My intention is to write a series of articles explaining various aspects of Cloud Technologies. This article, being the first in the series, will focus on the basics defining what Cloud is and will try to explain the various types of cloud technologies available on a high level.
Future articles will focus on how you as a business can benefit from using such Cloud Technologies by comparing some of the top offerings available in the industry.
Please do feel free to get in touch if you have any thoughts on this article or suggestions on what you would like to read next in more detail.
Cloud Explained
The diagram below tries to explain Cloud in a simplified manner. Cloud providers host applications and infrastructure within their own data centres. Then rather than restricting management access for these systems to just the IT department, access is granted directly to the users and developers through the cloud interface. The users and the developers see the cloud interface with specific controls to create and modify new applications and infrastructure on demand.
Figure 1: What is cloud?
Once created, you as users or developers only have to worry about configuration of those applications and infrastructure. All the behind the scenes technical aspects of setting them up like the data centre capacity, power, cooling, rack space, cabling, storage structure, backups, resilience etc are taken care of by the cloud providers and no longer your problem as a user or developer.
The biggest advantage of this approach is that you the user don't need to worry about the huge upfront infrastructure costs of setting the environments up. This usually also includes operating system and other license costs depending on the type of cloud you've chosen. Cloud technologies therefore give businesses a vast reduction in CAPEX and a more controlled OPEX spend [1].
All you get is a monthly bill corresponding to the size and duration of the service you consume. For example, a large server used for 5 days will cost more than a small server used for the same duration. Likewise, a large server used for 10 days will cost more than a large server used for 5 days. You get the picture!
IaaS vs PaaS vs SaaS
You may also have come across these three terms - Infrastructure as a Service (IaaS), Platform as a Service (PaaS) and Software as a Service (SaaS). Let me try to explain the differences between these three terms.
IaaS: If the cloud provider in Figure 1 is hosting the infrastructure only (servers, storage, networks), and all the components hosted on this infrastructure (such as the databases, middleware and applications) are individually set up on the servers by the user, then it is an Infrastructure as a Service. An example of an IaaS provider is Amazon Web Services (AWS) that allows you to set up a virtual machine instantly and grants you access to install whichever applications you wish on those servers.
Please note AWS also offers PaaS and SaaS offerings as well as the IaaS offerings.
PaaS: If the cloud provider has also included databases, communication tools and other middleware components allowing you to develop your own applications using the tools available, it is classed as a Platform as a Service. An example of a PaaS is Azure Machine Learning, where the machine learning platform can be used to develop applications using the services provided.
SaaS: If the cloud provider gives you access to the application as a whole, and no development is necessary by the user, it is classed as a SaaS. Examples of this type of cloud are Google Mail or Dropbox.
Public vs Private vs Hybrid Cloud
So what is the difference between a public cloud and a private cloud? The main difference lies in the ownership of the data centres used to host the cloud services as shown in Figure 1. It is a public cloud if the cloud provider uses their own data centres that you (as an organisation) DON'T pay for. If on the other hand, you are hosting the cloud services yourself in your own data centres (and your organisation pays for all the upfront costs of hardware, licenses etc), BUT offer the cloud interface as an easier way for internal users to configure / manage their IT, then it is a private cloud. In a private cloud, the costs of hosting the services within the data centres is also your organisations problem, but individual users within your organisation still benefit from all the on demand characteristics of a cloud environment.
Public clouds offer the benefit that data centre operations, backup, resiliency, security are all managed as part of the service offered by the 3rd party public cloud provider. You as a consuming organisation needs to pay a monthly figure based on the usage, and don't have to worry about any of the behind these scenes activities. The down sides are that you won't have control over your data and applications, you will have to trust the maturity and capabilities of the data centre hosting provider - which is not always a bad thing! You also may not have too much control over specific configurations that you may need for your environment. For example, if you need an odd configuration such as multiple VLANs tagged to the same server in a multi-network setup, you'll find it difficult with many cloud providers.
Private cloud on the other hand is more secure since you know exactly where and how the applications and data are hosted. In fact you are even responsible for the data centre and hosting aspects of the cloud. The downside to this of course is that you have to manage the data centre costs yourself too including all the extra management headaches of performing the backups, resiliency, hardware support, licensing etc. You will also need to size the private cloud correctly knowing the exact pipeline and adoption you are likely to have in the near future, to avoid unnecessary spend.
A hybrid cloud is a scenario where you have a mixture of both public and private cloud architectures in your enterprise. This allows you to make the most of both forms of cloud in situations where appropriate.
Conclusion
I hope that this article has been able to give you a basic understanding of what cloud is and what the differences are between the various types of cloud technologies that are talked about in the industry.
Please feel free to read some of the referenced articles which may also help further develop your understanding of Cloud Technologies.
I look forward to hearing your views and ideas for future articles.
Further reading
- Rackspace, "Getting on the Right Side of the CAPEX VS. OPEX Divide", 2012, http://www.rackspace.co.uk/sites/default/files/whitepapers/wp_capexopex.pdf
- HP, "Five Myths of Cloud Computing", June 2014, http://h20195.www2.hp.com/V2/getpdf.aspx/4AA3-4550ENW.pdf
