What is Cloud Computing?

Posted by R1Soft on Mar 2, 2010 11:32:00 AM


Everywhere I look it seems I see the term "cloud computing." Amongst insiders in the hosting industry “the cloud,” has become an inside joke. I think we all know that, as a buzzword, “cloud” is nearly meaningless.

And while the word “cloud” may be meaningless it is giving the hosting industry a fresh coat of paint and much needed hype, boosting the sales of hosted services. It may well be a cause for celebration across the hosting industry. It has grown-up. It's ready for prime time.

One thing for sure, the word “cloud” has done wonders to get the investment community excited about hosting and this appears to have improved the valuations of almost any businesses that sells products or services “in the cloud.” Who can complain about that (especially if you are a shareholder of one of those companies)?

I am going to attempt to define “cloud computing.” Not as it should be but instead as it is actually used. You may not like my answer. I appreciate your feedback. I’m not sure if it’s even possible to define cloud computing definitively. Still, I am going to attempt it.

Perception of Cloud Computing

When you think of Cloud Computing, you likely come up with one or more of the following ideas:

  • Utility
  • Self-healing
  • Grid
  • Elastic
  • Scalable
  • Cluster
  • Virtualization
  • Maybe brands like: EC2 / S3 / Nirvanix / GoGrid / VPS.net / RackSpace

Cloud Computing Defined – Here You Go

Cloud computing is any hosted service over the Internet.

Cloud services typically fit into one of these boxes:

  1. Software as a Service - examples: Salesforce.com, WordPress.com, eClinicalWorks
  2. Storage as a Service - examples: Nirvanix, Amazon S3
  3. Platform as a Service - examples: Amazon EC2, Rackspace Cloud, VPS.net, GoGrid

What Cloud Computing May or May Not Be

Cloud computing may or may not be any combination of these:

  • Reliable
  • Self-Healing (fail-over)
  • Scalable
  • Virtualized
  • Use a Grid
  • Elastic
  • Clustered

That means when you are shopping for a service in "the cloud,” you need to do your homework. Do not just assume because it is labeled a "cloud offering" that it has some magical powers.

There are cloud services that have fail-over capabilities, are very reliable, and very scalable. That does not mean they all live up to those standards.

A Brief History of the Cloud

I think it is easier to see through the word cloud if we just use a little bit of history and break it down into digestible bites.

Virtual Hosting

It seems we started out with this idea of virtual hosting. Sharing an expensive Internet server among multiple users or customers as a way to sell needed hosted services to people that could not justify a dedicated Internet server. We used the Apache web server, MS IIS, PHP, ASP, and Bind DNS to cram as many web sites and web applications on a server as possible.

Management Software for Shared Services

Then all of a sudden people realized that sharing their computing resources with strangers can be a problem for three obvious reasons:

  1. Management (mostly a service provider problem)
  2. Security
  3. Sharing limited hardware resources (CPU, memory, disk)

Soon there were software applications to manage the virtually hosted web sites and they came from vendors like CPanel and Plesk. They solved the management issue and helped some with security.

Virtual Private Servers

Then a new platform for hosting services came along called a Virtual Private Server from vendors like Sphera and Parallels Virtuozzo. These products added more solid security to the mix and helped a little with the sharing of hardware resources.


Enter Citrix XenServer.  Xen is the dominant platform for services hosted in the cloud that use virtualization.  It solves the security problem, the hardware sharing problem and it does it all with pretty darn good performance*. Xen probably does not really solve the manageability problem yet… that’s OK… the hosting providers are solving that on their own.

If you have a service in the cloud that uses a virtual machine or virtual private server, chances are it’s on the Xen Virtualization platform.

What about VMWare, I thought VMWare was virtualization?

Yes VMWare was probably the first to solve the virtualization problem and gain mass market share. VMWare solves all three problems: manageability, security, and sharing hardware. VMWare did not find its way into the cloud so much. The reason is that VMWare is not priced in a way that cloud, I mean hosted service providers can make a profit after paying for licenses of VMWare. Of course there are some providers using it, some even extensively… true. Overall use of VMWare in the cloud is very small in my humble opinion and will likely continue to remain so as long as Xen is provided basically free of charge. 

* I say Xen has good performance with the caveat that so far, sharing hardware has some pitfalls no matter how you do it… that is for another post.


Since cloud computing is just a hosted service delivered over the Internet most people in some way are already a customer of some type of cloud service.  Have a web site hosted?  You already use the cloud.  Have a blog account on Wordpress.com? Use salesforce.com? You have a cloud service.

So while “the cloud” is nothing new, there are some new developments in the technology used to deliver hosted services.

See also:


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Topics: hosted services, cloud, hosting industry, cloud services, cloud computing, virtualization, xen

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