Grid vs Clouds? Who can tell the difference?

By Sinisa Veseli

The term "cloud computing" seems to be attracting lots of attention these days. If you google it, you'll find more than half a million results, starting with Wikipedia definitions and news involving companies like Google, IBM, and Amazon. There is definitely no shortage of blogs and articles on the subject. While reading some of those, I've stumbled upon an excellent post by John Willis, in which he shares what he learned while researching the "clouds".

One interesting point from John's article that caught my eye was his regard of virtualization as the main distinguishing feature of "clouds" with respect to the "old Grid Computing" paradigm ("Virtualization is the secret sauce of a cloud."). While I do not disagree that virtualization software like Xen or VMware is an important part of today's commercial "cloud" providers, I also cannot help noticing that various aspects of virtualization were part of grid projects from their beginnings. For example, SAMGrid, one of the first data grid projects that served (and still serves!) several of Fermilab's High Energy Physics experiments since the late 1990's, allowed users to process data stored in multiple sites around the world without requiring users to know where the data will be coming from, and how will it be delivered to their jobs. In a sense, from physicist's perspective experiment data was coming out of the "data cloud". As another example, "Virtual Workspaces Service" has been part of the Globus Toolkit (as incubator project) for some time now. It allows an authorized grid client to deploy an environment described by the workspace metadata on a specified resource. Types of environments that can be deployed using this service range from atomic workspace to a cluster.

Although I disagree with John's view on the differences between the "old grid" and "new cloud" computing, I still highly recommend the above mentioned article, as well as his other posts on the same subject.