Cloud Computing != Grid Computing?

Following up to a previous post, I came across a July 2008 article by Thorsten von Eicken, CTO and founder of RightScale, which provides a front-end for managing Amazon Web Services (Amazon’s cloud computing offerings):

Grid computing has been used in environments where users make few but large allocation requests. … [O]nly a few of these allocations can be serviced at a time and others need to be scheduled for when resources are released. …

Cloud computing really is about lots of small allocation requests. … The allocations are real-time and in fact there is no provision for queueing allocations until someone else releases resources. …

It’s easy to say “ah, we’ll just run some cloud management software on a bunch of machines,” but it’s a completely different matter to uphold the premise of real-time resource availability. If you fail to provide resources when they are needed, the whole paradigm falls apart and users will start hoarding servers, allocating for peak usage instead of current usage…

The comments on that post are worth reading, as well.

An earlier post from Thorsten (republished later on Cloud Computing Journal) clearly and succinctly defines some terminology used to refer to different aspects of cloud computing:

Applications in the cloud: … Some company hosts an application in the internet… The service being sold (or offered in ad-sponsored form) is a complete end-user application. To me all this is SaaS, Software as a Service, looking to join the ‘cloud’ craze.

Platforms in the cloud: … where an application platform is offered to developers in the cloud. … The service being sold is the machinery that funnels requests to an application and makes the application tick.

Infrastructure in the cloud: … the most general offering that Amazon has pioneered and where RightScale offers its management platform. … virtually any application and any configuration that is fit for the internet can be mapped to this type of service.

Again, the comments are worth reading and link to other articles on the subject.