Cloud is an operations model, not technology

One of the most common questions I get from those exploring cloud computing for the first time is "what is the difference between cloud computing and virtualization?" It is an excellent question, as most IT departments are currently exploring the ways in which virtualization enables automation and provisioning agility. Given the fact that cloud is often touted for providing similar benefits, it can be confusing to understand why the two terms aren't equivalent.

My response to that question requires a bit of explanation, so let's step through the differences between the two concepts.

Virtualization is a technology.

(Credit: CNET/James Urquhart)

When you run software in a virtual machine, the bits that represent the program's instructions run through a layer of software that "pretends" to be a dedicated server infrastructure, the hypervisor. The hypervisor is the heart and soul of server virtualization, and is the enabler of the consolidation and agility values that virtualization brings to the data center.

It is because of the hypervisor that virtualization is the true disruptive technology that enables cloud computing on a massive scale. Hypervisors allow servers to be multi-tenant without rewriting applications to be multi-tenant. Hypervisors allow operating systems and applications to install to a consistent hardware profile, even though they end up running on a variety of actual physical system implementations. Hypervisors also allow servers to be manipulated by software APIs, which greatly simplifies the act of automating IT operations.

Cloud computing is an operations model, not a technology.

When you run an application in a public or private cloud, there is no "cloud layer" that your software must pass through in order to leverage the physical infrastructure available to it. In the vast majority of cases, there is probably some virtualization involved, but the existence of hypervisors clearly does not make your data center resources into a cloud. Nor is the fact that Amazon EC2 uses Xen hypervisors the reason that they are a cloud.

What makes a cloud a cloud is the fact that the physical resources involved are operated to deliver abstracted IT resources on-demand, at scale, and (almost always) in a multi-tenant environment. It is how you use the technologies involved. For the most part, cloud computing uses the same management tools, operating systems, middleware, databases, server platforms, network cabling, storage arrays, and so on, that we have come to know and love over the last several decades.

Specific technologies, of course, gain significant importance in a cloud computing environment, such as policy-driven automation, metering systems, and self-service provisioning portals. However, all of these technologies--with the possible exception of the self-service portal--existed before cloud computing became a much hyped paradigm.

There is no doubt cloud borrows much from long established technologies. It is also true that cloud has borrowed from many long standing operations models, such as mainframe service bureaus. However, the combination of on-demand, at scale, in a multi-tenant infrastructure is relatively unique for the post client-server era, and is the reason why cloud computing is disruptive, rather than just another operations fad.

[dannymjohnson]

Since moving my documents management to the cloud using NetDocuments.com, I've been able to enjoy all the benefits you described and more. I have sinced been trying to move everything I do to the cloud.

[kuchnakaho]

You are missing grid computing as just another important layer. At the core of cloud computing is grid computing that provides resource overflow and eventually scalability to the cloud.

[jamesurquhart]

That particular definition of "grid computing" is what I call policy-based automation. And, again, it doesn't sit in the execution stack, but sits to the side in the management stack. Of course, I'm sure you'd agree that there was grid computing before there was cloud computing.

[bertarmijo]

I don't often disagree with you, but this is going to have to be one of those time James.

Cloud computing turns traditional data centers inside out. Infrastructure like networks, storage, and policies which have been shielded not only from the public but from developers as well, are now exposed as a service layer - that IS the cloud. Whether using the EC2 approach of shared infrastructure accessed via API or the 3tera approach of dedicated infrastructure created on-demand, cloud data centers are designed to respond to application requests. That response layer is definitely new technology.

[jamesurquhart]

Bert,

I didn't say that there wasn't new technology involved, just that the technology supports an operational model, and doesn't become a part of the machine/application interface. Java doesn't have to be rewritten to run in the cloud, nor does SAP, nor does anything else, assuming it isn't tightly coupled to a single infrastructure.

Unless you are saying that your platform (3tera) forces developers to rewrite applications to be aware of and in control of infrastructure usage (which I am *sure* you are not), then your platform is monitoring application needs and responding on its behalf. In other words, 3tera does an excellent job of automating the operation of the application, without effecting its execution.

Cloud computing management systems are tools to support the cloud model. Virtualization management systems are tools to support virtualized technology. I hear what you are saying, but I stand by my assertion.

[Tom-From-Facebook]

Great article. Precisely to the point! Cloud, like Outsourcing before it, is an operations model, not a new technology. It's a new variation of outsourcing model to some degree. Our IT dept tried VMWare, but it requires too much IT support and expertise. When we found Amazon EC2, it's great. IT loves it (a minimum support is required), and more important, internal users love it since they don't have to beg IT to support them. Amazon EC2 is simple and powerful enough at the same time.

[ReedSmith]

You hit the nail on the head here. Hyper-visor based virtualization enables most clouds, but you don't have to have a hyper-visor to get many cloud benefits. Virtualization is great for some workloads. It enables some great features like a instant provisioning, cloning, snapshots and failover. There are some tradeoffs with virtualization around resource contention, performance bottlenecks, security concerns and latency.

Many people think they are forced to accept these tradeoffs for their virtualization unfriendly workloads to get the benefits of cloud computing. IronScale is a product that delivers the automation, flexibility and control of the cloud through a web GUI with the security and performance of dedicated physical servers. Now is it a cloud computing offering? Depends on your definition of cloud, which seems to be a pretty broad space to some these days . . . .

Reed
www.stratascale.com

[Benigna-Marko]

Everything that requires a tradeoff can't be all that good. Perhaps clouds are not the fluffy white floating water filled things over our head. You know below the sky, above the ground.
Benigna Marko

[xim1970]

"What makes a cloud a cloud is the fact that the physical resources involved are operated to deliver abstracted IT resources on-demand, at scale, and (almost always) in a multi-tenant environment."

I'm sorry, but I used to check CNET for useful information to the "tech-savvy", and I'm pretty damn "tech-savvy", but this whole article must have been written for the "techno-geeks". I understand the idea behind cloud computing (putting applications on a server, open to anyone to access and save work to), but, seriously, couldn't the author have put it that way? Probably not the type of column I should be reading anyway. Guess I'm not ready to have someone of average intelligence insult mine by being "techno-wordy".

[OtherHand]

techno-geek decoder ring:

abstracted = acts like a physical resource but isn't = virtualized
on-demand = you get in and get more without having to build it yourself, just ask (and pay)
at scale = can handle hundreds to millions of users (example: busy public websites)
multi-tenant = more than one person or company runs their stuff in it

Must admit, the geek-speak is briefer. If it's exotic or obscure enough, perhaps the vendor can charge more?

[OtherHand]

On demand, check. At scale, sure, but how big is big enough? Multi-tenant, far from essential.

2 to 5x real-world cost advantage...if not, why bother?

[loving9]

Could it be that small and midsize companies understand cloud computing better than told the crowd that "the cloud is not a technology, it's a self-service is a technology, cloud computing is an operations model

Angelina Jacob
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