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The Illusion of Unlimited Capacity

By: Andy Troup 

I was at a customer workshop last week, and I used a phrase that I’ve used a few times to describe one of the crucial capabilities of a successful cloud computing service, namely “The Illusion of Unlimited Capacity.” It got a bit of a reaction, and people seemed to understand the concept quite easily. So apart from its sounding quite cool (maybe I should get out more), why do I keep on using this term?

Well, in cloud computing, we all know that there is no such thing as unlimited capacity – everything is finite. Every cloud provider only has a limited number of servers, a limited amount of storage capacity, and a limited number of virtual and physical network ports – you get the idea, it’s all limited, right?

Paradoxically, though, providers of cloud resources have to make sure their customers believe the opposite: that there is no end to what can be consumed.

The National Institute of Standards and Technology (NIST) defines one of the characteristics of cloud computing as on-demand self-service; i.e. the user can consume what they want, when they want it. Now, for cloud providers to provide on-demand self-service, they need to be confident that they can fulfill all the requests coming from all their consumers, immediately. They need to maintain, in other words, an illusion of unlimited capacity.

If at any point a consumer makes a request, and the cloud portal they use responds with a “NO” because it’s run out of cloud resources, this illusion has gone. That has real consequences. As it is very easy for consumers to move between cloud providers, it’s very likely that the provider will have lost them as customers and will find it very hard to get them back. Remember, even for internal IT cloud providers, it’s a competitive market place and the customer is king.

So, when defining your cloud strategy, you want to make sure that maintaining ‘the illusion of unlimited capacity’ is on your list. It may not be something you need to consider initially, but when demand for your services increases, you need to be ready to deal with the challenge. To prepare for it, here are 5 things you should start thinking about:

  • Understand your customers – build a strong relationship with your customers, understand their business plans, and use this information to understand the impact those plans will have on the demand for your cloud services.
  • Implement the appropriate tooling – so you can not only understand demand for your cloud capacity today, but also forecast future demand.
  • Consider the Hybrid Cloud – think about how you would burst services in and out of a hybrid cloud and when you would need to do it. Before you actually need to do this, make sure you plan, prepare and automate (where possible), so that everything is in place when it’s needed. Don’t wait until it’s too late.
  • Train users on service consumption etiquette – if they know they can get what they need when they need it, they will be less inclined to hoard resources. And if they aren’t hoarding resources, the pressure to predict their future demand (which can be difficult) will be reduced, because resources are being used more efficiently. Why not agree that they won’t have to plan capacity if they “turn it off” when done, thus freeing resources back to the pool and further increasing spare capacity.
  • Kill zombie workloads – be aware of services that aren’t being used and turn them off (after having a conversation with the customer). Also, encourage the use of leases for temporary services when appropriate.

Finally, going back to the essential characteristics of cloud computing as defined by the National Institute of Standards and Technology (NIST) (here is the very short document for those of you that haven’t read it), one other characteristic is rapid elasticity.

If you think about it, this article is really all about rapid elasticity. It’s just another way of saying that you need to maintain the illusion of unlimited capacity. Now, put on your top hat, hold on to your magic wand, and keep the illusion going.

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