Sometimes, I find myself wandering through a Home Depot on Saturday, and I see something that catches my eye. Perhaps a seed packet for spinach. Perhaps a new pair of garden shears. I pick it up, and decide to treat myself. Sure, they are useful. But, I’m not sure they are necessary. They are impulse purchases.

I find it hard to believe that anyone would buy cloud computing on impulse. I’ve talked to dozens of people and companies about their cloud purchases – and all are highly premeditated. Rare is the case where someone opts to burst into the cloud on a moment’s notice.  So why all this bursting? Are people not planning, even a little?

How do you plan for external public cloud usage? It’s possible. It’s being done by enterprises everywhere.

First, in the past, we’ve talked about understanding who your users are, and what services you’d like to offer.

Then, we’ve talked about estimating the capacity you’ll need to address these requests – and the onslaught of new ones you’ll get when people realize just how easy it is to get what you need from this new-fangled cloud thing.

So, how are you going to fulfill all those needs? Well, you can estimate what you have on-site by way of resources. Not enough? Think you might need more for certain times? Well, take that list of services you’re offering and categorize them as “must be in my datacenter” and “could potentially move outside.” The criteria include:

  • Compliance requirements – both operational and regulatory
  • Security requirements
  • The complexity of configuration needed
  • Proximity to large data sources (moving lots of data tends to be inefficient, both financially and practically)
  • Splotchy consumption of resources
  • The price of external resources

Having isolated the cloud services you can potentially send to the public cloud, it’s time to investigate options. My experience in the past few months is that service providers are rapidly increasing the breadth of offerings available – so this is an exercise worth repeating every few months. Map the appropriate services to your needs, and do some financial calculations with your trusty budget team to ensure you’re making sound financial decisions, and implement your plan.

Sometimes using public cloud resources is an ongoing strategy for certain workloads. Other times, it’s overflow. Either way, the time to decide is before you need it. Because we all know, you don’t make great shopping decisions on an empty stomach.

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