Sometimes, colocating is less expensive and more effective for some applications than choosing a cloud. Colocation involves purchasing and managing hardware independently at a third-party site. One example for which this is true is the maintenance and operation of long-running databases. Overall, the cost of the hardware, the power, and the bandwidth required for colocation must be evaluated against the cost of the long-term fees for cloud usage.
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http://gigaom.com/2013/12/07/want-to-reduce-your-cloud-costs-70-percent-heres-how/