?在Blog上看到一篇文章篇《4 Causes Of Cloud Bill Shock》，覺得有些新意，有必要Mark一下。

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# 失控的虛擬機(Runaway VMs)

方便的self-service和scaling，有可能導致啟動過量的Virtual Machine。

One of the key tenets of the cloud is self-service, making it easy for users to gain access to compute power wherever and whenever they need it. Often what happens, though, is users are so empowered to spin up compute resources that they overprovision or go over budget because there are no guidelines or caps in place to limit their usage.

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# 僵尸虛擬機(Zombie VMs)

僵尸虛擬機，也許你無法感知它的存在，它卻一直在花著你的錢。

This is something Zabrowski refers to as the "living dead" concept. Think back to the group of developers who spun up a bunch of clouds for load testing, which they never brought down, or even a handful of licenses for a software-as-a-service (SaaS) application purchased on credit cards by a lone business group, which after a period of brief usage lies dormant. While individually these expenses may not account for much, cumulatively they can add up, especially if there's no visibility for tracking, and months, even years, go by without turning off the spigot.

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# 錯誤的定價模式(Choosing the wrong pricing model)

仔細衡量一下你的Pricing Model，也許你能省些錢錢。

Cloud providers price their services differently and often, the costs are a moving target. Many organizations will opt for more expensive on-demand pricing because they don't want to make a long-term commitment to the provider, but they do so without having the proper context. "By having enough information on how long the application will be running and which users are accessing it, you could potentially take a long-term commitment, get dedicated resources, and pay a lower price. But [without proper visibility], you don't know that," Cloudyn's Wagner said.

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# 維護成本 (Maintenance costs)

維護成本并不一定會降低。

A move to the cloud means support and maintenance comes off of IT's plate. Well, that's the idea, but not necessarily the reality. "People think a move to the cloud cuts maintenance costs by 50%, but they're wrong because you still have some servers and resources that need to be supported," Wagner said. Also, all of the groups that have tapped cloud resources on their own (so-called shadow IT) come calling on IT, not the support folks at the Amazon cloud, when something goes wrong.

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# References

4 Causes Of Cloud Bill Shock

http://www.informationweek.com/news/cloud-computing/software/240001065

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小心，Cloud可能帶來沒有預料到的成本