Resources have different availability and costs in the cloud, and the models don't yet reflect that variation Capacity management is all about creating a plan assuring the business there will be just enough volume (servers, storage, network, and so on) for critical applications and data when needed. This means creating complex performance and power models to make sure you’re neither spending too much nor too little money on IT infrastructure.But what changes for capacity management in the emerging world of cloud computing? A few things come to mind. You can no longer assume that computing capacity is dedicated to a group of users or a group of processes. Everything in a cloud computing environment is shared using some sort of multitenant model. This complicates capacity modeling and planning. With autoprovisioning, some aspects of capacity planning decrease in importance because capacity can be allocated as needed. However, because cost is a core driver for the use of cloud computing, using capacity that’s not needed reduces the cloud’s value. You can use cloud computing systems as needed to cost-effectively provide temporary capacity. Called “cloud-bursting,” the cost of this type of architecture has been difficult to justify until cloud computing provided a cheaper “public” option.The bad news: Cloud computing providers and the use of cloud computing in enterprises will make the process of capacity planning much more complex. The modeling approaches and technologies are changing to accommodate these added complexities, but many capacity-planning professionals need to update their skills. The good news: Cloud computing providers will provide more performance and capacity monitoring and management services as time goes on. Their users are demanding them, so those charged with managing capacity and performance will have better interfaces for their tools.This article, “How capacity management changes in the cloud,” originally appeared at InfoWorld.com. Read more of David Linthicum’s Cloud Computing blog and track the latest developments in cloud computing at InfoWorld.com. For the latest business technology news, follow InfoWorld.com on Twitter. Cloud ComputingCareers