Cloud Computing makes it possible for providers to quickly deploy and scale services and obtain benefit from pay-by-use models under low cost, while users enjoy the flexibility of Internet-based computing services. Users find it difficult to fully trust cloud-based services because cloud-based data storage and protection methods are largely user transparent. In the early stages of cloud security there is no universal model or set of techniques has yet emerged. It includes method of segregating user resources during data processing. It is also necessary to optimize the resource cost. With the reservation plan, the consumer can reduce the total resource provisioning cost.