Cloud computing: State-of-the-art and future research trends

Clouds have been very popular, and their performance becomes more important due to the increase of users and applications. Currently, many enterprises are adopting Clouds to achieve high performance for their applications at low costs. Because of the nature of these systems, there are important issues that must be addressed, such as: resource allocation, efficient scheduling, energy conservation, reliability, security and trust, cost, availability, quality. Effective management of cloud resources is crucial to use effectively the power of these systems and achieve high system performance. Furthermore, software structures that best exploit clouds capabilities while providing applications compatibility should be examined. Cloud computing is a concept that has emerged from grid computing; it provides users the ability to acquire computational resources on demand from its virtually infinite pool on a pay-as-you-go basis. The cloud computing paradigm can offer various types of services, such as computational resources for HPC applications, web services, social networking, etc. Resource allocation and scheduling is a difficult task in clouds where there are many alternative heterogeneous computers. If cloud computing is going to be used for HPC, appropriate methods must be considered for allocating resources to user requests efficiently, VM scalability, as well as effectively scheduling the tasks. The scheduling algorithms must seek a way to maintain a good response time to leasing cost ratio. Furthermore, adequate data security and availability are critical issues that have to be considered along with energy-efficient solutions that are required to minimize the impact of cloud computing on the environment.