To flexibly meet users’ demands in cloud computing, it is essential for providers to establish the efficient virtual mapping in datacenters. Accordingly, virtualization has become a key aspect of cloud computing. It is possible to consolidate resources based on the single objective of reducing energy consumption. However, it is challenging for the provider to consolidate resources efficiently based on a multiobjective optimization strategy. In this paper, we present a novel migration algorithm to consolidate resources adaptively using a two-level scheduling algorithm. First, we propose the grey relational analysis (GRA) and technique for order preference by similarity to the ideal solution (TOPSIS) policy to simultaneously determine the hotspots by the main selected factors, including the CPU and the memory. Second, a two-level hybrid heuristic algorithm is designed to consolidate resources in order to reduce costs and energy consumption, mainly depending on the PSO and ACO algorithms. The improved PSO can determine the migrating VMs quickly, and the proposed ACO can locate the positions. Extensive experiments demonstrate that the two-level scheduling algorithm performs the consolidation strategy efficiently during the dynamic allocation process.

Elasticity is the key technique to provisioning resources dynamically in order to flexibly meet the users’ demand. Namely, the elasticity is aimed at meeting the demand at any time. However, the aforementioned approaches usually provision virtual machines (VMs) in a coarse-grained manner just by the CPU utilization. Actually, two or more elements are needed for the performance metric, including the CPU and the memory. It is challenging to determine a suitable threshold to efficiently scale the resources up or down. In this paper we present an elastic scaling framework that is implemented by the cloud layer model. First we propose the elastic resource provisioning (ERP) approach on the performance threshold. The proposed threshold is based on the Grey relational analysis (GRA) policy, including the CPU and the memory. Secondly, according to the fixed threshold, we scale up the resources from different granularities, such as in the physical machine level (PM-level) or virtual machine level (VM-level). In contrast, we scale down the resources and shut down the spare machines. Finally, we evaluate the effectiveness of the proposed approach in real workloads. The extensive experiments show that the ERP algorithm performs the elastic strategy efficiently by reducing the overhead and response time.

Cloud computing is becoming an urgent technology in the enterprises. One key characteristic in the cloud computing is the elasticity. Then, it is urgent for the users how to rank the renting services reasonably. Considering the main features of the elasticity, this article gives classification on resource optimization. However, one of the major challenges is how to optimize resource allocation in an elastic manner. Due to the special pay-as-you-go manner, resource optimizing strategies are associated with the goal of minimizing the costs on the premise of service-level-agreement (SLA). Another challenge of resource optimizing strategies is to how to dynamically respond to the application demands. In this paper, the authors sketch the elastic definition more clearly. Secondly, different dimensions are described on elastic resource allocations. Thirdly, it is important to seek out the proper resource allocation strategy. Finally, the challenges and conclusions are discussed in this article.

With the development in the Cloud datacenters, the purpose of the efficient resource allocation is to meet the demand of the users instantly with the minimum rent cost. Thus, the elastic resource allocation strategy is usually combined with the prediction technology. This article proposes a novel predict method combination forecast technique, including both exponential smoothing (ES) and auto-regressive and polynomial fitting (PF) model. The aim of combination prediction is to achieve an efficient forecast technique according to the periodic and random feature of the workload and meet the application service level agreement (SLA) with the minimum cost. Moreover, the ES prediction with PSO algorithm gives a fine-grained scaling up and down the resources combining the heuristic algorithm in the future. APWP would solve the periodical or hybrid fluctuation of the workload in the cloud data centers. Finally, experiments improve that the combined prediction model meets the SLA with the better precision accuracy with the minimum renting cost.

Cloud computing is becoming an urgent technology in the enterprises. One key characteristic in the cloud computing is the elasticity. Then, it is urgent for the users how to rank the renting services reasonably. Considering the main features of the elasticity, this article gives classification on resource optimization. However, one of the major challenges is how to optimize resource allocation in an elastic manner. Due to the special pay-as-you-go manner, resource optimizing strategies are associated with the goal of minimizing the costs on the premise of service-level-agreement (SLA). Another challenge of resource optimizing strategies is to how to dynamically respond to the application demands. In this paper, the authors sketch the elastic definition more clearly. Secondly, different dimensions are described on elastic resource allocations. Thirdly, it is important to seek out the proper resource allocation strategy. Finally, the challenges and conclusions are discussed in this article.