Efficient task and workflow scheduling in inter-cloud environments: challenges and opportunities

Efficient task and workflow scheduling are very crucial for increasing performance, resource utilization, customer satisfaction, and return of investment for cloud service providers. Based on the number of clouds that the scheduling schemes can support, they can be classified as single-cloud and inter-cloud scheduling schemes. This paper presents a comprehensive survey and an overview of the inter-cloud scheduling schemes aimed to allocate user-submitted tasks and workflows to the appropriate virtual machines on multiple clouds regarding various objectives and factors. It classifies the scheduling schemes designed for a variety of inter-cloud environments and describes their architecture, key features, and advantages. Also, the inter-cloud scheduling approaches are compared and their various features are highlighted. Finally, the concluding remarks and open research challenges in the multi-cloud scheduling context are illuminated.