Multi-objective Optimization of Data Placement in a Storage-as-a-Service Federated Cloud

Abstract

Cloud federation enables service providers to collaborate to provide better services to customers. For cloud storage services, optimizing customer object placement for a member of a federation is a real challenge. Storage, migration, and latency costs need to be considered. These costs are contradictory in some cases. In this article, we modeled object placement as a multi-objective optimization problem. The proposed model takes into account parameters related to the local infrastructure, the federated environment, customer workloads, and their SLAs. For resolving this problem, we propose CDP-NSGAII IR , a Constraint Data Placement matheuristic based on NSGAII with Injection and Repair functions. The injection function aims to enhance the solutions’ quality. It consists to calculate some solutions using an exact method then inject them into the initial population of NSGAII. The repair function ensures that the solutions obey the problem constraints and so prevents from exploring large sets of unfeasible solutions. It reduces drastically the execution time of NSGAII. Experimental results show that the injection function improves the HV of NSGAII and the exact method by up to 94% and 60%, respectively, while the repair function reduces the execution time by an average of 68%.

Review on data replication strategies in single vs. interconnected cloud systems: Focus on data correlation‐aware strategies

“…69 When a replication strategy is centralized, a central authority controls all aspects of replication. 39,58,65,[70][71][72] Decentralized replication strategies encourage no central control. These strategies are more effective in responding to system changes and dealing with failures and outages situations.…”

“…These issues are important because they influence task execution time, storage space usage, network usage and so forth. 20,27,59,61,63,64,72,83,86 Interconnected cloud strategies are more focused on the replicas placement issue since they decide replica locations among the available resources of multiple cloud providers.…”

“…This results in increasing the profit for the provider. 20,63,64,72,73,75,118 Most of the replication strategies are oriented towards the provider since they consider the provider to be the entity responsible for the replication process. Only a few strategies are consumer-centric.…”

“…20,30,63,118 Provider-centric strategies in the interconnected cloud environments focus mainly on taking advantage of the differences between the pricing policies of the cloud providers among each other to reduce the cost of management. 40,66,72,73,75,101…”

“…Economic cost models are generally related to the economic aspect of the cloud, including the pricing policies, the monetary cost of management, auctions and so forth. 20,30,40,64,66,72,73,78,90,91,118,122,133 The focus on the economic aspect of cloud systems by replication strategies is mainly done by addressing the monetary cost of replication. 20,30,40,64,66,72,73,78,90,91 This monetary cost is often estimated by economic cost models that take into account both the cost of data storage and data transfer as well as the cost of the SLA penalties.…”