Adaptive Replica Management for Large-scale Object-based Storage Devices

Replica management is basic and challenging issue for distributed storage system designer. The objective of this paper is to dynamically create, migrate and delete replicas among nodes in response to changes in the access patterns. This paper presents an Adaptive Replica Management Model for large-scale Object-based Storage Devices (OSDs). The model expresses availability and consistency maintenance cost as functions of replica number and suggests lower bound and upper bound on replica reference number based on file availability requirement and available network bandwidth. The model can adapt to the changes of environment and maintains a rational number of replica, which not only satisfies object availability, improves access efficiency and balances overload, but also reduces bandwidth requirement and keeps the whole storage system stable. Our experimental evaluation results demonstrate that our model can perform well for system reliability and performance.