基于混合策略的低成本云存储方案

为了保证云存储系统数据的高可用性、降低数据存储成本和带宽成本、缩短数据对象的访问时间，提出一种称为缓存大小自适应确定(CAROM)的新方案。CAROM结合传统的基于缓存策略的方法和纠错码方法来提高云文件系统的弹性和效率。另外，为了在缓存大小及其效益间实现平衡，提出一种基于总体成本凸函数特性的自适应方法来实现缓存大小的自适应选择。在基于现实世界文件系统数据的性能评估中，CAROM方案的存储成本和带宽成本分别比复制策略和纠错码策略下降60%和43%，同时访问延时与复制策略相当。结果表明，CAROM方案在支持当前云文件系统语义一致性的同时，兼具带宽成本低、存储成本低和访问成本低等特性。

Low-cost cloud storage scheme based on hybrid strategy

To ensure the high data availability in cloud storage system, reduce the cost of data storage and bandwidth, shorten the time for accessing data objects, a new scheme named Cache A Replica On Modification (CAROM) was proposed. It combined traditional methods based on replication strategies and erasure coding strategies to improve the flexibility and efficiency of cloud file system. In addition, in order to achieve a balance between the cache size and efficiency, an adaptive method based on the characteristics of the overall cost of a convex function was proposed to select adaptive cache size. A large-scale evaluation using real-world file system was conducted, and CAROM outperformed replication based schemes in storage cost by up to 60% and erasure coding schemes in bandwidth cost by up to 43%, while maintaining low access latencies close to those in replication based schemes. The results indicate that, while maintaining the same consistency semantics seen in current cloud file systems, CAROM provides the benefit of low bandwidth cost, low storage cost and low access latencies.