Multi-Replica Cloud Data Storage Based on Hierarchical Network Coding

The rapid development of cloud data storage presents a high demand on the availability of stored data. Currently, the main technique of ensuring data availability is to use erasure coding to calculate coded blocks for the stored data, and then utilize distributed storage to store multiple redundant coded blocks in cloud storage space. Although this data coding technology can ensure the security of stored data and reduce extra storage space, it also causes a large calculation and communication overhead when recovering corrupted data. In this paper a multi-replica generation and corrupted data recovery algorithm is proposed based on hierarchical network coding. The algorithm improves the coding matrix of erasure coding based on hierarchical network coding to form the hierarchical coding (HC). Then multi-replicas which are built based on the cascade of the hierarchical coding forms the coding relationship between each other. In the process of corrupted data recovery, the data encoding information provided by the data owner and the complete data blocks stored by the cloud server are jointly computed to recover the corrupted data blocks, avoiding remote data downloading from the cloud storage space. Theoretical analysis and simulation experiments indicate that the proposed algorithm reduces the communication overhead significantly when recovering corrupted data and improves the availability of stored data under the same storage space.