BirdStore: Block-grained snapshot management system for instant disaster recovery

Block-grained snapshot management is a requirement for emerging instant disaster recovery systems that generally use on-demand data fetching strategy. This paper presents BirdStore, an efficient block-grained snapshot management system. Block-grained snapshot version is difficult to organize due to multiple disk IOs that are needed to query the snapshot version of each block. BirdStore reduces disk IOs by grouping blocks sharing the same backup history into a segment. Thus disk IOs are issued once per segment instead of once per block. Evaluation shows that BirdStore´s algorithm is 33.5 times faster than the existing algorithm, and is very storage-efficient.