关键词: CDP, 快照, 元数据文件, 时间戳, 存储空间, 函数极值

Abstract: In traditional block-level continuous data protection, in order to reduce the time of traversing metadata records and speed up the recovery, it usually needs to insert snapshots of the protected volumes periodically. Frequent insertion of snapshots increases the speed of recovery and the storage space. An improved snapshot method, MS-CDP, which adds sequence index number, pointer of the previous item and pointer of the latter item in the metadata record, is proposed for the traditional snapshot method with large storage space. When a snapshot needs to be inserted, it is not necessary to retain the complete mapping table at the current moment. By the function of the timestamp and the block number, it only needs to retain the mapping table items corresponding to the extremum. It is proved by experiment that this method significantly reduces not only the storage space of the snapshot, but also the storage pressure on the service end of CDP system.

Key words: CDP, snapshot, metadata file, timestamp, storage space, function extremum