| With the rapid development of information technology and the rapid growth of mass and data types of corporate data, the trend of information explosion grows significantly. The preservation of these massive data causes a serious problem of energy of data center and backup storage center, and also brings more pressure to network bandwidth. Currently Massive backup data are stored in storage center, in which a lot of redundant data exist for various reasons, such as the existence of a large number of similar duplication data in a number of total and incremental backup data and the archive data stored in different versions, which result in that duplication data leads volume of backup data to grow exponentially. Elimination of redundant data appears to be an effective technique to reduce the amount of physical storage of backup data and network transmission capacity, while an effective implementation of redundant data elimination technology is to encode similar data through the DELTA compression mechanism so as to reduce the amount of occupied space of data storage.This thesis analyses the Greedy algorithm and the SinglePass algorithm basing on thought of DELTA algorithm, and then the author proposes an Encode-Correction technology which is applied in the Single-Pass algorithm to design a Correct-SinglePass algorithm. Then the author designs and implements a backup module basing on the thought of DELTA compression, according to the strategy in today's disaster backup and recovery systems, which is mainly implemented in the client, the core algorithm of the backup module is the Correct-SinglePass algorithm. The author also designs some policies of managing, deleting and storing files for the module in this thesis.The test results show that the Correct-SinglePass algorithm owns linear running time, significant encoding compression for the database file and nearly optimal compression ratio as the Greedy algorithm, as well as the characteristic of adapting to compress large data files. DELTA compression module applied the Correct-SinglePass algorithm compresses in the client, which would greatly reduce the burden of the server and can produce smaller compressed files than the traditional method does, so that you could save storage space and reduce the occupied bandwidth of the link better and improve the efficiency of database backup and archiving more greatly. |
