Efficient Snapshot Of Hybrid Storage System

Traditional data protection techniques are designed with HDD, and not optimized for newly appeared SSD, which greatly reduces SSD performance. To make full use of high performance SSD and high capacity HDD, in this paper an efficient snapshot system is designed based on SSD/HDD hybrid storage architecture. In this system, SSD and HDD are separately deployed in application system and backup system, working parallel to meet different storage demands. SSD is for high performance application I/O, and HDD is for high capacity history I/O backups. Application system separates from backup system work, and coordinates with each other by cache synchronization mechanism. Cache synchronization is designed based on token algorithm. Application I/O consumes token, and backup I/O creates token. When all tokens are used up, application is blocked until backup operation achieved. For SSD performs much better than HDD, in this paper multiple HDDs are organized to match one SSD, eliminating HDD bottleneck. In order to provide flexible backup, in this paper different snapshot solutions such as mirror and CDP with linked metadata are proposed. Data distribution and scheduling algorithm are also proposed with each design. In the end of the paper, the system reliability was checked. Result shows even with full loads the system performance jitter is within 15%, and synchronization mechanism takes effect. Performance experiment result shows the system average IOPS is twice as traditional designs.