Reducing the read latency of in-line deduplication file system

Yongtao Zhou, Yuhui Deng, Yan Li, Junjie Xie

Abstract: In-line dedupliaction systems mainly focus on secondary storage for backup and archiving, and just offer several simple APIs. Applications can not directly invoke these APIs without modification. Although file systems offer abundant APIs and amity to applications, building a file system for in-line deduplication brings new challenges in the I/O path. Read operations involve multiple disk accessing, which includes getting fingerprints in file recipes, obtaining the addresses by checking fingerprint index and reading corresponding data blocks in disk drive. This extremely increases the latency in read path. We present a Low-Read-Latency File System (LRLFS) for the in-line deduplication. Experiments suggest that LRLFS obtains low read latency in read path with negligible storage overhead, acceptable CPU and memory utilization rate.