FStream: Managing Flash Streams in the File System

The performance and lifespan of a solid-state drive (SSD) depend not only on the current input workload but also on its internal media fragmentation formed over time, as stale data are spread over a wide range of physical space in an SSD. The recently proposed streams gives a means for the host system to control how data are placed on the physical media (abstracted by a stream) and effectively reduce the media fragmentation. This work proposes FStream, a file system approach to taking advantage of this facility. FStream extracts streams at the file system level and avoids complex application level data mapping to streams. Experimental results show that FStream enhances the filebench performance by 5%∼35% and reduces WAF (Write Amplification Factor) by 7%∼46%. For a NoSQL database benchmark, performance is improved by up to 38% and WAF is reduced by up to 81%.