Direct lookup and hash-based metadata placement for local file systems

New challenges to file systems' metadata performance are imposed by the continuously growing number of files existing in file systems. The total amount of metadata can become too big to be cached, potentially leading to multiple storage device accesses for a single metadata lookup operation. This paper takes a look at the limitations of traditional file system designs and discusses an alternative metadata handling approach, using hash-based concepts already established for metadata and data placement in distributed storage systems. Furthermore, a POSIX compliant prototype implementation based on these concepts is introduced and benchmarked. A variety of file system metadata and data operations as well as the influence of different storage technologies are taken into account and performance is compared with traditional file systems.

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