The Composite-File File System: Decoupling The One-To-One Mapping Of Files And Metadata For Better Performance

Traditional file system optimizations typically use a one-to-one mapping of logical files to their physical metadata representations. This mapping results in missed opportunities for a class of optimizations in which such coupling is removed.We have designed, implemented, and evaluated a composite-file file system, which allows many-to-one mappings of files to metadata, and we have explored the design space of different mapping strategies. Under webserver and software development workloads, our empirical evaluation shows up to a 27% performance improvement. This result demonstrates the promise of composite files.