Persistent Data Layout in File Systems

Data layout in a file system is the organization of data stored in external storages. The data layout has a huge impact on performance of storage systems. We survey three main kinds of data layout in traditional file systems: in-place update file system, log-structured file system, and copy-on-write file system. Each file system has its own strengths and weaknesses under different circumstances. We also include a recent usage of persistent layout in a file system that combines both flash memory and byte-addressable non-volatile memory. With this survey, we conclude that persistent data layout in file systems may evolve dramatically in the era of emerging non-volatile memory.