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.
data layout; file system; persistent storage; solid state drive (SSD)