Stupid File Systems Are Better

File systems were originally designed for hosts with only one disk. Over the past 20 years, a number of increasingly complicated changes have optimized the performance of file systems on a single disk. Over the same time, storage systems have advanced on their own, separated from file systems by the narrow block interface. Storage systems have increasingly employed parallelism and virtualization. Parallelism seeks to increase throughput and strengthen fault-tolerance. Virtualization employs additional levels of data addressing indirection to improve system flexibility and lower administration costs. Do the optimizations of file systems make sense for current storage systems? In this paper, I show that the performance of a current advanced local file system is sensitive to the virtualization parameters of its storage system. Sometimes random block layout outperforms smart file system layout. In addition, random block layout stabilizes performance across several virtualization parameters. This approach has the advantage of immunizing file systems to changes in their underlying storage systems.