We Ain't Afraid of No File Fragmentation - Causes and Prevention of Its Performance Impact on Modern Flash SSDs

Explore a groundbreaking conference talk from FAST '24 that challenges conventional wisdom on file fragmentation in modern flash solid-state disks (SSDs). Delve into a comprehensive investigation of fragmentation-induced performance degradation across kernel I/O paths, host-storage interfaces, and flash memory accesses. Discover why die-level collisions, rather than request splitting, are the primary culprit behind performance issues. Learn about an innovative NVMe command extension and page-to-die allocation algorithm designed to mitigate these problems without resorting to defragmentation. Examine the results of evaluations conducted with commercial SSDs and an SSD emulator, showcasing the effectiveness of this new approach in maintaining read performance even in highly fragmented scenarios. Gain insights from this award-winning research that promises to revolutionize our understanding and management of file systems on modern SSDs.