FSAF: File System Aware Flash Translation Layer for NAND Flash Memories

Abstract

NAND Flash Memories require Garbage Collection (GC) and Wear Leveling (WL) operations to be carried out by Flash Translation Layers (FTLs) that oversee flash management. Owing to expensive erasures and data copying, these two operations essentially determine application response times. Since file systems do not share any file deletion information with FTL, dead data is treated as valid by FTL, resulting in significant WL and GC overheads. In this work, we propose a novel method to dynamically interpret and treat dead data at the FTL level so as to reduce above overheads and improve application response times, without necessitating any changes to existing file systems. We demonstrate that our resource-efficient approach can improve application response times and memory write access times by 22% and reduce erasures by 21.6% on average.