NAND Flash Aware Data Management System for High-Speed SSDs by Garbage Collection Overhead Suppression

Solid-state drives (SSDs) are replacing hard disk drives (HDDs) in many applications. However, SSD is slow in write performance due to the "erase-before-write" characteristics. The performance bottleneck lies in the garbage collection (GC) operation in which all the valid pages have to be copied from the erasing block to a new block This paper proposes a NAND flash aware data management system to improve the SSD performance by minimizing the GC overhead. The newly introduced intermediate layer called LBA scrambler is inserted between the file system (operating system) and the flash translation layer (FTL). The proposed LBA scrambler interacts with the FTL and intelligently recognizes the fragmentation inside the NAND flash. By actively writing new data to the fragmented pages in the next erase target block, the required copied page number during GC can be minimized As a result, 4-times SSD performance improvement, 60% energy consumption reduction and 55% endurance enhancement are achieved.