Extending the lifetime of NAND flash-based SSD through compacted write

摘要

In the traditional file system, the partial page write will result in internal fragmentation and write amplification of NAND flash-based SSDs due to the page-alignment of write. Although large page sizes are useful for increasing the flash capacity and throughput, they may decrease the performance and lifetime of flash storage systems for the frequent partial page writes. After analysing the various realistic workload traces, we observe that the partial page writes are common for those heads and tails of large write requests. This observation makes compacted write possible, which compresses two partial page writes from the same large write request into one page before data are written into flash. Therefore, we propose a compacted write for page-level FTL scheme, called CWFTL, to extend the lifetime of SSD. The experiment results show that CWFTL really reduces the times of data written to flash and the average read/write response time.