OpenSSD platform simulator to reduce SSD firmware test time

Recently, NAND flash memory is widely used as storage media in various devices such as SD card, USB memory, and solid state drives (SSDs). NAND flash memory has different characteristics from hard disks, and thereby a firmware called flash translation layer (FTL) should be deployed to use traditional file systems on NAND flash memory. Because FTL majorly determines performance and stability of NAND-based block devices, various FTL schemes have been developed. However, their efficiency has been evaluated via simulation not on a real device, which restricts the reliability of the results. Recently, OpenSSD platform, which allows implementing a new FTL scheme on real NAND devices, was developed. By using it, evaluating the FTL performance on real NAND devices becomes possible. The problem is that it is difficult and time consuming to debug the new FTL on the OpenSSD platform. In order to address this, we design an OpenSSD simulator that helps find the bugs of FTL and reduces the test time. The FTL developed on the simulator can be migrated to the OpenSSD platform without additional porting.