星载固态存储系统自适应闪存转换层设计

传统星载存储系统闪存转换层（Flash Translation Layer, FTL）算法采用页级FTL映射方案和固定分区的文件管理策略,存在主机占用率高、系统响应时间长以及没有充分考虑FLASH磨损均衡等问题.为此,对传统星载存储系统方案和星载固态存储系统的工作原理深入分析研究,结合实际型号任务需求,提出了一种数据驱动的自适应超级块闪存转换层算法 (Data-driven Adaptive Superblock FTL, DASFTL).DASFTL算法采用自适应超级块的分级地址映射方案,其中超级块映射表（Superblock Mapping Table, SMT）作为一级映射,页地址映射表（Page Mapping Table, PMT）作为二级映射,以提高系统的响应速度；将超级块作为FLASH地址管理的最小单元,以减少存储系统对主机的依赖；引入动态块回收权重作为超级块分组和目标回收块选择的标准,以均衡FLASH芯片内各物理块的磨损程度,延长其使用寿命.搭建硬件测试平台对DASFTL算法进行验证,实验结果表明,提出的数据驱动的自适应超级块闪存转换层算法相比于传统星载FTL算法在主机占用率和系统响应速度上分别有51.7%、46.1%的提升.长时间工作下FLASH芯片内部各物理块的擦除次数更加均衡,有效避免部分物理块过早磨损,提升FLASH芯片使用寿命.

Adaptive flash translation layer design for spaceborne solid state storage systems

The traditional flash translation layer (FTL) algorithm of spaceborne storage system adopts page-level FTL mapping scheme and fixed partition file management strategy, which has many problems, such as high host occupancy, long system response time, and no consideration of FLASH wear balance. Therefore, a data-driven Adaptive Superblock FTL (DASFTL) algorithm was proposed based on the analysis of the working principle of traditional spaceborne storage system and spaceborne solid state storage system. DASFTL adopts the hierarchical address mapping scheme of adaptive superblock, in which the super block mapping table is the first level mapping and the page mapping table is the second level mapping for improving response time. The superblock was taken as the smallest unit of FLASH address management to reduce the dependence of storage system on host. Dynamic block recovery weight was introduced as the criterion of superblock grouping and target recovery block selection to balance the wear degree of the physical blocks in FLASH chip and prolong its service life. In the end, a hardware test platform was built to verify the DASFTL algorithm. Results show that compared with the traditional spaceborne FTL algorithm, the host occupancy rate and the system response time of the DASFTL algorithm were increased by 51.7% and 46.1%, respectively. The balanced wear performance of the FLASH chip was significantly improved, which can prolong the service life of the FLASH chip.