Cached Mapping Table Prefetching for Random Reads in Solid-State Drives

Xiaojun Ruan, Xunfei Jiang, Haiquan Chen

Abstract: Data caching strategies and Garbage Collection on SSDs have been extensively explored in the past years. However, the Mapping Table cache performance has not been well studied. Mapping table provides page translation information to Flash Translation Layer (FTL) in order to translate Logical Page Address (LPA) to Physical Page Address (PPA). Missing in mapping table cache causes extra read transactions to flash storage which results in stalls of I/O requests processing in SSDs. Random read requests are affected more than random write requests since write requests can be handled by write cache effectively. In this paper, we analyze the impact of CMT on different random read requests and present a Cached Mapping Table prefetching approach which fetches logical-to-physical page translation information in order to mitigate the stalls in processing random read requests. Our experimental results show an improvement of average request waiting time by up to 13%.