KV-FTL: A novel key-value based FTL scheme for large scale SSDs

摘要

Both traditional coarse-grained and fine-grained Flash Translation Layer schemes are unsuitable for ultra-large SSDs. They produce overmuch mapping entries which fail to be kept in embedded DRAM completely and can suffer severely from low spatial and temporal localities. In this paper, we propose a novel KV-FTL for ultra-large SSDs, which mostly maps logical addresses to physical addresses via a simple hash function, while handles hash collisions and out-of-place data updates by the traditional manner, i.e., the mapping table. Our KV-FTL can accelerate address translation by avoiding loading mapping table from flash memory to DRAM, thus improve performance; as well as reduce the write-traffic incurred by the mapping table, thus extend the lifespan of SSDs. Experimental results show that our KV-FTL facilitates SSDs to survive longer lifespan by a factor of up to 18.7% with an average of 13.6%; improves read performance ranging from 18.4% to 50.7% with an average of 39% with optimization, and in the case of extremely intensive requests, improves the access performance for requests with an average of 47%.