SAC: A Stream Aware Write Cache Scheme for Multi-Streamed Solid State Drives

Abstract

This work found that the state-of-the-art multi-streamed SSDs are inefficiently used due to two issues. First, the write cache inside SSDs is not aware of data from different streams, which induce conflict among streams. Second, the current stream identification methods are not accurate, which should be optimized inside SSDs. This work proposed a novel write cache scheme to efficiently utilize and optimize the multiple streams. First, an inter-stream aware cache partitioning scheme is proposed to manage the data from different streams. Second, an intra-stream based active cache evicting scheme is proposed to evict data to block with more invalid pages in priority. Experiment results show that the proposed scheme significantly reduces the write amplification (WAF) of multi-streamed SSDs by up to 28% with negligible cost.