Sequentiality-Aware Hash-based FTL

Jaemin Shin, Ilbo Jeong, Li Xiaochang, Jihong Kim

http://doi.org/10.5626/JOK.2020.47.8.717

As the capacity of an SSD significantly increases, the SSD needs a larger DRAM for managing SSD-internal information. Since the cost of DRAM is an important factor in deciding the overall SSD price, it is important to reduce the DRAM cost without a performance degradation. In this paper, we propose a novel hash-based FTL mapping technique that meets this goal. Unlike an existing hash-based scheme, our technique introduces a virtual block scheme which enables to exploit the sequentiality of the logical address which effectively reduces the garbage collection overhead. Experimental results showed that SEQhFTL can reduce this overhead as much as PFTL while only maintaining 39% of PFTL’s metadata used on average.