Locality-Driven Dynamic Flash Cache Allocation

Flash-based SSDs are widely deployed as the storage caches to boost the system performance. However, unlike the traditional cache devices such as SRAM and DRAM, SSDs have internal garbage collection activities, which can severely degrade the cache performance. Moreover, SSD can only sustain limited P/E cycles. Therefore, traditional cache hit ratio oriented optimizations might not obtain the optimal performance for the SSD cache and can even shorten the device lifetime, especially for the SSD write cache, which could introduce more internal garbage collection processes and lifetime concerns. In this paper, we propose a reuse distance aware cache management to improve both the performance and lifetime of SSD-based write cache by compromising the cache hit ratio and the internal garbage collection overhead.