CAFTL: a content-aware flash translation layer enhancing the lifespan of flash memory based solid state drives

Although Flash Memory based Solid State Drive (SSD) exhibits high performance and low power consumption, a critical concern is its limited lifespan along with the associated reliability issues. In this paper, we propose to build a Content-Aware Flash Translation Layer (CAFTL) to enhance the endurance of SSDs at the device level. With no need of any semantic information from the host, CAFTL can effectively reduce write traffic to flash memory by removing unnecessary duplicate writes and can also substantially extend available free flash memory space by coalescing redundant data in SSDs, which further improves the efficiency of garbage collection and wear-leveling. In order to retain high data access performance, we have also designed a set of acceleration techniques to reduce the runtime overhead and minimize the performance impact caused by extra computational cost. Our experimental results show that our solution can effectively identify up to 86.2% of the duplicate writes, which translates to a write traffic reduction of up to 24.2% and extends the flash space by a factor of up to 31.2%. Meanwhile, CAFTL only incurs a minimized performance overhead by a factor of up to 0.5%.