Improving the Performance of On-Board Cache for Flash-Based Solid-State Drives

Flash-based Solid-State Drives (SSDs) are data storage devices that use flash memory to store persistent data. Previously we presented a centralized on-board cache for SSDs to improve the response time and reduce the physical writes to the flash media. An automatic periodic update (APU) feature with fixed period is used to write dirty and stable cache lines to flash media when the SSD is idle. In this work we propose a distributed on-board cache architecture to match the intrinsic parallelism of SSDs. Since there are N individual flash packages in one SSD device, N dirty cache lines are selected by the APU feature, each of which is written to a separate flash package. Simulation results show that this distributed on-board cache can significantly reduce the response time of SSDs by up to 90% compared with the SSDs without such a cache, while reducing the number of physical writes to the flash memory.