Write-aware buffer management policy for performance and durability enhancement in NAND flash memory

The popularity of NAND flash memory has been growing rapidly in recent years, but the SSD (Solid-State Disk) has shown limited success in its battle against the hard disk. Besides the high price, SSD suffers performance degradation under random write requests, due to the intrinsic weak points of NAND flash: erase-before-write, asymmetric read/write access time, and limited program/erase cycles. In order to overcome these drawbacks, many buffer replacement algorithms have been proposed. However, considering the cost of write operations, it would be beneficial to have dirty pages updated before being flushed to flash memory. In this paper, we propose a new buffer management scheme to retain write-intensive pages in the buffer, and we confirm its effectiveness by applying it to one of the existing buffer management schemes. The simulation results indicate that the proposed scheme reduces up to 30% of the write count, and, therefore, extends the lifetime of NAND flash memories.