CLOCK-DNV: A write buffer algorithm for flash storage devices of consumer electronics

Today, flash storage devices have become a standard storage in consumer electronics devices, such as smartphones, smart tablets, and smart TVs, due to their attractive features. Since flash storage helps to cut down on system response for customers, consumer devices based on the flash storage are gradually increasing. Unfortunately, the flash storage of consumer electronics devices suffers from random write requests because applications running on the consumer device simultaneously issue a lot of write operations to store their persistent data. This paper proposes a novel write buffer algorithm, called Clock with DRAM and NVM hybrid write buffer (CLOCK-DNV), that reshapes random write requests into sequential ones. In order to maximize the number of consecutive write requests, CLOCK-DNV takes the benefits of NVM media with the dirty page padding mechanism. For extensive evaluation, the proposed algorithm is implemented on a flash storage simulator, which is widely used for performance analysis, and is compared with two write buffer algorithms, FAB and CBM. The evaluation results clearly show that CLOCK-DNV maintains higher hit ratios than other write buffer algorithms. Moreover, CLOCK-DNV efficiently reduces the number of write requests issued to the underlying flash memory by up to 56% compared with the state-of-the-art algorithm, CBM, while extending the endurance of flash storage by up to 56%.