Lightweight data compression for mobile flash storage

Data compression is beneficial to flash storage lifespan. However, because the design of mobile flash storage is highly cost-sensitive, hardware compression becomes a less attractive option. This study investigates the feasibility of data compression on mobile flash storage. It first characterizes data compressibility based on mobile apps, and the analysis shows that write traffic bound for mobile storage volumes is highly compressible. Based on this finding, a lightweight approach is introduced for firmware-based data compression in mobile flash storage. The controller and flash module work in a pipelined fashion to hide the data compression overhead. Together with this pipelined design, the proposed approach selectively compresses incoming data of high compressibility, while leaving data of low compressibility to a compression-aware garbage collector. Experimental results show that our approach greatly reduced the frequency of block erase by 50.5% compared to uncompressed flash storage. Compared to unconditional data compression, our approach improved the write latency by 10.4% at a marginal cost of 4% more block erase operations.