LFSS: Using an extra RAM buffer for improving flash storage system performance

Erasing flash memory blocks is a time-consuming and energy-wasting operation. Moreover, the number of erase times is also limited. In this paper, we propose using ah extra RAM buffer as the extension of the flash memory to reduce the number of erase operations, and to prolong the flash lifetime. Based on the extra RAM buffer, we design and implement a flash storage system, called Log Flash Storage System (LFSS), which incorporates two techniques. One is a novel data clustering method, which allows the hot data usually be updated in the RAM buffer, reducing the chances of updating and erasing flash blocks. The other is a new data layout approach for the flash memory so as to reduce the system mount time. We implemented the LFSS as a Linux kernel module. According to the performance results, LFSS can eliminate 40%-90% of the erase operations when a 4Mbyte RAM buffer is used. In addition, it can also ensure even wearing.