Proposed Middleware Technology Quadruples SSD Write Speeds

Solid-State Drives (SSDs) are pretty quick and very reliable, but enthusiasts are always looking to get the latest and greatest drive. It turns out that there might be a way to greatly improve performance of NAND Flash devices with some software tweaks. According to Jyunichi Oshita from Tech-On, the team, headed by professor Ken Takeuchi of Chuo University, presented its findings last week at the International Memory Workshop in Taipei. Their research is covered in a paper entitled NAND Flash Aware Data Management System for High-Speed SSDs by Garbage Collection Overhead Suppression. According to Oshita, the performance gains are around 300% when it comes to write speeds and it brings down the power usage down by 60% and increases the lifespan of the NAND Flash. These results are all based on simulations for now, but you never know!

With NAND flash memory, it is not possible to overwrite data on the same memory area, making it necessary to write data on a different area and, then, invalidate the old area. As a result, data is fragmented, increasing invalid area and decreasing storage capacity. Therefore, NAND flash memories carry out “garbage collection,” which rearranges fragmented data in a continuous way and erases blocks of invalid area. This process takes 100ms or longer, drastically decreasing the writing speed of SSD.

In September 2013, to address this issue, the research team developed a method to prevent data fragmentation by making improvements to middleware that controls a storage for database applications. It makes (1) the “SE (storage engine)” middleware, which assigns logical addresses when an application software accesses a storage device, and (2) the FTL (flash translation layer) middleware, which converts logical addresses into physical addresses on the side of the SSD controller, work in conjunction. This time, the team developed a more versatile method that can be used for a wider variety of applications.

The new method forms a middleware layer called “LBA (logical block address) scrambler” between the file system (OS) and FTL. The LBA scrambler works in conjunction with the FTL and converts the logical addresses of data being written to reduce the effect of fragmentation.

In a simulation, the research team confirmed that the new technology improves the writing speed of SSD by up to 300% and reduces power consumption by up to 60% and the number of write/erase cycles by up to 55%, increasing product life. Because, with the new method, it is not necessary to make any changes to NAND flash memory, and the method is completed within the middleware, it can be applied to existing SSDs as it is.