Research pick: Solid state life extension - "Extending the lifetime of NAND flash-based SSD through compacted write"

Solid-state storage on mobile devices and computers is becoming de rigeur, it offers much shorter read and write times for data than conventional magnetic storage devices with spinning disks and other moving parts, it uses far less power, and it is silent in operation. But, those advantages come at a cost in that all the rapid reading and writing of data can wear out the device much faster than a conventional hard disk. There are techniques for reducing the wear based in software and settings, but ultimately lifespan is rather limited and there is an urgent need to developed solid-state storage that has greater longevity.

Research published in the International Journal of Embedded Systems offers a new approach to reducing the number of read-writes that occur when data is stored on one particular type of solid-state media, the solid-state disk (SSD). These are commonly used to replace magnetic hard disks in personal computers and laptops offering faster bootup and quicker access to data files.

Hai-Tao Wu and Tian-Ming Yang of Huanghuai University in Henan, China, Ping Huang of Temple University, Philadelphia, USA, and Wen-Kuang Chou of Providence University, Taichung, Taiwan, explain that the problem of SSD electronic wear and tear is due to the legacy of traditional file systems on mechanical drives which involvs a lot of partial page rights.

The team has traced the write activity in an SSD and found that partial page writes are most common for the heads and tails of large write requests. This, the team suggests, means that it might be possible to reduce the number of writes made by compressing two partial page writes from the same large write request into a single page before the data are written into flash. This would reduce significantly the number of accesses to each bit of memory and so prolong the lifespan of the device.

The team adds that their novel approach to prolonging the life of an SSD not only reduces erase number but write latency, and read latency by up to 69%, 47%, and 50%, respectively.

Wu, H-T., Yang, T-M., Huang, P. and Chou, W-K. (2020) ‘Extending the lifetime of NAND flash-based SSD through compacted write’, Int. J. Embedded Systems, Vol. 13, No. 2, pp.129–135.