On trading wear-leveling with heal-leveling

Manufacturers are constantly seeking to increase flash memory density in order to fulfill the ever growing demand for storage capacity. However, this trend significantly reduces the reliability and endurance of flash memory chips. The lifetime degradation worsens as the number of erase cycles grows, even with wear leveling technology being adopted to extend flash memory lifetime by evenly distributing erase cycles to every flash block. To address this issue, self-healing technology is proposed to recover a flash block before the flash block is worn out, but such a technology still has its limitation when recovering flash blocks. In contrast to the existing wear leveling designs, we adopt the self-healing technology to propose a heal-leveling design that evenly distributes healing cycles to flash blocks. Ultimately, heal-leveling aims to extend the lifetime of flash memory without introducing a large amount of live-data copying overheads. We conducted a series of experiments to evaluate the capability of the proposed design. The results show that our design can significantly improve the access performance and the effective lifetime of flash memory without the unnecessary overheads caused by wear leveling technology.