PROJECT TITLE :

Adaptive ECC Scheme for Hybrid SSD’s

ABSTRACT:

In recent times, multi-level cell flash memory (MLC) has been widely adopted in solid state drives (SSD’s) as the most important storage medium due to its lower price and higher density, compared with single-level cell flash memory (SLC). However, MLC has reliability issues since it's lower endurance and better disturb failure rate. Researchers so proposed SLC/MLC hybrid SSD to exploit the advantages of SLC and MLC by separating frequently updated data in SLC and infrequently modified data in MLC. During this paper, we tend to propose an adaptive error correction code (ECC) theme with four ECC levels to enhance the reliability of SSD’s. Different from past researches, SLC is devoted for the management of ECC, not for the user information. Since ECC is maintained in the information area of SLC (a pair of KB), instead of the spare space of MLC (128 Bytes), ECC capability is not confined by the limited size of the spare area. With adaptive management, ECC capability for a page would be upgraded whenever this ECC cannot guarantee its reliability. A quantitative analysis is conducted to explore the impacts of different settings. The experiment results show that the lifetime of SSD can be extended by 318 percent for the trace of OLTP applications with our adaptive ECC theme.