Adaptive ECC Scheme for Hybrid SSD's

In recent years, multi-level cell flash memory (MLC) has been widely adopted in solid state drives (SSD's) as the major storage medium due to its lower cost and higher density, compared with single-level cell flash memory (SLC). However, MLC has reliability concerns since it has lower endurance...

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Bibliographic Details
Published in:IEEE transactions on computers 2015-12, Vol.64 (12), p.3348-3361
Main Authors: Hsieh, Jen-Wei, Chen, Chung-Wei, Lin, Han-Yi
Format: Article
Language:English
Subjects:
adaptive ECC scheme
Adaptive systems
Bit error rate
Data storage
Decoding
Density
Endurance
Error correction codes
Failure rates
Flash memories
Flash memory (computers)
Impact analysis
Management
Multimedia communication
Quantitative analysis
Random access memory
Reliability
SLC/MLC hybrid SSD
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Summary:In recent years, multi-level cell flash memory (MLC) has been widely adopted in solid state drives (SSD's) as the major storage medium due to its lower cost and higher density, compared with single-level cell flash memory (SLC). However, MLC has reliability concerns since it has lower endurance and higher disturb failure rate. Researchers thus proposed SLC/MLC hybrid SSD to exploit the advantages of SLC and MLC by separating frequently updated data in SLC and seldom modified data in MLC. In this paper, we propose an adaptive error correction code (ECC) scheme with four ECC levels to enhance the reliability of SSD's. Different from past researches, SLC is dedicated for the management of ECC, not for the user data. Since ECC is maintained in the data area of SLC (2 KB), rather than the spare area of MLC (128 Bytes), ECC capability is no longer confined by the limited size of the spare area. With adaptive management, ECC capability for a page would be upgraded whenever the current 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 scheme.
ISSN:0018-9340
1557-9956
DOI:10.1109/TC.2015.2401028