On efficient wear leveling for large-scale flash-memory storage systems
Proceedings of the 2007 ACM symposium on Applied computing
A log buffer-based flash translation layer using fully-associative sector translation
ACM Transactions on Embedded Computing Systems (TECS)
Proceedings of the 14th international conference on Architectural support for programming languages and operating systems
Characterizing flash memory: anomalies, observations, and applications
Proceedings of the 42nd Annual IEEE/ACM International Symposium on Microarchitecture
Write endurance in flash drives: measurements and analysis
FAST'10 Proceedings of the 8th USENIX conference on File and storage technologies
Rejuvenator: A static wear leveling algorithm for NAND flash memory with minimized overhead
MSST '11 Proceedings of the 2011 IEEE 27th Symposium on Mass Storage Systems and Technologies
Error patterns in MLC NAND flash memory: measurement, characterization, and analysis
DATE '12 Proceedings of the Conference on Design, Automation and Test in Europe
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NAND flash-based solid state drives (SSDs) are replacing magnetic disks because of their fast random access performance, shock resistance, and low power consumption. However, the number of program and erase cycles that can be performed on NAND flash is limited. To overcome this limitation, SSDs require a sophisticated wear-leveling algorithm which distributes program/erase cycles evenly across all flash blocks. While most of existing wear-leveling algorithms are only based on the erase counts of flash blocks, our empirical study indicates that the erase count alone is not a good wear index which tells us how much a flash block is worn out. This paper proposes a new wear index for MLC NAND flash memory which takes into account more diverse properties of NAND flash memory. To show the effectiveness of the proposed wear index, we also develop a wear-leveling algorithm, named Equalizer. In our evaluation with three realistic workloads, Equalizer based on the proposed wear index improves the effective lifetime of SSDs by up to 145% compared to the existing wear-leveling technique based on the erase count.