Variation of SCM/NAND Flash Hybrid SSD Performance, Reliability and Cost by Using Different SSD Configurations and Error Correction Strengths

Hirofumi TAKISHITA  Shuhei TANAKAMARU  Sheyang NING  Ken TAKEUCHI  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E99-C   No.4   pp.444-451
Publication Date: 2016/04/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E99.C.444
Type of Manuscript: Special Section PAPER (Special Section on Solid-State Circuit Design---Architecture, Circuit, Device and Design Methodology)
Category: 
Keyword: 
solid-state drive,  storage-class memory,  NAND flash memory,  error correcting code,  

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Summary: 
Storage-Class Memory (SCM) and NAND flash hybrid Solid-State Drive (SSD) has advantages of high performance and low power consumption compared with NAND flash only SSD. In this paper, first, three SSD configurations are investigated. Three different SCMs are used with 0.1 µs, 1 µs and 10 µs read/write latencies, respectively, and the required SCM/NAND flash capacity ratios are analyzed to maintain the same SSD performance. Next, by using the three SSD configurations, the variation of SSD reliability, performance and cost are analyzed by changing error correction strengths. The SSD reliability of acceptable SCM and NAND flash Bit Error Rates (BERs) is limited by achieving specified SSD performance with error correction, and/or limited by SCM and NAND flash parity size and SSD cost. Lastly, the SSD replacement cost is also analyzed by considering the limitation of NAND flash write/erase cycles. The purpose of this paper is to provide a design guideline for obtaining high performance, highly reliable and cost-effective SCM/NAND hybrid structure SSD with ECC.