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LCTES 2018
co-located with PLDI 2018

Flash-based SSD RAID arrays are increasingly being deployed in data centers. Compared with HDD arrays, SSD arrays drastically enhance storage density and I/O performance, and reduce power and rack space. Nevertheless, SSDs suffer aging issues. Though prior studies have been conducted to address this disadvantage, effective techniques of RAID/SSD controllers are urgently needed to extend the lifetime of SSD arrays.

In this paper, we for the first time apply approximate storage via the interplay of RAID and SSD controllers to optimize the lifespan of SSD arrays. Our basic idea is to reuse faulty blocks (those contain pages with uncorrectable errors) to store approximate data (which can tolerate more errors). By relaxing the integrity of flash blocks, we observed that the endurance of NAND flash memory can be significantly boosted, thereby providing huge potentials to significantly extend the lifetime of SSDs. Based on this observation, we propose the use of an efficient space management scheme for data allocation and FTL strategies by coordinating the interplay of RAID and SSD controllers to optimize the lifetime of SSD array. We implemented a prototype, called FreeRAID, based on an SSD array simulator. Our experiments show that we can significantly increase the lifetime by up to 2.17× compared with conventional SSD-based RAID array.

Tue 19 Jun

14:00 - 15:40: LCTES 2018 - Full paper session on Adaptation and Hardware at Discovery AB
LCTES-2018-papers14:00 - 14:25
Ben TaylorLancaster University, UK, Vicent Sanz MarcoLancaster University, Willy WolffLancaster University, Yehia ElkhatibLancaster University, Zheng WangLancaster University
LCTES-2018-papers14:25 - 14:50
Lei Han, Zhaoyan ShenThe Hong Kong Polytechnic University, Zili ShaoThe Hong Kong Polytechnic University, Tao LiUniversity of Florida
LCTES-2018-papers14:50 - 15:15
Bernhard EggerSeoul National University, Eunjin SongSeoul National University, Hochan LeeSeoul National University, Daeyoung ShinSeoul National University
LCTES-2018-papers15:15 - 15:40
Michael StokesFlorida State University, Ryan BairdFlorida State University, Zhaoxiang JinMichigan Technological University, David B. Whalley, Soner OnderMichigan Technological University