Improving SSD reliability with RAID via Elastic Striping and Anywhere Parity

Jaeho Kim, Jongmin Lee, Jongmoo Choi, Donghee Lee, Sam H. Noh

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

57 Scopus citations

Abstract

While the move from SLC to MLC/TLC flash memory technology is increasing SSD capacity at lower cost, it is being done at the cost of sacrificing reliability. An approach to remedy this loss is to employ the RAID architecture with the chips that comprise SSDs. However, using the traditional RAID approach may result in negative effects as the total number of writes may increase due to the parity updates, consequently leading to increased P/E cycles and higher bit error rates. Using a technique that we call Elastic Striping and Anywhere Parity (eSAP), we develop eSAP-RAID, a RAID scheme that significantly reduces parity writes while providing reliability better than RAID-5. We derive performance and lifetime models of SSDs employing RAID-5 and eSAP-RAID that show the benefits of eSAP-RAID. We also implement these schemes in SSDs using DiskSim with SSD Extension and validate the models using realistic workloads. Our results show that eSAP-RAID improves reliability considerably, while limiting its wear. Specifically, the expected lifetime of eSAP-RAID employing SSDs may be as long as current ECC based SSDs, while its reliability level can be maintained at the level of the early stages of current ECC based SSDs throughout its entire lifetime.

Original languageEnglish
Title of host publication2013 43rd Annual IEEE/IFIP International Conference on Dependable Systems and Networks, DSN 2013
DOIs
StatePublished - 2013
Event2013 43rd Annual IEEE/IFIP International Conference on Dependable Systems and Networks, DSN 2013 - Budapest, Hungary
Duration: 24 Jun 201327 Jun 2013

Publication series

NameProceedings of the International Conference on Dependable Systems and Networks

Conference

Conference2013 43rd Annual IEEE/IFIP International Conference on Dependable Systems and Networks, DSN 2013
Country/TerritoryHungary
CityBudapest
Period24/06/1327/06/13

Keywords

  • Flash memory
  • RAID
  • Reliability
  • SSD

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