ZombieNAND: Resurrecting dead NAND flash for improved SSD longevity

Ellis H. Wilson, Myoungsoo Jung, Mahmut T. Kandemir

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)

Abstract

As consumer pressure for more bits per dollar and higher density-per-solid-state disk (SSD) forces manufacturers to squeeze more than one bit per flash cell and feature sizes downwards, wear-out is again becoming an increasing concern. Specifically, while single-level cell flash at larger feature sizes used to boast over 100,000 program/erase (P/E) cycles, modern triple-level cell flash can only sustain a measly 3,000 P/E cycles before it can no longer be reliably used. However, one lesser known facet of NAND flash design is that there is no material difference between cells that store one, two, or three bits per cell - it is merely a logical interpretation of the cells contents. Therefore, in this work we leverage this interesting property to explore how resurrecting dead flash cells to create 'Zombie-NAND' flash can improve an SSD's lifetime, and what, if any, impact on latency results in doing such. Specifically, we analyze the impact of switching a TLC or MLC cell down one bit upon death, this allows the voltage thresholds to rise and life, though at a lower capacity, to continue for that cell. Finding that traditional wear-leveling techniques actually inhibit the benefits of this scheme, we propose and explore how controlled 'wear-unleveling' can work in tandem with Zombie-NAND cells to provide vastly increased life and decreased latencies for the drive. In this exploration, we perform rigorous performance measurement over a number of parameters representative of a variety of commodity and commercial SSDs.

Original languageEnglish
Title of host publicationProceedings - 2014 22nd Annual IEEE International Symposium on Modeling, Analysis and Simulation of Computer, and Telecommunication Systems, MASCOTS 2014
PublisherIEEE Computer Society
Pages229-238
Number of pages10
EditionFebruary
ISBN (Electronic)9781479956104
DOIs
Publication statusPublished - 2015 Feb 5
Event2014 22nd Annual IEEE International Symposium on Modeling, Analysis and Simulation of Computer, and Telecommunication Systems, MASCOTS 2014 - Paris, France
Duration: 2014 Sep 92014 Sep 11

Publication series

NameProceedings - IEEE Computer Society's Annual International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunications Systems, MASCOTS
NumberFebruary
Volume2015-February
ISSN (Print)1526-7539

Conference

Conference2014 22nd Annual IEEE International Symposium on Modeling, Analysis and Simulation of Computer, and Telecommunication Systems, MASCOTS 2014
CountryFrance
CityParis
Period14/9/914/9/11

Fingerprint

NAND
Flash
Cell
Wear of materials
Threshold voltage
Latency
Cycle
Performance Measurement
Facet
Leverage
Lifetime
Continue
Voltage

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering
  • Computer Networks and Communications
  • Software
  • Modelling and Simulation

Cite this

Wilson, E. H., Jung, M., & Kandemir, M. T. (2015). ZombieNAND: Resurrecting dead NAND flash for improved SSD longevity. In Proceedings - 2014 22nd Annual IEEE International Symposium on Modeling, Analysis and Simulation of Computer, and Telecommunication Systems, MASCOTS 2014 (February ed., pp. 229-238). [7033659] (Proceedings - IEEE Computer Society's Annual International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunications Systems, MASCOTS; Vol. 2015-February, No. February). IEEE Computer Society. https://doi.org/10.1109/MASCOTS.2014.37
Wilson, Ellis H. ; Jung, Myoungsoo ; Kandemir, Mahmut T. / ZombieNAND : Resurrecting dead NAND flash for improved SSD longevity. Proceedings - 2014 22nd Annual IEEE International Symposium on Modeling, Analysis and Simulation of Computer, and Telecommunication Systems, MASCOTS 2014. February. ed. IEEE Computer Society, 2015. pp. 229-238 (Proceedings - IEEE Computer Society's Annual International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunications Systems, MASCOTS; February).
@inproceedings{c8d709533ecf4161b4b1d9ad3655fba3,
title = "ZombieNAND: Resurrecting dead NAND flash for improved SSD longevity",
abstract = "As consumer pressure for more bits per dollar and higher density-per-solid-state disk (SSD) forces manufacturers to squeeze more than one bit per flash cell and feature sizes downwards, wear-out is again becoming an increasing concern. Specifically, while single-level cell flash at larger feature sizes used to boast over 100,000 program/erase (P/E) cycles, modern triple-level cell flash can only sustain a measly 3,000 P/E cycles before it can no longer be reliably used. However, one lesser known facet of NAND flash design is that there is no material difference between cells that store one, two, or three bits per cell - it is merely a logical interpretation of the cells contents. Therefore, in this work we leverage this interesting property to explore how resurrecting dead flash cells to create 'Zombie-NAND' flash can improve an SSD's lifetime, and what, if any, impact on latency results in doing such. Specifically, we analyze the impact of switching a TLC or MLC cell down one bit upon death, this allows the voltage thresholds to rise and life, though at a lower capacity, to continue for that cell. Finding that traditional wear-leveling techniques actually inhibit the benefits of this scheme, we propose and explore how controlled 'wear-unleveling' can work in tandem with Zombie-NAND cells to provide vastly increased life and decreased latencies for the drive. In this exploration, we perform rigorous performance measurement over a number of parameters representative of a variety of commodity and commercial SSDs.",
author = "Wilson, {Ellis H.} and Myoungsoo Jung and Kandemir, {Mahmut T.}",
year = "2015",
month = "2",
day = "5",
doi = "10.1109/MASCOTS.2014.37",
language = "English",
series = "Proceedings - IEEE Computer Society's Annual International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunications Systems, MASCOTS",
publisher = "IEEE Computer Society",
number = "February",
pages = "229--238",
booktitle = "Proceedings - 2014 22nd Annual IEEE International Symposium on Modeling, Analysis and Simulation of Computer, and Telecommunication Systems, MASCOTS 2014",
address = "United States",
edition = "February",

}

Wilson, EH, Jung, M & Kandemir, MT 2015, ZombieNAND: Resurrecting dead NAND flash for improved SSD longevity. in Proceedings - 2014 22nd Annual IEEE International Symposium on Modeling, Analysis and Simulation of Computer, and Telecommunication Systems, MASCOTS 2014. February edn, 7033659, Proceedings - IEEE Computer Society's Annual International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunications Systems, MASCOTS, no. February, vol. 2015-February, IEEE Computer Society, pp. 229-238, 2014 22nd Annual IEEE International Symposium on Modeling, Analysis and Simulation of Computer, and Telecommunication Systems, MASCOTS 2014, Paris, France, 14/9/9. https://doi.org/10.1109/MASCOTS.2014.37

ZombieNAND : Resurrecting dead NAND flash for improved SSD longevity. / Wilson, Ellis H.; Jung, Myoungsoo; Kandemir, Mahmut T.

Proceedings - 2014 22nd Annual IEEE International Symposium on Modeling, Analysis and Simulation of Computer, and Telecommunication Systems, MASCOTS 2014. February. ed. IEEE Computer Society, 2015. p. 229-238 7033659 (Proceedings - IEEE Computer Society's Annual International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunications Systems, MASCOTS; Vol. 2015-February, No. February).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

TY - GEN

T1 - ZombieNAND

T2 - Resurrecting dead NAND flash for improved SSD longevity

AU - Wilson, Ellis H.

AU - Jung, Myoungsoo

AU - Kandemir, Mahmut T.

PY - 2015/2/5

Y1 - 2015/2/5

N2 - As consumer pressure for more bits per dollar and higher density-per-solid-state disk (SSD) forces manufacturers to squeeze more than one bit per flash cell and feature sizes downwards, wear-out is again becoming an increasing concern. Specifically, while single-level cell flash at larger feature sizes used to boast over 100,000 program/erase (P/E) cycles, modern triple-level cell flash can only sustain a measly 3,000 P/E cycles before it can no longer be reliably used. However, one lesser known facet of NAND flash design is that there is no material difference between cells that store one, two, or three bits per cell - it is merely a logical interpretation of the cells contents. Therefore, in this work we leverage this interesting property to explore how resurrecting dead flash cells to create 'Zombie-NAND' flash can improve an SSD's lifetime, and what, if any, impact on latency results in doing such. Specifically, we analyze the impact of switching a TLC or MLC cell down one bit upon death, this allows the voltage thresholds to rise and life, though at a lower capacity, to continue for that cell. Finding that traditional wear-leveling techniques actually inhibit the benefits of this scheme, we propose and explore how controlled 'wear-unleveling' can work in tandem with Zombie-NAND cells to provide vastly increased life and decreased latencies for the drive. In this exploration, we perform rigorous performance measurement over a number of parameters representative of a variety of commodity and commercial SSDs.

AB - As consumer pressure for more bits per dollar and higher density-per-solid-state disk (SSD) forces manufacturers to squeeze more than one bit per flash cell and feature sizes downwards, wear-out is again becoming an increasing concern. Specifically, while single-level cell flash at larger feature sizes used to boast over 100,000 program/erase (P/E) cycles, modern triple-level cell flash can only sustain a measly 3,000 P/E cycles before it can no longer be reliably used. However, one lesser known facet of NAND flash design is that there is no material difference between cells that store one, two, or three bits per cell - it is merely a logical interpretation of the cells contents. Therefore, in this work we leverage this interesting property to explore how resurrecting dead flash cells to create 'Zombie-NAND' flash can improve an SSD's lifetime, and what, if any, impact on latency results in doing such. Specifically, we analyze the impact of switching a TLC or MLC cell down one bit upon death, this allows the voltage thresholds to rise and life, though at a lower capacity, to continue for that cell. Finding that traditional wear-leveling techniques actually inhibit the benefits of this scheme, we propose and explore how controlled 'wear-unleveling' can work in tandem with Zombie-NAND cells to provide vastly increased life and decreased latencies for the drive. In this exploration, we perform rigorous performance measurement over a number of parameters representative of a variety of commodity and commercial SSDs.

UR - http://www.scopus.com/inward/record.url?scp=84937894022&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84937894022&partnerID=8YFLogxK

U2 - 10.1109/MASCOTS.2014.37

DO - 10.1109/MASCOTS.2014.37

M3 - Conference contribution

AN - SCOPUS:84937894022

T3 - Proceedings - IEEE Computer Society's Annual International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunications Systems, MASCOTS

SP - 229

EP - 238

BT - Proceedings - 2014 22nd Annual IEEE International Symposium on Modeling, Analysis and Simulation of Computer, and Telecommunication Systems, MASCOTS 2014

PB - IEEE Computer Society

ER -

Wilson EH, Jung M, Kandemir MT. ZombieNAND: Resurrecting dead NAND flash for improved SSD longevity. In Proceedings - 2014 22nd Annual IEEE International Symposium on Modeling, Analysis and Simulation of Computer, and Telecommunication Systems, MASCOTS 2014. February ed. IEEE Computer Society. 2015. p. 229-238. 7033659. (Proceedings - IEEE Computer Society's Annual International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunications Systems, MASCOTS; February). https://doi.org/10.1109/MASCOTS.2014.37