WARM: Improving NAND flash memory lifetime with write-hotness aware retention management

Yixin Luo, Yu Cai, Saugata Ghose, Jongmoo Choi, Onur Mutlu

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

Abstract

Increased NAND flash memory density has come at the cost of lifetime reductions. Flash lifetime can be extended by relaxing internal data retention time, the duration for which a flash cell correctly holds data. Such relaxation cannot be exposed externally to avoid altering the expected data integrity property of a flash device. Reliability mechanisms, most prominently refresh, restore the duration of data integrity, but greatly reduce the lifetime improvements from retention time relaxation by performing a large number of write operations. We find that retention time relaxation can be achieved more efficiently by exploiting heterogeneity in write-hotness, i.e., the frequency at which each page is written. We propose WARM, a write-hotness aware retention management policy for flash memory, which identifies and physically groups together write-hot data within the flash device, allowing the flash controller to selectively perform retention time relaxation with little cost. When applied alone, WARM improves overall flash lifetime by an average of 3.24× over a conventional management policy without refresh, across a variety of real I/O workload traces. When WARM is applied together with an adaptive refresh mechanism, the average lifetime improves by 12.9×, 1.21× over adaptive refresh alone.

Original languageEnglish (US)
Title of host publication31st Symposium on Massive Storage Systems and Technologies, MSST 2015
PublisherIEEE Computer Society
ISBN (Electronic)9781467376198
DOIs
StatePublished - Aug 17 2015
Externally publishedYes
Event31st Symposium on Massive Storage Systems and Technologies, MSST 2015 - Santa Clara, United States
Duration: May 30 2015Jun 5 2015

Publication series

NameIEEE Symposium on Mass Storage Systems and Technologies
Volume2015-August
ISSN (Print)2160-1968

Conference

Conference31st Symposium on Massive Storage Systems and Technologies, MSST 2015
CountryUnited States
CitySanta Clara
Period5/30/156/5/15

Keywords

  • Ash
  • Error correction codes
  • Memory management
  • Performance evaluation
  • Reliability
  • Resource management
  • Time-frequency analysis

ASJC Scopus subject areas

  • Hardware and Architecture
  • Electrical and Electronic Engineering

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