University of Leicester
Browse
M-and-M-McEwan-Komsul-2016.pdf (2.7 MB)

Age Aware Pre-emptive Garbage Collection for SSD RAID

Download (2.7 MB)
journal contribution
posted on 2018-03-28, 14:01 authored by Alistair A. McEwan, Muhammed Z. Komsul
Flash-based storage systems offer high performance, robustness, and reliability for embedded applications; however the physical nature of flash memory means that there are limitations to its usage in high reliability applications. In previous work, we have developed RAID architectures and associated controller hardware that increase the reliability and lifespan of these storage systems. However, flash memory needs regular garbage collection and this presents two issues in a high reliability context. The first issue concerns response times as when a garbage collector is active, the flash memory cannot be used by the application layer. This non-determinism in terms of response is problematic in high reliability systems that require real-time guarantees. The second issue concerns lifespan of flash chips. If the garbage collector is allowed free rein over erase operations while garbage collecting, this affects management of the lifespan of each SSD in the array. In this paper we present an enhanced, dynamic, real-time garbage collection method for SSD RAID that does not ignore the strict age distribution management, while offering deterministic response times for access. Real-time efficiency is further improved by dynamically coordinating garbage collection across each device in the array. Our simulation results indicate that the dynamic garbage collection technique maintains the age distribution at a level that does not affect reliability of individual devices. This is evidences using various synthetic and realistic traces dominated by random I/O loads.

History

Citation

Microprocessors and Microsystems, 2018, 56, pp. 13-21

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Engineering

Version

  • AM (Accepted Manuscript)

Published in

Microprocessors and Microsystems

Publisher

Elsevier

issn

0141-9331

eissn

1872-9436

Acceptance date

2017-10-23

Copyright date

2017

Available date

2018-10-26

Publisher version

https://www.sciencedirect.com/science/article/pii/S0141933116304215?via=ihub

Notes

The file associated with this record is under embargo until 12 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.

Language

en

Usage metrics

    University of Leicester Publications

    Categories

    Keywords

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC