University of Hertfordshire

By the same authors

A Case for Redundant Arrays of Hybrid Disks (RAHD)

Research output: Contribution to journalArticle


  • F. Wang
  • N. Helian
  • S. Wu
  • Y.K. Guo
  • D. Deng
  • V. Khare
  • C. Liao
  • M. Rashidi
  • A. Parker
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Original languageEnglish
Pages (from-to)3738-3741
JournalIEEE Transactions on Magnetics
Journal publication date2008
Publication statusPublished - 2008


Hybrid Hard Disk Drive was originally concepted by Samsung, which incorporates a Flash memory in a magnetic disk. The combined ultra-high-density benefits of magnetic storage and the low-power and fast read access of NAND technology inspires us to construct Redundant Arrays of Hybrid Disks (RAHD) to offer a possible alternative to today’s Redundant Arrays of Independent Disks (RAIDs)
and/or Massive Arrays of Idle Disks (MAIDs). We first design an internal management system (including Energy-Efficient Control) for hybrid disks. Three traces collected from real systems as well as a synthetic trace are then used to evaluate the RAHD arrays. The trace-driven experimental results show: in the high speed mode, a RAHD outplays the purely-magnetic-disk-based RAIDs by a factor of 2.4–4; in the energy-efficient mode, a RAHD4/5 can save up to 89% of energy at little performance degradation

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