A Case for Redundant Arrays of Hybrid Disks (RAHD)

F. Wang, N. Helian, S. Wu, Y.K. Guo, D. Deng, V. Khare, C. Liao, M. Rashidi, A. Parker

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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
Original languageEnglish
Pages (from-to)3738-3741
JournalIEEE Transactions on Magnetics
Issue number11
Publication statusPublished - 2008


  • flash memory


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