A Case for Redundant Arrays of Hybrid Disks (RAHD)

Wang, F., Helian, N., Wu, S., Guo, Y.K., Deng, D., Khare, V., Liao, C., Rashidi, M. and Parker, A. (2008) A Case for Redundant Arrays of Hybrid Disks (RAHD). IEEE Transactions on Magnetics, 44 (11). pp. 3738-3741. ISSN 0018-9464

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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