Zone-based shortest positioning time first scheduling for MEMS-based storage devices

Abstract

Access latency to secondary storage devices is frequently a limiting factor in computer system performance. New storage technologies promise to provide greater storage densities at lower latencies than is currently obtainable with hard disk drives. MEMS-based storage devices use orthogonal magnetic or physical recording techniques and thousands of simultaneously active MEMS-based read-write tips to provide high-density low-latency nonvolatile storage. These devices promise seek times 10-20 times faster than hard drives, storage densities 10 times greater, and power consumption an order of magnitude lower. Previous research has examined data layout and request ordering algorithms that are analogs of those developed for hard drives. We present an analytical model of MEMS device performance that motivates a computationally simple MEMS-based request scheduling algorithm called ZSPTF, which has average response times comparable to shortest positioning time first (SPTF) but with response time variability comparable to circular scan (C-SCAN).