Physical Modeling of Probe-Based Storage

Magnetic disks may be reaching physical performance limits due to the superparamagnetic effect. To close the performance gap between processors and storage, researchers are exploring a variety of new storage technologies [17]. Among these new technologies, probe-based micro-electrical mechanical systems (MEMS) magnetic storage arrays are attractive [3]. Probe-based storage is dense and highly parallel. It uses rectilinear motion in contrast to rotating media. Commercial devices are expected within the next several years. The wide range of possible architectures and the unique performance characteristics of probe-based storage require that standard file system algorithms for disks, including scheduling and layout, must be revisited to determine their efficiency domain. Because these devices do not yet exist, analysis of system performance depends on simulation models. At this early stage of development, models that bridge the gap between the physics of the device and its performance characteristics can provide important feedback to both hardware and software designers. This paper compares results from three models of probe-based storage that convey successively more accurate descriptions of the underlying physics. We conclude that the physical accuracy of the model has a significant impact on the predicted performance under real workloads.