Modeling and performance of MEMS-based storage devices

Abstract

MEMS-based storage devices are seen by many as promising alternatives to disk drives. Fabricated using conventional CMOS processes, MEMS-based storage consists of thousands of small, mechanical probe tips that access gigabytes of high-density, nonvolatile magnetic storage. This paper takes a first step towards understanding the performance characteristics of these devices by mapping them onto a disk-like metaphor. Using simulation models based on the mechanics equations governing the devices' operation, this work explores how different physical characteristics ( e.g. , actuator forces and per-tip data rates) impact the design trade-offs and performance of MEMS-based storage. Overall results indicate that average access times for MEMS-based storage are 6.5 times faster than for a modern disk (1.5 ms vs. 9.7 ms). Results from filesystem and database bench-marks show that this improvement reduces application I/O stall times up to 70%, resulting in overall performance improvements of 3X.

Design of servo control systems with quadratic optimal control and observed-state feedback control for mems-based storage device

“…A new storage technology, based on MEMS, is an exciting new technology that could provide significant I/O performance over current disk drive technology and at costs much lower than EEPROM technology (Brown 1998;Carley et al 2000a). Based on MEMS, this non-volatile storage technology merges magnetic recording material and thousands of recording heads to provide storage capacity of 1-10 GB of data in the size of a penny with access times 10-20 times faster than hard drives and streaming bandwidths of over 50 MB/s (Schlosser et al 1999Griffin et al 2000a).…”

“…As disk drives, MEMS-based storage device has recording heads called probe tips and a recording media surface that moves (Scholosser et al 1999;Griffin et al 2000a). MEMS probe tips are fabricated in a parallel wafer-level manufacturing process.…”

“…An entire media sled holds thousands of tip regions. Each rectangular area stores M · N bits, organized into vertical columns called tip sectors that contain encoded data bits and servo information that identify the sector and track information (Griffin et al 2000a;Scholosser et al 2000). To read or write data, the media passes under the active tips in both the ± y directions while the tips access the data but data must be read in the direction it was written (Madhyastha and Yang 2001).…”

“…This movement is known as seek time (Griffin et al 2000a). The sled then moves at constant velocity in the y direction only, called access velocity, streaming data to or from the media.…”

“…Large transfers may require that data from multiple tracks and/or cylinders be accessed. To switch tracks during large transfers, the sled performs a turnaround (reversing direction) and may switch the set of active tips (Schlosser et al 1999;Griffin et al 2000a;Tredennick 2001).…”