MEMS-based storage devices : integration in energy-constrained mobile systems


Khatib, Mohammed Ghiath (2009) MEMS-based storage devices : integration in energy-constrained mobile systems. thesis.

open access
Abstract:The digital era in which we are living today requires our increasing awareness
of energy efficiency to reduce the negative effects on our lovely environment.
We, people, are increasingly dealing with digital contents to facilitate
our deals, which increases the demand for larger storage capacities than ever
The environmental considerations and the data explosion worldwide are
calling for green and ultrahigh-density storage technologies. A storage technology,
based onMicro-Electro-Mechanical Systems (MEMS), promises to deliver
green and high-capacity storage systems. Storage densities up to 4 Tb/in2
have already been demonstrated. With such a technology, a storage device
with a capacity of 1 Tb can be mounted in a package smaller than a thumbnail,
dissipating oneWatt of power.
Disruptive technologies take, however, a significant amount of time to materialize
into commercial products. One key reason for this delay is the difficulty
of integrating and adopting new technologies. Integration, in a broad
sense, involves the investigation of roles a new technology can play, and solutions
to its impediments. Early solutions to the integration problem help
to reduce the time to market, and most likely contribute to the success of the
Flash memory, for instance, was invented in the eighties. The large demand
for Flash in mobile systems has drawn the attention of researchers to
investigate Flash. Just recently, researchers started looking into ways to construct
storage systems based on Flash that are reliable, have low latency, and
consume little energy. Flash memory has not found its way to enterprise storage
yet, whereas their kin, hard disk drives, are sitting there wasting a significant
amount of energy. That kind of late response to Flash is costing data
centers millions of dollars every day in energy and cooling cost.
We would like to avoid such a late response for MEMS-based storage devices
by being proactive in how we can get this family of devices successfully
integrated as early as possible. Like any other technology, MEMS-based storage
demands optimization, and has challenges that need to be tackled. In this
work, we optimize MEMS-based storage, tailor it to mobile battery-powered
systems, and compare it to Flash memory and Hybrid (Disk–Flash) storage.
The research of this dissertation looks mainly into the energy and cost aspects
of MEMS-based storage with the following two contributions. We devise
policies to reduce the energy consumption of MEMS-based storage devices.
We also propose to exploit knowledge of the expected workload in configuring
the data layout of a MEMS-based storage device in order to increase the effective
capacity. Both contributions target at satisfying the increasing demand for
green and inexpensive storage devices.
In addition to the energy and cost aspects, we make sure that the response
time and the lifetime of MEMS-based storage devices are competitive. The
data-layout and energy-saving policies account for the timing performance by
looking at configurations that do not compromise on the response time. With
respect to lifetime, we devise probe wear-leveling policies that increase the
lifetime ofMEMS-based storage devices with minimal influence on the energy
consumption and the response time.
The dissertation incorporates the conclusions from the study of the policies,
and investigates the employment of MEMS-based storage devices in important
types of mobile application. For predominately streaming applications,
we also investigate the influence of buffering on the energy consumption,
response time, and capacity of MEMS-based storage devices. We put
the technology into perspective by comparing it to Flash memory and Hybrid
(Disk–Flash) storage.
Our system-level research in this dissertation identifies potential points of
enhancement of MEMS-based storage devices. Enhancements are targeted
at reducing the energy consumption, decreasing the response time, cutting
down the per-bit cost, and increasing the lifetime of the device. Most importantly,
we show that the per-bit cost of MEMS-based storage is crucial to its
success. Our system-level contributes to reduce the cost, while reduction on
the device level is still needed.
We provide methods and means to configure MEMS-based storage devices
to prepare them to serve in different environments as a viable storage technology.
Following our research findings, designers can craft storage systems
based onMEMS-based storage that are reliable, energy and performance efficient,
and cost effective.
Item Type:Thesis
Electrical Engineering, Mathematics and Computer Science (EEMCS)
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