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A Quantitative Analysis of Disk Drive Power Management in Portable Computers
 

Summary: A Quantitative Analysis of Disk Drive Power Management in
Portable Computers
Kester Li, Roger Kumpf, Paul Horton, and Thomas Anderson
Computer Science Division
University of California
Berkeley, CA 94720
Abstract
With the advent and subsequent popularity of portable computers, power management of
system components has become an important issue. Current portable computers implement
a number of power reduction techniques to achieve a longer battery life. Included among
these is spinning down a disk during long periods of inactivity. In this paper, we perform a
quantitative analysis of the potential costs and benefits of spinning down the disk drive as
a power reduction technique. Our conclusion is that almost all the energy consumed by a
disk drive can be eliminated with little loss in performance. Although on current hardware,
reliability can be impacted by our policies, the next generation of disk drives will use technology
(such as dynamic head loading) which is virtually unaffected by repeated spinups. We found
that the optimal spindown delay time, the amount of time the disk idles before it is spun down,
is 2 seconds. This differs significantly from the 35 minutes in current practice by industry. We
will show in this paper the effect of varying the spindown delay on power consumption; one
conclusion is that a 35 minute delay results in only half of the potential benefit of spinning

  

Source: Anderson, Tom - Department of Computer Science and Engineering, University of Washington at Seattle

 

Collections: Computer Technologies and Information Sciences