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...they note the applicability of their taxonomy to powering down components on portable computers, they reported the effect of different methods only in the context of the TickerTAIP simulation system [=-=Ruemmler & Wilkes 1994-=-]. Also, they separate the prediction of when an idle period will arrive from the prediction of its duration. Adaptive Disk Spin-down Polícies for Mobile Computers 409Here, our spin-down threshold is...

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...: the Gaussian Elimination and the recalculation. 1 We do not include any equations for the time to perform disk reads/writes because the complexity of disk operation precludes a simple encapsulation =-=[25]-=-. 11 � is:sSince at leasts� ¦ rows ofs� are identity rows, the Gaussian Elimination takess§ ¦ § �ssteps. ¦ As is likely to be small this should be very fast (i.e. milliseconds). The subsequent recalcu...

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... a detailed disk model, a preliminary implementation of DiskOS, and relatively coarsegrain models of the processor and the I/O interconnect. The disk model is based on the Ruemmler&Wilkes' disk model =-=[30]-=-. We used the implementation by David Kotz [19] as the initial codebase. The disk model includes a fixed cost for the controller overhead, a seek model that models short seeks and long seeks separatel...

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...ecified in the range query, it is reasonable to assume that the set of blocks fetched can be rearranged into a number of groups of consecutive blocks by a database server or disk controller mechanism =-=[25]-=-. Since it is more efficient to fetch a set of consecutive disk blocks rather than a randomly scattered set in order to reduce additional seek time, it is desirable that objects close together in a mu...

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...and idle tasks in the TickerTAIP simulation system [Ruemmler94, Golding94]. In particular, we simulated a host system issuing read and write requests to a set of disks. We used calibrated disk models =-=[Ruemmler94]-=-, and exercised our detectors using I/O access traces taken from real systems [Ruemmler93] to avoid making simplifying assumptions about access rates. We used 1week subsets of these traces. We added a...

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... Figure 1 where 610000 and 0 132 are in units of sectors using a linear block address. Most drive performance models focus on estimating the effect of seeks, rotational delay and drive cache policies =-=[8, 7]-=-; we are also concerned with the time needed to spin-up disk drives. Although some papers have modeled spin-up performance, the models were either for laptop drives (which have different characteristi...

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... of an HP 97560 SCSI hard disk, which has an average seek time of 13.5 ms and a maximum sustained throughput of 2.2 MB/s [9]. Our implementation of the disk model was based on earlier implementations =-=[26,13]-=- 1 . Among the factors simulated by our model are head-switch 1 The source code for this disk simulator is available online at http://www.cs.dartmouth.edu/~nils/disk.html, and is distributed with 16t...