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Browsing by Subject "data retrieval"

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    Coping with Excessive Memory Requirement Under I/O Bandwidth Congestion
    (1997) Won, Youjip; Srivastava, Jaideep
    In this paper, we investigate the buffer requirement in retrieving the continuous media streams from the disk subsystem. Memory buffer is used to synchronize asynchronous disk read operation and synchronous playback operation. In supporting a set of continuous media playbacks, as aggregate bandwidth required increases, larger amount of buffer needs to ibe allocated. This characteristics originates from the increase in cycle length. It is well known fact that as disk utilization approaches I 00%, total buffer to support the playbacks increases extremely fast. Conservative estimation on disk usage is thus advised in designing disk subsystem for continuous media server. However, in the practical situation aggregate bandwidth may increase over the expected value, and may consume excessive amount of buffer memory. The focus of this is to an algorithm coping with this excessive buffer requirement under bandwidth congestion. We argue that in a large scale continuous media server, where user access pattern is biased and there are frequent request arrivals, it is not necessary to maintain the playback directly from the disk for each request in supporting a set of timely interleaved playbacks. We define two mechanisms to service a playback request, namely disk mode and memory mode. In memory mode, request is supplied data blocks which was loaded by preceding request. We develop an efficient algorithm to determine the optimal service mode for a set of playback request minimizing overall buffer requirement.
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    Information Circular 9. Instructions for Using the Minnesota System for Storage and Retrieval of Geologic Log Data
    (Minnesota Geological Survey, 1971) Mossler, John; Winter, T.C.; Tufford, Sarah
    Information on geologic formations has always been needed by government agencies, industries, and individuals interested in mineral and water resources. Increasing interest in these resources and in the growing environmental problems caused by underground storage of materials and waste disposal has created a need for ready access to geologic data. Several government agencies in Minnesota collect a large amount of geologic data. Until the present time each agency maintained its own file, although exchange of data has occurred often and freely. However, to avoid duplication of effort and to establish the most efficient data storage and retrieval system it was decided that the Minnesota Geological Survey would maintain the central file of geologic data for the State and that the data should be stored in a digital computer system. A printout would then be provided of whatever geologic data was requested by other agencies and individuals. The first need in establishing a system for computer processing of geologic data is to store geologic logs on machine-readable punched cards. The purpose of this report is to provide instructions for recording and coding geologic log data in such a manner that it can be punched by keypunch operators.