DocumentCode :
1148641
Title :
Models of DASD Subsystems with Multiple Access Paths: A Throughput-Driven Approach
Author :
Brandwajn, Alexandre
Author_Institution :
Amdahl Corporation
Issue :
5
fYear :
1983
fDate :
5/1/1983 12:00:00 AM
Firstpage :
451
Lastpage :
463
Abstract :
A throughput-driven approach to the performance analysis of direct access storage devices (DASD´s), i.e., disks, is presented for a model of a block-multiplexor channel system with multiple transfer paths. The approach relies on a step-wise analysis of shared components within the data transfer path: head of string, control unit, channel, referred to as blocking points. In order to derive the service time of an I/O request, each blocking point is analyzed separately, using essentially a classical loss-system model. The advantages of the method are its relative simplicity and applicability to a large number of configurations. Transient and boundary effects, including the miss probability on second and subsequent reconnection attempts, and the device reconnection window (lead time), are also discussed. The inclusion of the approach in a larger system model, as well as its relationship with previous work on DASD analysis is considered. Numerical results illustrate the accuracy of the method.
Keywords :
Analytical models; block-multiplexor channels; disk subsystems; dual ports; missed reconnections; multiple transfer paths; reconnection window; shared control units; string switching; system model; Arm; Delay effects; Hardware; Performance analysis; Queueing analysis; Throughput; Analytical models; block-multiplexor channels; disk subsystems; dual ports; missed reconnections; multiple transfer paths; reconnection window; shared control units; string switching; system model;
fLanguage :
English
Journal_Title :
Computers, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9340
Type :
jour
DOI :
10.1109/TC.1983.1676256
Filename :
1676256
Link To Document :
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