Performance of an I/O Channel with Multiple Paging Drums. (Digest Edition).
Technical rept. no. 27,
STANFORD UNIV CALIF STANFORD ELECTRONICS LABS
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For rotating storage units, a paging drum organization is known to offer substantially better response time to IO requests than is a more conventional file organization. When several, asynchronous paging drums are attached to a single IO channel, however, much of the gain in response time due to the paging organization is lost this article investigates the reasons for this loss in performance. A model of an IO channel with multiple paging drums is presented and a Markov chain that closely approximates the behavior of the IO channel is embedded into the model. The analysis then leads to the moment generating function of sector queue size and the Laplace-Stieltjes transform of the waiting time. A significant observation is that the expected waiting time for an IO request to a drum can be divided into two terms one independent of the load of IO request to the drum and another that monotonically increases with increasing load. Modified author abstract
- Computer Hardware