Accession Number : AD0750672

Title :   An Analysis of Drum Storage Units.

Descriptive Note : Technical rept. no. 26,

Corporate Author : STANFORD UNIV CALIF STANFORD ELECTRONICS LABS

Personal Author(s) : Fuller,Samuel H. ; Baskett,Forest

Report Date : AUG 1972

Pagination or Media Count : 68

Abstract : The report discusses the modeling and analysis of drum-like storage units. Two common forms of drum organizations and two common scheduling disciplines are considered: the file drum and the paging drum; first-in-first-out (FIFO) scheduling and shortest-latency-time-first (SLTF) scheduling. The modeling of the I/O requests to the drum is an important aspect of this analysis. Measurements are presented to indicate that it is realistic to model requests for records, or blocks of information to a file drum, as requests that have starting addresses uniformly distributed around the circumference of the drum and transfer times that are exponentially distributed with a mean of 1/2 to 1/3 of a drum revolution. The arrival of I/O requests is first assumed to be a Poisson process and then generalized to the case of a computer system with a finite degree of multiprogramming. (Author)

Descriptors :   (*MEMORY DEVICES, MATHEMATICAL MODELS), (*DATA STORAGE SYSTEMS, SCHEDULING), QUEUEING THEORY, ALGORITHMS, STOCHASTIC PROCESSES

Subject Categories : Computer Hardware

Distribution Statement : APPROVED FOR PUBLIC RELEASE