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Multi-Route Access .to Information Stored on Rotating-Mass-Storage Devices by

IP.com Disclosure Number: IPCOM000128501D
Original Publication Date: 1971-Dec-31
Included in the Prior Art Database: 2005-Sep-16
Document File: 19 page(s) / 60K

Publishing Venue

Software Patent Institute

Related People

N. Minsky: AUTHOR [+3]

Abstract

This paper explores the feasibility bf improving the conventional techniques of organizing information on rotating storage devicesfby utilizing the fact that "head switching" is a very fast electronic operation. It is shown that proper usage of this virtually unused. capability considerably enhances the effectiveness of the rotating devices as a medium for storing complex structures. Techniques for organizing several popular data structures are discussed in some detail. It is shown, for example, that the proposed access method can considerably improve the efficiency of manipulating structures like trees, large matrices, indices, and files. Problems involved with implementation of the proposed access method under general-.purpose operating syst-ams are. also discussed.

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THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

Multi-Route Access .to Information Stored on Rotating-Mass-Storage Devices by

N. Minsky*

Technical Report 71-1 December.1971

*on leave from the Hebrew University of Jerusalem.

Abstract

This paper explores the feasibility bf improving the conventional techniques of organizing information on rotating storage devicesfby utilizing the fact that "head switching" is a very fast electronic operation. It is shown that proper usage of this virtually unused. capability considerably enhances the effectiveness of the rotating devices as a medium for storing complex structures. Techniques for organizing several popular data structures are discussed in some detail. It is shown, for example, that the proposed access method can considerably improve the efficiency of manipulating structures like trees, large matrices, indices, and files. Problems involved with implementation of the proposed access method under general-.purpose operating syst-ams are. also discussed.

Introduction

The rotating mass storage devices, although frequently referred to as "random access" are never really treated as such. The name "semi-sequential devices" would more accurately reflect the techniques used to organize information on them. The disc storage space is essentially used in two modes: the "random mode" with its relatively long access-time (typically 150 ms; per probe),and the "sequential mode" which enables us to gain access to a sequence of sectors, along a track, in the bigh disc transfe'r-rate. The use of these two as the basic modes of disc access, introduces an order,into any information stored on a disc. This so called "sequential order", is the order inwhich the information is re recorded along tracks, and it is believed to be th e only order in which information is accessible with maximum efficiency. The exi stence of a single rapidly-accessible order of information, obviously places a severe restriction on our ability to efficiently organize'complex information on discs.

We believe, however, that there is no inherent reason to restrict ourselves to a single "seguential-order". We will try to show in this paper that the fundamental hardware properties of rotating-mass-storage devices allow access to the storage space of their cylinders in many different routes without any loss of efficiency.

The implications of this ability to techniques for organizing information on discs are remarkable. It turns out that many data

(1) We will use the term disc in this paper to represent the general family of rotating mass storage devices. structures can be organized much more efficiently by utilizing the multi-route access to the disc storage space. Those improvements can be achieved virtually with no

University of Minnesota Page 1 Dec 31, 1971

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Multi-Route Access .to Information Stored on Rotating-Mass-Storage Devices by

hardware changes! what is needed is mainly some conceptual reorientation....