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Browse Prior Art Database

Device Level Selection

IP.com Disclosure Number: IPCOM000044118D
Original Publication Date: 1984-Nov-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Hamdani, SZ: AUTHOR [+3]

Abstract

This article describes an apparatus for accessing n-1 DASD (direct-access storage device) devices when one device is otherwise busy, each DASD having at least two dispatchable arms, the combination comprising: a first and second interface through which device selection signals are super-imposable; n DASD partitioned into n modulo m(n>M) sets; and a first and second path for accessing the DASD in each set, each first or second path terminating respectively in the first or second interface at one end and in a first or second arm of each DASD in a set at the other end; whereby upon a first DASD being selected by way of a first path, then the non-busy DASD of that set is selectable over the second path with the DASD of all other sets being selectable over either path. The figure shows a typical dual-port configuration.

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Device Level Selection

This article describes an apparatus for accessing n-1 DASD (direct-access storage device) devices when one device is otherwise busy, each DASD having at least two dispatchable arms, the combination comprising: a first and second interface through which device selection signals are super-imposable; n DASD partitioned into n modulo m(n>M) sets; and a first and second path for accessing the DASD in each set, each first or second path terminating respectively in the first or second interface at one end and in a first or second arm of each DASD in a set at the other end; whereby upon a first DASD being selected by way of a first path, then the non-busy DASD of that set is selectable over the second path with the DASD of all other sets being selectable over either path. The figure shows a typical dual-port configuration.

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