Browse Prior Art Database

Logical Cylinder Block Formatting

IP.com Disclosure Number: IPCOM000075899D
Original Publication Date: 1971-Dec-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Martin, RW: AUTHOR

Abstract

In block formatting schemes for data storage devices, it is desirable to make interblock gaps as narrow as possible to increase capacity. However, as gaps are made narrower, less time is available therein for system turnaround, head switching, and the like.

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Logical Cylinder Block Formatting

In block formatting schemes for data storage devices, it is desirable to make interblock gaps as narrow as possible to increase capacity. However, as gaps are made narrower, less time is available therein for system turnaround, head switching, and the like.

The described scheme solves this problem by providing offset logical blocks on adjacent physical tracks of a cylinder. Thus, system turnaround time and head switching can occur concurrently over data, eliminating the need for providing time for these functions in the interblock gaps.

In the example shown in the drawing, four physical tracks comprise one logical track. The four physical tracks are divided into blocks with their gaps offset by a quarter block from the previous block. Block assignments would follow the sequence shown. Arrows show the transition from the end of one block to the start of the following block. For example, data could be read or written in blocks 1, 2, 3, ... with system turnaround and head switching occurring during the leading one quarter of blocks 21, 22, 23, ..., respectively. The format may be expanded by offsetting logical tracks in sequence and developing a logical cylinder. The number of rotations required to read or write a logical track will be the number of physical tracks in the logical track plus one.

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