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Efficient file allocation (Sliding secondary allocation for OS/390 datasets)

IP.com Disclosure Number: IPCOM000014208D
Original Publication Date: 2000-Nov-01
Included in the Prior Art Database: 2003-Jun-19

Publishing Venue

IBM

Abstract

This paper proposes to provide a scheme where the quantity of secondary extents allocated for OS/390 datasets increases geometrically (doubles, triples, quadruples, etc.) after some number of extents (like 10) up to a point which the maximum dataset size (1G, 2G, 4G, or 64G) can be reached with the current extent quantity within the maximum number of extents allowed on the dataset. For example, assume the case where it is desired for the secondary quantity to double after every 10 extents up to a point where the quantity no longer has to be doubled because a 2GB dataset size, can be reached within the remaining extents. Primary quantity 180 4K pages 1 cyl Initial secondary quantity 180 4K pages 1 cyl Extents Secondary quantity