Browse Prior Art Database

AFFINITY File Allocation

IP.com Disclosure Number: IPCOM000039490D
Original Publication Date: 1987-Jun-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Brown, LG: AUTHOR [+2]

Abstract

A way is provided for an end user (with little or no knowledge of the underlying space allocation algorithms) to place a file close to another file in order to minimize disk seek times. This needs to be done without having to do file placement by location, thereby eliminating fragmentation and the need for disk compression. The user is allowed to specify an "AFFINITY" parameter on a file allocation where the user specifies the name of a file that the new file is to be allocated "close to". A system file allocation component searches for appropriate free space closest to the "AFFINITY" file using existing allocation algorithms. This has the desired effect of allocating the files close together for shortened seek distances while not allowing arbitrary file placement to cause fragmentation and hinder free space recombination.

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AFFINITY File Allocation

A way is provided for an end user (with little or no knowledge of the underlying space allocation algorithms) to place a file close to another file in order to minimize disk seek times. This needs to be done without having to do file placement by location, thereby eliminating fragmentation and the need for disk compression. The user is allowed to specify an "AFFINITY" parameter on a file allocation where the user specifies the name of a file that the new file is to be allocated "close to". A system file allocation component searches for appropriate free space closest to the "AFFINITY" file using existing allocation algorithms. This has the desired effect of allocating the files close together for shortened seek distances while not allowing arbitrary file placement to cause fragmentation and hinder free space recombination. The figure shows examples of old methods and the new method for file allocation. The large boxes represent an entire disk, while the sub-boxes represent disk extents. The boxes marked with X's are free space extents. The example assumes that a user is attempting to allocate file "B" which, for performance reasons, should be allocated close to file "A" (represented by the sub-box with A's in it).

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