Browse Prior Art Database

Media Directory with Improved First Access to Fragmented Data

IP.com Disclosure Number: IPCOM000038212D
Original Publication Date: 1989-Dec-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Friedl, TJ: AUTHOR [+4]

Abstract

A media directory modification allows more rapid initial access to the data files stored on the media. This is achieved while continuing to allow the unlimited fragmentation of data by using a list of actual data locations (extents) on the media. This technique also retains the use of a fixed size directory entry, with a pointer to the start of the list of data allocations, or extents, actually occupied by the data.

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Media Directory with Improved First Access to Fragmented Data

A media directory modification allows more rapid initial access to the data files stored on the media. This is achieved while continuing to allow the unlimited fragmentation of data by using a list of actual data locations (extents) on the media. This technique also retains the use of a fixed size directory entry, with a pointer to the start of the list of data allocations, or extents, actually occupied by the data.

Most media directories include a pointer to a list of locations where the file data is actually stored (an extent list). The modification adds another pointer in the directory entry. This added pointer points to the first data area occupied by the file. See the figure for a diagram of a directory entry and the related areas on the media.

The additional pointer in the directory means that it is possible to access data with one less seek and read required. This permits the first read to begin transferring the desired data instead of the second. Furthermore, the first data read and the read of the list of data locations can be started in parallel.

Disclosed anonymously.

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