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Browse Prior Art Database

Mapping of a Multi-Level Directory Structure to Optical Media

IP.com Disclosure Number: IPCOM000037284D
Original Publication Date: 1989-Dec-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 3 page(s) / 67K

Publishing Venue

IBM

Related People

Hoag, TM: AUTHOR [+4]

Abstract

Described is a method of supporting a multi-level naming structure where any given folder or subdirectory in a System/36 may contain data objects on multiple volumes while requiring at most one volume mount to find any specific data object. This addresses problems associated with searching through multiple optical volumes to locate an object leading to excessive overhead and time due to the movement of the media within a mass optical storage device (MOSD). In addition, limiting the number of volumes accessible through a single folder requires significantly more direct access storage device (DASD) overhead then a solution where multiple volumes are accessed through a single folder. (Image Omitted)

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Mapping of a Multi-Level Directory Structure to Optical Media

Described is a method of supporting a multi-level naming structure where any given folder or subdirectory in a System/36 may contain data objects on multiple volumes while requiring at most one volume mount to find any specific data object. This addresses problems associated with searching through multiple optical volumes to locate an object leading to excessive overhead and time due to the movement of the media within a mass optical storage device (MOSD). In addition, limiting the number of volumes accessible through a single folder requires significantly more direct access storage device (DASD) overhead then a solution where multiple volumes are accessed through a single folder.

(Image Omitted)

The method maps a multi-level naming structure to optical volumes by first separating a complete path name from an object name. The complete path name consists of a folder name and each level of subdirectory within that folder. These objects within this path are then mapped to an optical volume. All of the objects within that path are stored on that optical volume, however, there are not any subdirectory pointers stored on the volume. This differs considerably from other implementations of multi-level name structures where a given directory must exist on the same volume as the path it is contained within.

A DASD table, called the Path-Volume Relationship (PVR) table, is maintained with an entry for every path. Included in this entry is the name of the optical volume that contains the related path. This approach allows the physical optical volume to be located in one search of the DASD table of paths. Next, the optical volume is mounted to an optical drive, and the directory of objects is searched to find the address of the data object. This requires a single mount of the required optical vol...