Efficient access to variable-length data on a sequential access storage medium

Abstract

A system, a method and a program product provide access to variable-length data segments on a sequential access storage medium using an iterative search for a specified data offset based on estimates of media offsets. The data is recorded in variable-length data segments aligned to predetermined alignment intervals. Each data segment has a predetermined signature field to identify the header of each data segment. Session data recorded on the medium so as to prevent session data that matches the signature field from being aligned with the predetermined alignment interval. Approximate or default parameters for data segment size are used for each estimate and are updated with each iteration based on actual data derived from data segment headers on the medium.

Description

[0001] This application is a divisional application of an invention patent application with an application date of August 18, 2000, an application number of 00128623.4, and an invention title of "Effective Access to Variable Length Data on Sequential Access Storage Medium". technical field

[0002] The present invention relates generally to sequential access storage media, and more particularly to accessing variable length data segments on sequential access storage media. Background technique

[0003] Sequential access storage media, such as magnetic tape and WORM (write once, read many) optical discs, are typically used to store large amounts of data. Sequential access storage media provides a low-cost storage alternative to other storage method options such as magnetic disks, disk arrays, or random access memory (RAM). However, a disadvantage of sequentially accessing storage media is that the process of locating a specific location on the media is relatively slow. For ma...

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