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Anticipation of Data Set Expansion

IP.com Disclosure Number: IPCOM000050719D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Dey, RW: AUTHOR [+2]

Abstract

This article describes a method for reducing exposure to abnormal terminations of transactions performing inserts of data to data sets because free space is not available to extend the data set. The method comprises the steps of establishing a hedge quantity, and a secondary allocation quantity; periodically comparing the quantity of unused allocated space in the data set to the hedge quantity; responsive to the unused allocated space becoming less than the hedge quantity, attempting to extend the data set based on the secondary allocation quantity, and issuing an early warning message to a user if that attempt fails.

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Anticipation of Data Set Expansion

This article describes a method for reducing exposure to abnormal terminations of transactions performing inserts of data to data sets because free space is not available to extend the data set.

The method comprises the steps of establishing a hedge quantity, and a secondary allocation quantity; periodically comparing the quantity of unused allocated space in the data set to the hedge quantity; responsive to the unused allocated space becoming less than the hedge quantity, attempting to extend the data set based on the secondary allocation quantity, and issuing an early warning message to a user if that attempt fails.

A Data Base Management System (DBMS) implementing the method anticipates the need for data set expansion on the basis of a "hedge" quantity which may be, optionally, user specified. This is done to assist the installation in the avoidance of unscheduled interruptions to online service triggered because the free space needed to extend the data set is unavailable in a demand situation (transactions attempting to insert new records to the data set and all currently allocated space used up). If the growth of the data set causes the remaining allocated space to fall to or below the "hedge" quantity specified, then an atempt is made to extend the data set (by its secondary allocation quantity) in advance of actual need. If the attempt fails, then an "early warning" message is issued indicating the anticipated need for additional packs or spindles.

An important feature of this function is that the additional free space is actually allocated to the data set (if available) at the time that the remaining allocated space is detected to be equal to or less than "hedge" qu...