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Wraparound Spool File

IP.com Disclosure Number: IPCOM000043859D
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

DeForest, TN: AUTHOR [+2]

Abstract

Trace data is normally kept in storage in a wraparound table with the oldest information continually being overlaid by the most recent information. Also, using the CPTRAP command, an external trace file can be created. This external trace file is a spool file, on disk, which continually grows in size as more trace entries are added to it. When it reaches approximately 15 megabytes of data, it is closed and retained and a new file is automatically opened. If there is a large amount of tracing activity, the spool space for the whole system will eventually be exhausted. This problem of using all or very large amounts of spool space is solved by handling the trace spool file as a wraparound spool file. A new parameter can be specified on the CPTRAP command which gives the size of the wraparound trace spool file.

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Wraparound Spool File

Trace data is normally kept in storage in a wraparound table with the oldest information continually being overlaid by the most recent information. Also, using the CPTRAP command, an external trace file can be created. This external trace file is a spool file, on disk, which continually grows in size as more trace entries are added to it. When it reaches approximately 15 megabytes of data, it is closed and retained and a new file is automatically opened. If there is a large amount of tracing activity, the spool space for the whole system will eventually be exhausted. This problem of using all or very large amounts of spool space is solved by handling the trace spool file as a wraparound spool file. A new parameter can be specified on the CPTRAP command which gives the size of the wraparound trace spool file. Once the file has reached the size specified, the oldest entries will start to be overlaid by the most recent entries in a continuous fashion. The installation can thus limit the amount of spool space that will be dedicated for the trace spool file, based on the total amount of spool space available in the system and how much trace data is reasonable to keep before overlaying begins. A wraparound spool file is applied here specifically to a trace spool file. The concept, however, can be applied equally as well to any application that records data in a spool file, but only where the most recent data is actually valid or pertinent.

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