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Temporary Error Forcing Technique

IP.com Disclosure Number: IPCOM000038071D
Original Publication Date: 1989-Oct-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Graham, CS: AUTHOR [+3]

Abstract

To adequately test software which interfaces to a diskette drive it is necessary to include tests of temporary, or recoverable, errors. Previously this has been done using various hardware tools to cause an error at a particular time. A new technique was developed to easily cause temporary diskette errors without requiring additional hardware.

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Temporary Error Forcing Technique

To adequately test software which interfaces to a diskette drive it is necessary to include tests of temporary, or recoverable, errors. Previously this has been done using various hardware tools to cause an error at a particular time. A new technique was developed to easily cause temporary diskette errors without requiring additional hardware.

To cause a temporary error, first write all records on a track of the media (with the same record ID field). Next, it is necessary to cause an error in at least one of the records. This could be done when the records are written by purposely writing a bad record. Alter- natively, sweeping a small magnet across a selected portion of the diskette should cause one or two records to be damaged. This is shown pictorially in the figure.

In the figure all records on a track have been written as if they were logical record number 3. The record which is physically the fourth record on the track has an incorrect check field following the data.

The next step is simply to repeatedly read the record number written to the media previously. Assuming an example of 15 records per track, on the average, 1 read in 15 will encounter the bad record. Now that the error was detected, the error recovery code will execute and sooner or later retry the operation. At this point the retry will "probably" succeed since it will most likely find one of the good records.

It is true that this method is not absolutely deter...