Integrity Check False Positives
Running an integrity check on a volatile database may result in the false reporting of database integrity errors due to ongoing database updates.
When an integrity check is executed from the Management Portal or by the Task Manager, as described in Checking Database Integrity Using the Management Portal, it runs in the background, and automatically retests any globals in which errors are detected. Output from an integrity check that includes this automatic second pass reports on errors in the following manner:
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If an error was detected in a global in the first pass but not in the second pass, the first error is assumed to be a false positive and no error is reported.
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If the error detected in a global in the second pass differs from the error detected in the first pass, only the second-pass error is reported, with the text These errors in global <global_name> differ from the errors prior to the retry.
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If the same error is detected in a global in both passes, the error is reported with the message When retried the errors in global <global_name> remained unchanged.
Integrity checks executed manually using the ^Integrity utility or one of the entry points described in Checking Database Integrity Using the ^Integrity Utility do not retest globals reporting errors on the first pass. If errors are returned, repeat the check for that particular database.
Generally, for an integrity check run on an active system, errors that are not repeated in a second pass are false positives, while errors that persist in a second pass represent actual integrity problems. The latter must be investigated, and the former may merit investigation as well, depending on the level of activity, the number of errors, and the extent to which false positives have previously occurred. The nature of your investigation will depend on your level of expertise and past experience of false positives. Steps you can take include:
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Running the integrity check again, if possible during a period of lower system activity.
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Running an integrity check on a restored copy of the most recent backup.
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Examining the range of data in question for clues to the root problem.
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Contacting the InterSystems Worldwide Response Center (WRC)Opens in a new tab for assistance.
The problem of false positives can be avoided by integrating integrity checks into your standard backup procedures, such as those described in External Backup, so that databases are checked immediately after taking a snapshot of the logical disk volume on which they reside, in isolation from production as described in Isolating Integrity Checks.
