Alert: Possible Data Integrity Issues after Adding Mirrored Database

InterSystems has corrected a defect that can result in data integrity issues on systems using mirroring.

This defect affects:

• All currently released versions of InterSystems IRIS and IRIS for Health, except 2020.1
• Caché and Ensemble versions beginning with 2011.1.1
• All HealthShare products based on the above Data Platforms versions

This defect is more likely to be encountered in IRIS and IRIS for Health 2019.4. It is highly unlikely to have occurred on deployed systems running any other version.

The issue can only occur in a situation that meets all of the following conditions:

1. A database is removed from a mirror
2. A database is added to the same mirror – this can be the same database or another one
3. There is no journal switch between removing the first database and adding the second one.

If a system encounters the defect, then the current journal file will be intact on the primary system where the database was added, but a small subset of updates in that journal file will be missing from the newly added mirrored database on all other mirror members – both failover and async members. All updates from subsequent journal files are correctly dejournaled.

There is no way to definitively determine if the defect has been encountered, but you can use the DataCheck utility to confirm the consistency of a mirror set. For more information about DataCheck, see the “ Data Consistency On Multiple Systems” section of the Data Integrity Guide.

The correction for this defect is identified as HYY2390 and will be included in all future product releases. It is also available by requesting an Ad hoc distribution from the InterSystems Worldwide Response Center (WRC).

If you have any questions regarding this alert, please contact the Worldwide Response Center.