n is an integer in the range 0—10. The default value is 2.
BackupsBeforePurge defines when InterSystems IRIS purges a finished journal file (that is, a journal file that is no longer in progress). The value n is a number of successful InterSystems IRIS instance backups that must take place before the corresponding journal files can be purged.
BackupsBeforePurge relates to DaysBeforePurge. If both are greater than 0, files are purged after n days or n successful backups, whichever indicates the shorter time period. If BackupsBeforePurge is 0, purging is done solely based on DaysBeforePurge; if DaysBeforePurge is 0, then purging is done solely based on BackupsBeforePurge. If both are 0, the automatic purging of journal files (and journal history) is disabled and journal files are not purged.
No journal file containing currently open transactions is purged, even if it meets the above criteria.
For details about journal files, see the “Journaling” chapter in Data Integrity Guide.
Changing This Parameter
On the Journal Settings page of the Management Portal (System Administration > Configuration > System Configuration > Journal Settings), in the When to purge journal files category, choose one of the following:
To purge journal files based on a number of days, choose After this many days and enter a number of days.
To purge journal files based on a number of backups, choose After this many successive successful backups and enter a number of backups.
Instead of using the Management Portal, you can change BackupsBeforePurge in the Config.Journal class (as described in the class reference) or by editing the CPF in a text editor (as described in the Editing the Active CPF section of the “Introduction to the Configuration Parameter File” chapter in this book).