There are two criteria for rolling over log files: time and size. The default is to use a time criteria and roll over files every seven days.
To change the time interval, you need to change the property imq.log.file.rolloversecs. For example, the following property definition changes the time interval to ten days:
imq.log.file.rolloversecs=864000
To change the rollover criteria to depend on file size, you need to set the imq.log.file.rolloverbytes property. For example, the following definition directs the broker to rollover files after they reach a limit of 500,000 bytes
imq.log.file.rolloverbytes=500000
If you set both the time-related and the size-related rollover properties, the first limit reached will trigger the rollover. As noted before, the broker maintains up to nine rollover files.
You can set or change the log file rollover properties when a broker is running. To set these properties, use the imqcmd update bkr command.