n is an integer. The maximum value is 1024 (MB), and the minimum is 16 for Unicode instances and 8 for 8-bit instances. The default value is 64.
jrnbufs is the amount of memory allocated for journal buffers. Increasing this setting means increasing the amount of journal data that can be held in memory, which improves journaling performance but increases the amount of journal data that could potentially be lost in the event of a system failure.
Changing This Parameter
On the Advanced Memory page of the Management Portal (System Administration > Configuration > Additional Settings > Advanced Memory), in the jrnbufs row, select Edit. Enter a number of megabytes.
Instead of using the Management Portal, you can change jrnbufs in the Config.config 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).
If you edit this setting, you must restart InterSystems IRIS® data platform to apply the change.