Journal planning for Global Mirror
Journaling is important for decreasing recovery time for all high availability solutions. In the case of IBM® System Storage® based technologies, such as Global Mirror, journaling forces write operations to external storage units, which is necessary because data mirroring occurs outside of IBM i storage.
Journal management prevents transactions from being lost if your system ends abnormally. When you journal an object, the system keeps a record of the changes you make to that object. Regardless of the high availability solution that you implement, journaling is considered a best practice to prevent data loss during abnormal system outages.