What does it mean when the Log Database page shows partitions in red?

You can configure the Log Database to automatically delete partitions when they pass a specified age. Manage this option on the Settings > Reporting > Log Database page in the Web Security module of the Forcepoint Security Manager, under Database Maintenance.

When this option is enabled and a partition exceeds the specified automatic deletion age, the partition is listed in red in the Available Partitions list to indicate that automatic deletion is pending. The age of the partition is based on its end date (not its start date).

The next time the maintenance job runs, the partition will be deleted.

If you don't want the partition to be deleted, you can either increase the age at which partitions are deleted, or disable the automatic deletion option.