The diag sys logdisk usage command allows you to view detailed information about how much space is currently being used for logs. This is useful when you see a high percentage, such as 92 percent for the disk’s capacity. The FortiGate unit uses only 75 percent of the available disk capacity to avoid a high storage amount so when there is a high percentage, it refers to the percentage of the 75 percent that is available. For example, 92 percent of the 75 percent is available.

The following is an example of what you may see when you use diag sys logdisk usage command on a unit with no VDOMs configured:

The following appears: