In most cases the hard disks on your FortiGate unit should be formatted with one partition that is used for WAN optimization and Logging and Archiving. If for some reason the hard disk is not formatted you can use the following information to format it. In some cases you might also want to use the following options to erase all data from the hard disk by reformatting it.

From the web‑based manager go to System > Config > Advanced > Disk Management to display information about the hard disk or disks available to the FortiGate unit. To format a hard disk, select the format icon. The hard disk format takes a few minutes and the FortiGate unit restarts after formatting is complete.

Fro this web‑based manager page you can also view and change the WAN optimization and Web Cache Storage size and view how much of the WAN optimization and web cache storage has been used.

From the CLI you can use the following command to view the current disk format and partition status. See the following example for a FortiGate-51B unit.

You can use the following command to reformat the hard disk. Use this command if for some reason the disk is not formatted correctly. The command includes the device partition reference number (256) so formats the entire disk and not just the partition.

You can use the following command to reformat the partition. The command includes the partition reference number so formats the partition, removing add data from it. You can use this command to delete all data from the partition and to fix partition errors.