System Settings : Configuring general settings : Configuring RAID : Adding new disks for FMG-2000B and FMG-4000B
 
Adding new disks for FMG-2000B and FMG-4000B
The FMG-2000B unit is shipped with two hard disks. You can add up to four more disks to increase the storage capacity. The FMG-4000B unit is shipped with six hard disks. You can add up to 18 more disks to increase the storage capacity.
 
Fortinet recommends that you use the same disks as those supplied by Fortinet. Disks of other brands will not be supported by Fortinet. For information on purchasing extra hard disks, contact your Fortinet reseller.
To add more hard disks
1. Obtain the same disks as those supplied by Fortinet.
2. Back up the log data on the FMG-2000B/FMG-4000B unit. You can also migrate the data to another FortiManager unit if you have one. Data migration reduces system down time and risk of data loss.
For information on data backup, see “Backing up the configuration”.
3. Install the disks on the FortiManager unit. You can do so while the FortiManager unit is running.
4. Configure the RAID level. See “Configuring RAID”.
5. If you have backed up the log data, restore the data. For more information, see “Restoring the configuration”.
See also 
Viewing RAID status
Replacing hard disks
Configuring RAID