この事象を防ぐには、事前にCLIにて下記コマンドを実行し、GEOIPのDBを削除して頂く必用がございます。
# diagnose geoip delete-geoip-db
This operation will delete the Geoip Database and reboot the system!
Only super admin has the permission with the command.
Do you want to continue? (y/n)y
詳細はメーカードキュメントの下記URLをご参照下さい。
https://docs.fortinet.com/document/fortigate/6.2.12/fortios-release-notes/413989/fortigate-30e-and-50e-flash-card-space-optimization