FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.
Article Id 305678
Description This article explains how FortiGate performs SNMP queries to check disk usage and capacity.
Scope FortiGate SNMP.
  1. The Fortigate MIB file comes with Disk Usage and Capacity OID numbers:





  1. The SNMP response to the above query:


-----SNMP query started-----
1: fgSysDiskUsage.0 138 -> 138MB is total usage

-----SNMP query started-----
1: fgSysDiskCapacity.0 16125 -> 16125MB is total disk space


  1. Run the command 'dia sys logdisk usage' to check the total HD usage:


dia sys logdisk usage
Total HD usage: 144MB(138MiB)/16908MB(16125MiB) -> 16125MB is total disk space | 138MB is total usage
Total HD logging space: 12680MB(12093MiB) -> Total free space on log disk 
HD logging space usage for vdom "root": 5MB(5MiB)/12680MB(12093MiB) -> Used space on log disk



The total HD logging space is 12680MB(12.68GB). This is because FortiGate is using by design only 75% of the disk.

For more information refer to Technical Tip: Hard disk utilization by the FortiGate