Technical Tip: Understanding CPU Utilization Difference Between FortiGate and Azure

Description

This article describes the difference in CPU utilization metrics between FortiGate and Azure. The user may notice a discrepancy in CPU usage between the two platforms, which can be attributed to the way each system measures CPU usage.

Scope

FortiGate-Azure, FortiGate-VM.

Solution

To understand the difference in CPU utilization between FortiGate and Azure metrics, it is essential to know how each system measures CPU usage.  

FortiGate measures CPU usage based on FortiOS processes, including firewall, IPS, SSL inspection, routing, sessions, and kernel security inspection workload.

On the other hand, Azure VM CPU metric measures hypervisor-level CPU consumption among the entire VM usage seen by the Azure host. The difference in CPU utilization can be expected due to the redistribution of vCPUs from Azure Hypervisor to FortiGate.

To verify this:        

1. Check the CPU usage on both FortiGate and Azure platforms.        

2. Compare the CPU usage metrics to identify any discrepancies.        

3. Understand that the difference in CPU utilization is due to the different methods of measurement used by each system and is, in fact, expected.