How to reduce memory usage in FortiGate firewall

  • FortiGate firewalls are widely used in network security infrastructures to protect against cyber threats and ensure data safety.
  • These firewalls work efficiently, but sometimes their memory usage can become a concern, especially for organizations with resource-constrained devices.
  • High memory usage can lead to performance issues, affecting the overall security and functionality of the FortiGate firewall.
  • In this article, we will explore essential techniques and best practices to reduce memory usage in FortiGate firewalls.

Understanding Memory Usage in FortiGate Firewall

Memory Management in FortiGate Firewall

  • FortiGate firewalls handle a wide range of security features, including firewall policies, VPNs, antivirus scanning, intrusion prevention systems (IPS), web filtering, and more.
  • Each of these features requires memory allocation for storing data and processing packets efficiently.
  • Proper memory management is crucial for optimized performance.

Factors Affecting Memory Usage

Several factors contribute to high memory usage in FortiGate firewalls. These include:

  • Traffic Volume: High network traffic can consume significant memory resources, especially during peak hours.
  • Security Profiles: Intensive use of antivirus, IPS, and other security profiles can impact memory usage.
  • Connection Limits: Configuring a high number of connection limits may strain the firewall’s memory.
  • Logging: Extensive logging can consume memory space, particularly if not adequately managed.

Techniques to Reduce Memory Usage

3.1. Traffic Optimization

  • Traffic optimization is essential to reduce memory usage in FortiGate firewalls.
  • Consider implementing Quality of Service (QoS) policies to prioritize critical traffic and limit bandwidth for non-essential services.

3.2. Connection Limits

  • Carefully set connection limits to prevent excessive memory usage due to connection handling.
  • Analyze your network’s requirements and adjust connection limits accordingly.

3.3. Session Timeout Settings

Configure appropriate session timeout settings to release idle sessions and free up memory resources.

3.4. Proxy Options

  • FortiGate firewalls offer various proxy options, such as explicit proxy and transparent proxy.
  • Choose the appropriate proxy mode to optimize memory usage.

3.5. Anti-Virus and IPS Profiles

  • Review the usage of antivirus and IPS profiles and fine-tune them to match your network’s needs.
  • Disable unnecessary signatures or use a higher-level scanning only for specific traffic.

3.6. Reducing Logging

Evaluate your logging settings and consider reducing the amount of data logged, especially for routine activities.

3.7. Firmware Updates

  • Ensure that your FortiGate firewall is running the latest firmware version.
  • Firmware updates often include memory optimization enhancements.

Monitoring Memory Usage

4.1. FortiGate’s Built-in Monitoring Tools

  • FortiGate firewalls come with built-in monitoring tools that allow you to track memory usage in real-time.
  • Regularly check these tools to identify any memory-related issues promptly.

4.2. Third-Party Monitoring Solutions

Consider using third-party monitoring solutions that offer more comprehensive memory usage analysis and alerting capabilities.

Best Practices for Memory Management

5.1. Right-sizing the Hardware

Select the appropriate FortiGate model based on your network’s requirements to ensure sufficient memory capacity.

5.2. Regular Maintenance

Perform regular maintenance tasks, such as cleaning up old logs and sessions, to keep memory usage in check.

5.3. Optimal Configuration

Work closely with your network security team to optimize firewall configurations based on your specific needs, striking the right balance between security and memory usage.


Efficient memory management is vital for the optimal performance of FortiGate firewalls.

By implementing the techniques discussed in this article and adhering to best practices, you can reduce memory usage and enhance the overall security and functionality of your FortiGate firewall.


Q1. How do I get FortiGate out of conserve mode?

To get FortiGate out of conserve mode, you need to address the underlying resource utilization issue that triggered conserve mode in the first place.

Q2: What is FortiGate conserve mode?

  • FortiGate conserve mode is a feature implemented in FortiGate firewalls to preserve system resources during high utilization periods.
  • When enabled, conserve mode optimizes memory and CPU usage by temporarily suspending non-essential processes, allowing critical functions to continue operating efficiently.

Q3: When does FortiGate enable conserve mode?

  • FortiGate automatically triggers conserve mode when it detects that system resources, such as CPU or memory, are reaching their maximum capacity.
  • The firewall activates conserve mode to prevent a complete system outage or performance degradation