Chapter 15 Unified Threat Management for FortiOS 5.0 : Other Security Profiles considerations : Conserve mode : Conserve mode effects : off
  
off
The off setting forces the FortiGate unit to stop all traffic that is configured for content inspection by Security Profiles features that use the AV proxy. New sessions are not allowed but current sessions continue to be processed normally unless they request more memory. Sessions requesting more memory are terminated.
For example, if a security policy is configured to use antivirus scanning, the traffic it permits is blocked while in conserve mode. A policy with IPS scanning enabled continues as normal. A policy with both IPS and antivirus scanning is blocked because antivirus scanning requires the AV proxy.
Use the off setting when security is more important than a loss of access while the problem is rectified.