What this article covers
A memory alert that consistently overlaps a FortiGuard update window should be correlated with update timing before unrelated configuration is changed.
ScopeLower-RAM FortiGate models, including FG-40F, FG-60F and FG-80F units, where conserve-mode alerts coincide with FortiGuard update activity.
Troubleshooting workflow
Use the minimal ISDB mode
The source recommends the minimal Internet Service Database definition mode.
config system global
set isdb-optimization mini
endMove updates outside peak periods
Stagger scheduled FortiGuard signature downloads outside the busiest operating window using config autoupdate schedule.
Review unused signature packages
Evaluate whether packages such as Industrial OT/IoT signatures are required in the deployed environment before disabling anything.
Prevent overlapping update attempts
Increase update retry intervals where repeated retries could overlap database download or compilation cycles.
Compare pre-update and post-update memory
Capture memory and conserve-mode state before the update, during the event and after compilation completes.
get system performance status
diagnose hardware sysinfo memory
diagnose hardware sysinfo conserveOperational caution
Review before applying: Do not disable security content solely to reduce memory. Confirm that each package is unused and that the resulting protection level still meets policy.