Troubleshooting Tip: CLI Commands to review the cw_acd process memory usage on FortiGate

The cw_acd process is used to handle communication between FortiGate and APs. In some cases, this process can consume a lot of memory causing FortiGate to enter in conserve mode.

If high memory usage is detected by the cw_acd process, the following commands can be executed on Fortigate CLI to get information about the memory usage on this process:

fnsysctl date
get sys performance status
diag hardware sysinfo memory
diag hardware sysinfo slab
diag hardware sysinfo conserve
diag sys top-mem 30
diag sys top 5 30 6 <----- Hit 'm' to order the processes by memory usage.

get wireless-controller status
diagnose wireless wlac -c mpmt
diagnose wireless-controller wlac -c stats
diagnose wireless-controller wlac -p 0 -c stats
diagnose wireless-controller wlac -p 1 -c stats
diagnose wireless-controller wlac -p 2 -c stats
diagnose wireless-controller wlac -p 3 -c stats
diagnose wireless-controller wlac -p 4 -c stats
diagnose wireless-controller wlac -p 5 -c stats
diagnose wireless-controller wlac -p 6 -c stats
diagnose wireless-controller wlac -p 7 -c stats

Use these commands on the Teraterm script to automatically get the CLI information along a scheduled time to validate if the memory in increasing due to the cw_acd process.

In addition to the above commands, wireless global settings and timers can be modified under:

config wireless-controller global
config wireless-controller timers

As of FortiOS version 7.6.3, there are some new commands to optimize memory usage for wireless:
Offline station data consumes excessive memory when the sta-offline-cleanup or max-sta-offline settings are not configured. This is documented in the FortiOS Release Notes 7.4.5 under issue 1080094.

The following settings were added to improve memory usage:

1. Add sta-offline-ip2mac-cleanup and sta-offline-cleanup in wireless timers:

config wireless-controller timers
    set sta-offline-ip2mac-cleanup 300
    set sta-offline-cleanup 300
end

2. Add max-sta-offline-ip2mac and max-sta-offline in wireless global:

config wireless-controller global

    set max-sta-offline-ip2mac 1024

    set max-sta-offline 1024

end

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