Troubleshooting Tip: cw_acd process spikes to 99% on FortiGate Firewall

[pprince]

Description	This article describes how to resolve an issue where cw_acd, a process that handles the wireless daemon for FortiAP, gets overloaded and shows heavy CPU spikes in a large-scale FortiAP-FortiGate Controller environment. The spike can be seen on the FortiGate via the following CLI command: diagnose sys top
Scope	FortiGate/FortiAP v7.2 and above.
Solution	Configure multiple processors for the wireless daemon (cw_acd). It splits the total number of FortiAPs into smaller groups where each cw_acd process manages a group. To configure multiple cw_acd processes in the global domain, use the following FortiGate CLI command: config wireless-controller global     set acd-process-count <0-32> end The process counts the maximum values to be set as per the following table: For example, if there are 200 FortiAPs managed by a FortiGate, use set acd-process-count 4. Alternatively, kill the cw_acd process from the FortiGate CLI and check if the APs come online.  diagnose sys process pidof cw_acd  <--- This command is used to find process-id. diagnose sys kill 11 <pid> Alternatively, below command can be used as well to kill the cw_acd process: fnsysctl killall cw_acd   <--- This will kill all cw_acd processes that are running.  Note: An issue with cw_acd stuck at 99% CPU usage has been addressed in FortiOS v7.4.8/v7.6.3.