After an AP performs an opportunistic or mandatory scan, a "Channel scan" event will appear on the Event log page. If the scan is opportunistic, the event details will show "active 0" whereas a mandatory scan will show "active 1". An opportunistic scan will only occur when an AP has no connected mesh APs ( "mesh_in 0", "mesh_out 0" ) or connected clients ( "clients 0" ). A mandatory scan which is configured manually by the network administrator will occur whether or not an AP has established mesh connections or connected wireless clients.
If an AP is dual band, it has two radios. Channel scans occur per radio, therefore the AP can channel scan on any radio that does not have connected clients without affecting connections on the other radio. Client connections are determined by referencing a local association table on the AP before performing an opportunistic scan.