If Logstash persistent queues are disabled, is there back pressure between Logstash and Filebeat?
In that case a small in-memory queue will be used and once this fills up back-pressure will be applied.
like @Christian_Dahlqvist said, Filebeat or any beats have a small memory queue, but you could use the spool to disk option. So when back pressure happens Filebeat will persist them to disk.
Thanks guys!