According to http://www.rsyslog.com/doc/queues.html (under "Limiting the Queue Size"), we should be setting "$<object>QueueMaxDiskSpace", and not ActionQueuSize.
According to http:// www.rsyslog. com/doc/ queues. html (under "Limiting the Queue Size"), we should be setting "$<object> QueueMaxDiskSpa ce", and not ActionQueuSize.