Discovery server showing following warning "28 Jan 2019 12:23:38,679 [Thread-73 (HornetQ-client-global-threads-933869191)] WARN org.hornetq.core.client - HQ212037: Connection failure has been detected: HQ119015: The connection was disconnected because of server shutdown [code=DISCONNECTED]"
When the queue exceeds the threshold (queue_growth_size = 10 MB default), an alarm is sent.
Goto hub.cfg file, check for "queue_growth_size =" but the default is 10MB. This is the hub bulk warning in the hub.cfg Alarm on queue size - the size of the queue file (in MB) on the hub. If the queue exceeds this threshold, an alarm is sent. As a best practice support suggest this value be raised to a minimum of 300. In large environments, this should usually be 500 - 750.