Resolution:
If you run out of disk space while writing persistent messages to disk you will get a “SEVERE ERROR” with an I/O exception on the EMS server log. The error could be differently worded for failsafe and non failsafe destinations.

On the other hand the client application would throw “javax.jms.JMSException: Failure storing message” kind of error message. Messages should not be lost if you are using Persistent delivery mode on a failsafe destination with disk caching disabled.