you can delete dump files- dragonfly does not use them once loaded.
Can you please describe in more detail why you think your keys are deleted by Dragonfly? Does the whole database get flushed or just some keys?
I am not quite sure why they get deleted, its the whole db that gets emptied out
Here are the stats for my instance
it also happens randomly after a long period of time
I will check my log files the next time it happens
Please add here ‘info all’ output
Also, please attach the info log file dragonfly produces