At 3.39am this morning, one of my customer's systems stopped with an error:

2017-07-14 03:39:17 NOT ENOUGH FREE DISK SPACE TO SAFELY CONTINUE
2017-07-14 03:39:17 The limit is 100MB, currently there is 0MB free, add the parameter "--disable-freespace-check" to run anyway. This is NOT recommended as it endangers all your data.
2017-07-14 03:39:17 The system will now shut down.
2017-07-14 03:39:17 Exit

It then restarted and displayed the same message again, then shut down.


When the customer started up the clients this morning, they said "Please wait, we are launching your server". My Standard showed the system as Starting. However it was not starting. I clicked Restart and it started their system without any issues.

I checked the server and there's over 100Gb of free space. None of the other filesystems are out of space either. Any idea why this message occurred and how to prevent it happening in future?