pfSense

The disk on our SG-3100 recently filled up to 100%. The only symptom was that the DNS Resolver service failed, meaning it could no longer service DNS requests. Upon trying to re-start it, the service logged errors about failing to read the root.key and despite successful attempts to delete and re-create the file, it kept wiping the file upon the next start of the service and reporting the same errors again.
Eventually we realised and cleared some disk space and the service re-started OK.

Two suggestions come from this:
1) Can the DNS Resolver service not log something more useful if it fails to start due to a disk space issue?
2) Although the home page does indeed show the disk usage at 100%, could this event, which could affect many other services in unpredictable ways, not be highlighted to the user in a more obvious way; a pop-up alert maybe?