You can change the setting (alert only, not the threshold where the DR actually goes into read only mode) from 70-90%
https://support.quest.com/technical-documents/dr-series-software/4.0.3.1/command-line-reference-guide/44#TOPIC-908071
system --storage --set_usage_alert 80
This won’t functionally change anything except when you get the alert.
You can check current setting with just system --show
• Storage Usage Alert : 90%