Drives are at risk of running out of free space (SharePoint Server)
APPLIES TO: 
2013 2016 2019 Subscription Edition 
SharePoint in Microsoft 365
Rule Name: Drives are at risk of running out of free space.
Summary: This rule checks disk space as a proportion of the RAM that is installed on the SharePoint Server. Servers with large amounts of RAM are more likely to experience a failure of this rule.
Cause: When disk space is less than five times the RAM on the server, this health rule triggers a warning. For example, if your SharePoint Server has 16GB of RAM installed, the rule checks for 80GB of free space on the disk.
Resolution: Free disk space on the server
Verify that the user account that is performing this procedure is a member of the Farm Administrators group.
On Server Manager, click Tools, and then click Disk Cleanup.
Resolution: Decrease the number of days to store log files
Verify that the user account that is performing this procedure is a member of the Farm Administrators group.
On the SharePoint Central Administration website, click Monitoring, in the Reporting section, click Configure diagnostic logging.
On the Diagnostic Logging page, in the Trace Log section, in the Number of days to store log files box, type a smaller number.
Click OK.