It would be great if this alert linked to at least the Disk Space Troubleshooting Guide http://docwiki.cisco.com/wiki/Cisco_Nexus_7000_Series_NX-OS_Troubleshooting_Guide_--_Troubleshooting_Memory (includes disk)
show system internal flash
show system internal /(full directory path)
In our case it is a logging problem where /var/log is the drive that is 100%. Investigating this further reveals that the libdt_helper.log in /var/log/external is very large. Searching on that reveals "Logging Problem Troubleshoot" which could indicate you are experiencing Cisco bug ID CSCue98451.