Today when I ssh into open scientific grid login node (login.osgconnect.net), it compliant about

Feb 17th, 2016: The home directory server is nearly full. Please clean out any
                unwanted files.

when I check my quota with df -h

nfs.ci-connect.net:/export/home/zcx
                      7.3T  7.1T  193G  98% /home/zcx

 When I use du -h on my home, it was found that I only use less than 10mb for /home/zcx and /home/zcx/stash combined. So how comes I have used up 7.1Tb of data?