A new Isilon administrator has created their first quota of 100 TB on a directory called "/ifs/Boston-zone/RnD". Both the Engineering and QA teams have access to this directory. The directory sits on a 4-node H400 node pool.
Two weeks later, the administrator notices that the team's available disk space is decreasing faster than anticipated for the "/ifs/Boston-zone/RnD" directory.
What is the most likely cause for the decrease in disk space?